AF-902 and AF-904

1000 Technology DrivePittsburgh, PA 15219-3120

COPYRIGHT © 2001UNION SWITCH & SIGNALPRINTED IN USA

AF-902 and AF-904Digital FSK Track Circuit

Controller Systems

FIELD MAINTENANCE MANUAL

July 2001Revision 2.0

SM8051

Union Switch & Signal, Inc.

i SM8051

REVISION HISTORY

REV DATE REVISION DESCRIPTION

0.0 10/9/98 Initial 902/904 manual

1.0 2/19/99 Revised per Shanghai and QA comments

1.1 4/20/99 Revised for submittal to Copenhagen

2.0 7/20/01 Revised for submittal to Copenhagen


iii SM8051

TABLE OF CONTENTS

1 GENERAL INFORMATION.............................................................................................. 1-1

1.1 INTRODUCTION ...........................................................................................................1-1

1.2 PHYSICAL DESCRIPTION...........................................................................................1-1

1.2.1 Cardfile.....................................................................................................................1-1

1.2.2 Printed Circuit Boards..............................................................................................1-3

1.2.3 Wayside Components...............................................................................................1-7

1.3 SPECIFICATIONS........................................................................................................1-10

2 Typical Applications ............................................................................................................ 2-1

2.1 Mainline Track Circuits ...................................................................................................2-2

2.1.1 Track Circuit ID and Cab Signal Transmission.......................................................2-2

2.2 Yard Track Circuits..........................................................................................................2-4

2.3 Cab-Only Transmission in Crossovers.............................................................................2-5

2.4 Train Detection Only in Double Crossover......................................................................2-6

2.5 SYSTEM CONNECTION DIAGRAMS.........................................................................2-6

3 FUNCTIONAL OPERATION ............................................................................................ 3-1

3.1 INTRODUCTION ...........................................................................................................3-1

3.2 WAYSIDE TO TRAIN MESSAGE FORMATION .......................................................3-1

3.2.1 Data Routing.............................................................................................................3-1

3.2.2 Data Protocol............................................................................................................3-2

3.2.3 Message Commands, Functions, and Formation.....................................................3-2

3.3 FSK SIGNAL TRANSMISSION....................................................................................3-3

3.3.1 Message Verification................................................................................................3-4

3.3.2 Equipment Room To Rails.......................................................................................3-5

3.4 TRAIN DETECTION......................................................................................................3-6


iv SM8051

3.4.1 Signal Level Sensing................................................................................................3-6

3.5 MONITORING AND FAILOVER..................................................................................3-6

3.5.1 MICROLOK II Monitoring......................................................................................3-7

3.5.2 AF-902/904 Monitoring...........................................................................................3-7

3.5.3 Failover (AF-902 System Only)...............................................................................3-9

4 FRONT PANEL MENU OPERATION .............................................................................. 4-1

4.1 INTRODUCTION ...........................................................................................................4-1

4.2 FRONT PANEL DISPLAYS AND CONTROLS...........................................................4-1

4.2.1 Displays ....................................................................................................................4-1

4.2.2 Controls ....................................................................................................................4-3

4.3 FRONT PANEL OPERATION.......................................................................................4-3

4.3.1 Front Panel Menu Interface......................................................................................4-4

4.4 MENU HIERARCHY......................................................................................................4-5

4.4.1 Main Menu...............................................................................................................4-5

4.4.2 Display Menu...........................................................................................................4-5

4.4.3 Blocking Speed Menu..............................................................................................4-6

4.4.4 Events Menu.............................................................................................................4-6

4.4.5 Configuration Menu.................................................................................................4-7

5 INSTALLATION AND ADJUSTMENT............................................................................ 5-1

5.1 INTRODUCTION ...........................................................................................................5-1

5.2 RECOMMENDED TEST EQUIPMENT........................................................................5-1

5.3 Serial Link Configuration.................................................................................................5-1

5.4 INITIAL POWER CHECKS ...........................................................................................5-1

5.5 TUNING PROCEDURE..................................................................................................5-2

5.6 CALIBRATION PROCEDURE......................................................................................5-2


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5.6.1 Testing Codes and Abbreviations ............................................................................5-3

5.6.2 Test Equipment And Tools ......................................................................................5-3

5.6.3 Transmit Power Adjustments...................................................................................5-4

5.6.4 Set-up Overview.......................................................................................................5-5

5.7 AF-902/904 TRACK CIRCUIT SYSTEM SET-UP AND TEST...................................5-6

5.7.1 AF-902/904 350 or 500 MCM Track Circuit Set-Up ..............................................5-7

5.8 TEST DOCUMENTATION AND DATA SHEETS.....................................................5-13

6 PREVENTIVE MAINTENANCE....................................................................................... 6-1

6.1 INTRODUCTION ...........................................................................................................6-1

6.2 IMPORTANCE OF PREVENTIVE MAINTENANCE..................................................6-1

6.3 PREVENTIVE MAINTENANCE TASKS.....................................................................6-1

6.3.1 Equipment Cleaning Procedure................................................................................6-1

6.3.2 Track Circuit Inspection...........................................................................................6-2

6.4 TRACK CIRCUIT CHECKS ..........................................................................................6-4

6.4.1 Track Circuit Sensitivity..........................................................................................6-4

7 TROUBLESHOOTING....................................................................................................... 7-1

7.1 INTRODUCTION ...........................................................................................................7-1

7.2 APPROACH TO TROUBLESHOOTING......................................................................7-1

7.3 TROUBLESHOOTING PROCEDURES........................................................................7-2

7.3.1 Fault Symptoms........................................................................................................7-2

7.3.2 Error Code Observation...........................................................................................7-3

7.4 PCB FRONT PANEL INDICATORS AND CONTROLS .............................................7-8

7.4.1 AF-902/904 CONTROLLER PCB..........................................................................7-8

7.4.2 AF-902/904 Auxiliary PCB ...................................................................................7-10

7.4.3 AF-902/904 Power Supply PCB............................................................................7-10


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8 CORRECTIVE MAINTENANCE...................................................................................... 8-1

8.1 INTRODUCTION ...........................................................................................................8-1

8.2 REPLACEMENT REPAIR..............................................................................................8-1

8.2.1 AF-902/904 PCB Replacement ................................................................................8-1

8.2.2 Coupling Unit Replacement.....................................................................................8-2

8.2.3 Bond Replacement ...................................................................................................8-5

8.3 VERIFICATION OF SYSTEM REPAIR........................................................................8-5

TABLE OF FIGURES

Figure 1-1 Typical Wayside Room Equipment...........................................................................1-2

Figure 1-2 AF-902/904 Cardfile Configuration..........................................................................1-3

Figure 1-3 Track Circuit Controller PCB.....................................................................................1-5

Figure 1-4 Auxiliary PCB............................................................................................................1-6

Figure 1-5 Power Supply PCB.....................................................................................................1-8

Figure 1-6 Track Coupling Unit, 350 or 500 MCM Bond, and Track Loop ...............................1-9

Figure 2-1 Application of Cab Signal Frequencies to Track Circuits..........................................2-3

Figure 2-2 Cab Signal Sequencing...............................................................................................2-3

Figure 2-3 Single Rail Track Circuit............................................................................................2-4

Figure 2-4 Typical Interlocking Cab-Only Transmission Loop..................................................2-5

Figure 2-5 Double Crossover (Train Detection Only) ................................................................2-6

Figure 2-6a Inductive Coupling Unit, Terminal Identification...................................................2-7

Figure 2-6b Direct Injection Coupling Unit, Terminal Identification.........................................2-7

Figure 2-7a AF-902 Track and AC Connectors and Typical Wiring...........................................2-8

Figure 2-7b AF-902 Typical Serial Link Connections ................................................................2-9

Figure 2-8 AF-904 Track and AC Connectors and Typical Wiring...........................................2-10


vii SM8051

Figure 4-1 Controller PCB Front Panel........................................................................................4-2

Figure 4-2 Menu System Hierarchy................................................................................. 4-9, 4-10

Figure 5-1 AF-902/904 Upper Cardfile Rear Views....................................................................5-4

Figure 7-1 Controller PCB Front Panel........................................................................................7-9

Figure 7-2 Auxiliary PCB Front Panel.......................................................................................7-11

Figure 7-3 Power Supply Front Panel........................................................................................7-12

Figure 8-1 Power Supply PCB.....................................................................................................8-3

TABLE OF TABLES

Table 5-1. Entering The AF902/904 Restricted Menu For Set-Up.............................................5-6

Table 5-2. AF-902/904 MLOK Address and Track Circuit ID Settings.....................................5-6

Table 5-3. Af-902/904 350 or 500 MCM Tuning Instructions ...................................................5-7

Table 5-3A Coupling Unit (Nominal Capacitance Setting).........................................................5-8

Table 5-4. AF-902/904 350 or 500 MCM Calibration Procedure...............................................5-8

Table 5-4B Rail Current Settings (350 MCM, 500 MCM, and Cab Loop Circuits) .................5-10

Table 5-4C Rail Current Settings (Direct Inject Circuits)..........................................................5-10

Table 5-5. AF-902/904 Cab Loop Track Circuit Set-Up ...........................................................5-11

Table 5-6. AF-902/904 Direct Inject Track Circuit Set-Up .......................................................5-12

LIST OF ABBREVIATIONS

AAR Association of American Railroading

ac Alternating Current

ATC Automatic Train Control

ATP Automatic Train Protection

BFSK Binary Frequency Shift Keyed


viii SM8051

BPF Band Pass Filter

CMOS Complementary Metal Oxide Semiconductor

CPS Conditional Power Supply

CRC Cyclic Redundancy Check

CTC Centralized Traffic Control

CU Coupling Unit

DC Direct Current

EEPROM Electrically Erasable Programmable Read Only Memory

ESS Emergency Stop System

FET Field Effect Transistor

FSK Frequency Shift Keyed

IC Integrated Circuit

IF Intermediate Frequency

LCP Local Control Panel

LED Light Emitting Diode

LO Local Oscillator

LPF Low Pass Filter

LRU Lowest Repairable Unit

MCM thousands (M) of Circular Mils

MCP Master Control Panel

MCU Micro Controller Unit

MLOK MICROLOK II

MPU Micro Processor Unit

NCO Numerically Controlled Oscillator

NRZI Non-return-to-zero inverted


ix SM8051

NVLE Non-vital Logic Emulator

PC Personal Computer

PCB Printed Circuit Board

PMI Preventive Maintenance Inspection

PVC Poly Vinyl Chloride

PWM Pulse Width Modulator

RAM Random Access Memory

RF Radio Frequency

rms root mean square

SDLC Synchronous Data Link Control

SER Signal Equipment Room

SIM System Integration Module

SPDT Single Pole Double Throw

TCCB Train Control and Communications Building

TWC Train to Wayside Communications

V Volts

VHM Vehicle Health Monitor


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1-1 SM8051

1 GENERAL INFORMATION

1.1 INTRODUCTION

This service manual is intended for use with both the AF-902 and AF-904 digital FrequencyShift Keyed (FSK) track circuit controller systems. The AF-902 system includes redundantequipment for failover operation, while the AF-904 system does not. When describing featurescommon to both systems, the term "AF-902/904" is used.

The AF-902/904 system is part of the wayside portion of an Automatic Train Control (ATC)system. It is the primary communications interface between the wayside and the carborneequipment. The AF-902/904 system provides both train detection and transmission of digital cabsignaling data for the Automatic Train Protection (ATP) function of an ATC system. Figure 1-1,Typical Wayside Room Equipment shows the equipment that is contained in a typical waysideroom.

To perform its primary functions of train detection and cab signaling, the AF-902/904 systemencodes data from the track logic processor on the wayside and puts it on the track where it ispicked up and decoded by the carborne ATP equipment. This data is used for line speed, targetspeed, track length, grade, direction, door control, next frequency, and coupling/uncouplinginformation. Vital track logic is performed by the Track MICROLOK II system. Interlockinglogic and control of switch machines and signals are performed by the Interlocking MICROLOKII. Non-vital logic is performed by Non-Vital Logic Emulator (NVLE) units. Routing isperformed automatically by the train ID (through the wayside communications system), from thelocal control panel, by fleeting, or from central control.

The AF-902/904 system is comprised of the trackside equipment and processing equipmentwithin the signal equipment room. The trackside equipment consists of track coupling units, wirebonds, and track loops.

As shown in Figure 1-1, Typical Wayside Room Equipment, the processing equipment for anAF-902 system contains the primary and backup circuits. The MICROLOK II units and NVLEunits are also duplicated for failover conditions.

Transit Lines requiring multiple track circuits can be equipped with a maximum of 12 AF-902/904 track circuits per track MICROLOK II system.

1.2 PHYSICAL DESCRIPTION

1.2.1 Cardfile

The AF-902/904 cardfile is comprised of electronic PCBs housed in a chassis that is compatiblewith a 19" wide AF rack. This equipment is located in the equipment room and requires a powerinput of 110/240V ac@50/60 Hz (nominal).

This rack mount unit shares many design features with US&S's highly successful MICROTRAXCoded Track Circuit and MICROCAB Cab Signal Systems, including integral PCB front edge


1-2 SM8051

U

AF902

Figure 1-1 Typical Wayside Room Equipment

control/display panels, menu-driven alphanumeric Light Emitting Diode (LED) displays, and 9-pin serial data ports.

Figure 1-2, AF-902/904 Cardfile Configuration, shows the layout of the AF-902/904 cardfiles.Each cardfile contains ten PCBs, all of which plug into a motherboard that is mounted to theback of the cardfile. The motherboard is a printed circuit board that provides connectionsbetween the PCBs. Connectors for each PCB are mounted on the motherboard. When the PCBsare installed in the cardfile, the edge connectors on the PCBs slide into the connectors on themotherboard. In the AF-902 system, the cardfile contains two track circuits. Each track circuitcontains five PCBs. These five PCBs are configured to provide redundant primary and backupunits. The primary unit consists of:

• One track circuit controller PCB

• One auxiliary PCB

• Half of a power supply PCB

Likewise, the backup track circuit unit consists of:





1-3 SM8051

One power supply PCB, with two independent supply systems, is common to the primary andbackup sections of one track circuit.

The AF-904 cardfile has the same exact PCB layout, but does not provide redundant track circuitunits. Instead the ten PCBs are configured as four separate track circuits. Each track circuitconsists of:




One power supply PCB, with two independent supply systems, is common to two separate trackcircuits.

1.2.2 Printed Circuit Boards

The AF-902/904 cardfile PCBs are modular in design which allows for easy removal andreplacement should repair become necessary. Since the stored programming is located on

TRACK CIRCUIT #1 TRACK CIRCUIT #2 TRACK CIRCUIT #3 TRACK CIRCUIT #4

TRACK CIRCUIT #2TRACK CIRCUIT #1AF-902:

AF-904:

POWER SUPPLYN12 36 05 01

ONOFF

+15V

-15V

+5V

+15V

-15V LEF

TPO

WER

SU

PPLY

GND

OFF

RIG

HT

PO

WE

R S

UPP

LY

LEF

TPO

WER

SU

PPLY

POWER SUPPL YN12 36 05 01

0

ON

0

XMFR

+5V

+15V

-15V

X MFR

X MFR

+5V

ON

+15V

-15V

+5V

ON

+15V

OFF

-15V

0

GND

0

OFF

GND

-15V

+15V

+5V

-15V

+15V

+5V

+5V

XMFR

-15V

RIG

HT

PO

WE

R S

UPP

LY+15V

+5V

GND

AUXIL IARYBOARD

N1236 040 1

CPS ACTIVE

ON -LIN E

SELF

PARTN ERHEALTH

U -LOK C OMM

BL OCK SPEED SET

LEVEL

DATA

TRACKCLEAR

P1

P2RECEI VER

INPU T

+12V

+5V

VITALOUTPUTS

BA ND PASS FI LTER

ANALOG GROUND

+44V

SYST EM GROUND

+

-

CPS 500Hz

TRANSMIT TEROUTPUT

AUXIL IARYBOARD

N123 6040 1

CPS ACTIVE

ON-LI NE

SELF

PARTN ERHEALTH

U -LOK COMM

B LOCK SPEED SET

LEVEL

D ATA

TRACKCLEAR

P1

P2RECEIVER

IN PUT

+12V

+5V

VITALOUTPUTS

B AND PASS FI LTER

ANALOG GROUND

+44V

SYST EM GROUND

+

-

CPS 500Hz

T RANSMIT TEROUTPUT

AUXIL IARYBOARD

N1236 040 1

C PS ACTIVE

ON-LI NE

SELF

PAR TN ERH EALTH

U -LOK COMM

B LOC K SPEE D SET

LEVEL

D ATA

TRACKCLEAR

P1

P2RECEIVER

IN PUT

+12V

+5V

VITALOUTPU TS

B AND PASS FI LTER

ANALOG GROUND

+44V

SYST EM GROUND

+

-

C PS 500H z

T RANSMIT TEROUTPUT

AUXILIARYBOARD

N123 60 401

C PS ACTIV E

ON-LI NE

SELF

PAR TNERH EALTH

U -LOK COMM

B LOC K SPEE D SE T

LEVEL

D ATA

TRACKCLEAR

P1

P2RECEIVER

I NPUT

+12V

+5V

VI TALOUTPU TS

B AND PASS FILTER

ANALOG GROUND

+44V

SYSTEM GROUND

+

-

C PS 500Hz

T RANSMI TTEROUTPUT

UP

D OWN

ADJMODE

AUX 1

PRESS T ORESET

IN RESETWHEN LIT

ESCAPE

STAT USLEDS 2

1

DIR.

W

E

DEBUGPORT

TRK CKTCTRLR

N1236 03- 0 1

DIAGPORT

UP

DOWN

ADJMODE

AU X 1

PRESS T ORESET

IN RESETWHEN LIT

ESC APE

STAT USLEDS 2

1

DIR.

W

E

DEBUGPORT

TRK CKTCTRLR

N1236 03- 0 1

DIAGPORT

UP

DOWN

ADJMODE

AU X 1

PRESS TORESET

IN RESETWHEN LIT

ESCAPE

STATUSLEDS 2

1

DIR.

W

E

DEBUGPORT

TRK CKTCTRLR

N1236 0 3-0 1

DIAGPORT

UP

DOWN

ADJMODE

AU X 1

PRESS TORESET

IN RESETWHEN LIT

ESCAPE

STATUSLEDS 2

1

DIR.

W

E

DEBUGPORT

TRK CKTCTRL R

N123 60 3- 01

DIAGPORT

ENTER AUX 2 ENTER AUX 2 ENTER AUX 2 ENTER AUX 2

Figure 1-2 AF-902/904 Cardfile Configuration


1-4 SM8051

EEPROMs that are mounted on the cardfile backplane, replacement of any logic PCB may bedone with little reprogramming. A calibration procedure should be performed to verify propertrack circuit operation. Adjustments are also made via jumpers on the cardfile backplane so that asystem reset is not required with changeout of the track interface circuitry.

All power is supplied to the PCBs via the backplane motherboard. The ll0/240V ac@50/60 Hz isconnected to the power supply PCB, which in turn supplies the controller and auxiliary circuitrywith the required voltages. Since this system operates directly from the ac mains, caution shouldbe taken when working near the backplane or on the power supply, especially when on anextender board.

Both primary units within the AF-902 cardfile are powered from the same ac feed. Likewise,both backup units are powered from the same second ac feed.1.2.2.1 Track Circuit Controller PCB

Figure 1-3, Track Circuit Controller PCB, shows the front panel of the track circuit controllerPCB and the location of these PCBs in the cardfile. The heart of the track circuit controller is aMotorola MC68HC16Z1 Complementary Metal Oxide Semiconductor (CMOS) Microcontroller.Many of the support functions necessary for the make-up of a microprocessor-based device areinternally incorporated in the 68HC16's System Integration Module (SIM). In addition to theSIM, the 68HC16 contains several on-chip peripherals that reduce the PCB's chip count. Thiscontributes greatly to the compactness of the AF-902/904 unit.

The end user is provided with:

• Two alphanumeric displays. These are used to monitor the data used in set-up andoperation of the track circuit. The upper display is red and the lower display is green..

• Four momentary contact Single Pole Double Throw (SPDT) toggle switches. Theseswitches are used for inputting data that is required for set-up conditions.

• Five LEDs. These supply additional information, as described in Section 5.2.1.

• A PC-compatible serial port. A female DB9 connector provides an RS-232 DTE portused for detailed monitoring and diagnostics of the AF-902/904 logic and memory.

• Background Debugging Port. This port is used for direct control of the 68HC16microprocessor. It is primarily for factory use.

1.2.2.2 Auxiliary PCB

Figure 1-4, Auxiliary PCB, shows the front panel of the auxiliary PCB and the location of thesePCBs in the cardfile. The auxiliary PCB contains both the power amplifier for track datatransmissions and the front end part of the receiver for incoming track signals, as well as theConditional Power Supply (CPS) subsystem. Relays used for failover to the alternate subsystemare located on this PCB, making it an ideal system monitoring point.


1-5 SM8051

UP

DOWN

ADJMODE

AUX 1

PRESS TORESET

IN RESETWHEN LIT

ESCAPE

STATUSLEDS 2

1

DIR.

W

E

DEBUGPORT

TRK CKTCTRLR

N123603- 01

DIAGPORT

ALPHANUMERICLED DISPLAYS

MOTOROLABACKGROUNDDEBUG PORT

(FACTORY USE ONLY)

CONFIGURATION SETUPSWITCHES

MOMENTARY CONTACTSWITCHES

(SPRING RETURN TO CENTER)

SYSTEM MONITORLEDS

SYSTEM RESETPUSHBUTTON

9-PIN PORTFOR

PORTABLE PC(RE-232DTE)

AF-902 / AF-904 CONTROLLERPCB

ENTER AUX 2

Figure 1-3 Track Circuit Controller PCB


1-6 SM8051

The following are located on the auxiliary PCB front panel:

• Eight LEDs. These indicate the status of various key parameters in a readilyinterpreted format.

• Eleven maintenance test points. These provide accessible test points for voltage andsignals covering the controller and auxiliary PCBs.

AUXILIARYBOARD

N12360401

CPS ACTIVE

ON- LINE

SELF

PARTNERHEALTH

U- LOK COMM

BLOCK SPEED SET

LEVEL

DATA

TRACKCLEAR

P1

P2RECEIVER

INPUT

+12V

+5VVITAL

OUTPUTS

BANDPASS FILTER

ANALOG GROUND

+44V

SYSTEM GROUND

+

-

CPS 500Hz

TRANSMITTEROUTPUT

SYSTEM MONITORLEDS

MAINTENANCETEST POINTS

AF-902 / AF-904 AUXILIARYPCB

Figure 1-4 Auxiliary PCB


1-7 SM8051

1.2.2.3 Power Supply PCB

Figure 1-5, Power Supply PCB, shows the front panel of the power supply PCB and the locationof these PCBs in the cardfile. The single power supply PCB in each AF-902/904 subsystemprovides both subsystems with regulated operating power for internal components. This PCBinterfaces standard ac commercial power to the system. For safety purposes, a solderside cover isprovided to reduce the risk of electrical shock when removing the PCB from the cardfile.

WARNING

Dangerous voltages are exposed when operating the powersupply PCB on an extender board. Use extreme caution whenworking near exposed terminals. Failure to do so could result inserious physical injury or loss of life.

The front panel has the following features:

• Fourteen LEDs. There are seven LEDs for the primary power monitoring and sevenfor the backup power monitoring.

• Two separate power switches. The upper power switch energizes the two PCBs to theimmediate right of each power supply PCB. The lower power switch energizes thetwo PCBs to the immediate left of each power supply PCB. (Note: These switches arelocking-lever type switches that must be pulled out to toggle.)

• Four Key Voltage Test Points. There are test points for both subsystem supplies.

Note that each subsystem is driven from a separate ac feed for improved system reliability.

1.2.3 Wayside Components

The required supporting trackside components for the AF-902/904 are the track coupling units,wire bonds, and track loops.

From the equipment room, track leads of up to several kilometers total loop length connect thetrackside coupling units to the direction relays. The track leads are twisted pairs with an intrinsicimpedance (Zo) of approximately 100 ohms.

1.2.3.1 Coupling Units

Figure 1-6, Track Coupling Unit, 350 or 500 MCM Bond, and Track Loop, shows a trackcoupling unit. The AF-902/904 track coupling unit interfaces the track signals with the cardfilereceiver and transmitter circuits, and provides for tuning to the track circuit carrier frequency.The coupling units are housed in weather tight enclosures, and consist of two totally independentand isolated coupling circuits. Each circuit has its own transformer and a jumper-adjustedcapacitor bank for frequency tuning as required for the track loops.


1-8 SM8051

POWER SUPPLYN12360501

ONOFF

+15V

- 15V

+5V

+15V

- 15V LE

FTP

OW

ER

SU

PP

LY

GND

OFF

0

ON

0

XMFR

+5V

+15V

- 15V

+5V

XMFR

- 15V

RIG

HT

PO

WE

R S

UP

PL

Y+15V

+5V

GND

LOCKINGSUBSYSTEM

POWER SWITCH

AC POWERTEST POINTS

POWERMONITOR

LEDS

DC POWERTEST POINTS

LOCKINGSUBSYSTEM

POWER SWITCH

POWERMONITOR

LEDS

DC POWERTEST POINTS

AF-902 / AF-904 POWER SUPPLYPCB

Figure 1-5 Power Supply PCB


1-9 SM8051

23 FT. (7 m)

350 (177 mm ) OR 500 (253 mm ) MCM CABLE

AF-902/904350 OR 500 MCM

BOND

TM

TM

1-TURNLOOP

1-TURN LOOP (#12) (4 mm )

AF-902/904TRACK

COUPLINGUNIT

TOEQUIPMENT

HOUSE 2 TWISTEDPAIRS (#14) (2.08 mm )

MAX. CABLELENGTH = 6000 FT. (1,830 m)

COUPLING UNIT

2 2

2

2

COLLAR FOR CABLES

LOOP CABLE

BOND CABLE

BOND AND LOOP CABLE MOUNTING

Figure 1-6 Track Coupling Unit, 350 or 500 MCM Bond, and Track Loop

Track Coupling Unit:

Dimensions: 16"W x 8"H x 10"L (40.64 cm x 20.32 cm x 25.4 cm)Mounting: Wayside Ground Base or Wall.

Coupling Unit Feed:

6000 ft. (1,830 m) (maximum) twisted pair #14

1.2.3.2 350 or 500 MCM BONDS

Signals and messages in the rails are communicated to and from the AF-902/904 cardfiles viasimple but highly effective cabling type bonds known as "350MCM" or "500MCM" bonds.Insulated joint rails are not required. AF-902/904 track coupling units are tuned to the carrierfrequency and provide impedance matching to/from the track.

The 350 or 500 thousands (M) of Circular Mils (MCM) bond consists of a few meters of 350 or500 MCM cable that is connected between the two rails in an "S" shape or an “O” shape with theend of the "S" or “O” bonded to each rail. Single turn track loops are mounted inside the upperand lower parts of the "S" or in the “O” part. “S” bonds are used in areas where there are noinsulated joints that define the track circuit boundaries. “O” bonds are used in areas where aninsulated joint is used in each rail to define the track circuit boundaries. Which track does thetransmitting or receiving is determined by the direction relays located at the rear of the cardfile.


1-10 SM8051

1.3 SPECIFICATIONS

A. Track Carrier Frequencies

Odd Frequencies Even Frequencies

F0 9.5 kHz F1 10.5 kHz

F2 11.5 kHz F3 12.5 kHz

F4 13.5 kHz F5 14.5 kHz

F6 15.5 kHz F7 16.5 kHz

Frequency Shift: + 200 Hz

Modulation: BFSK carrier

Baud Rate: 200 BPS

B. Cab Signal Data Transmission

Signal Message: 37 data bits, 8 header bits, 16 Cyclic Redundancy Check(CRC) validation bits.

Protocol: Synchronous, bit oriented (similar to Synchronous DataLink Control (SDLC))

Encoding: NRZI

Bits Name Function

12 Track Circuit ID Identification of present track circuit (0 to 4095)

1 Primary/Backup Identification of which controller is providing themessage

2 Direction Train direction of travel

3 Next Frequency Carrier frequency of the next track circuit

7 Distance to Go Distance of target speed

4 Line Speed Maximum speed permitted within track circuit

4 Target Speed Desired speed at track circuit target

1 Berthed (Door) OK to open vehicle doors at station


1-11 SM8051

2 Couple/Uncouple Couple/Uncouple of trains for makeup

1 Bifurcation Bifurcation

Security: Two messages, CRC continuous reception.

Speed Commands: 0 mph to 80 kph

C. Track MICROLOK II Data Transmission

Signal Message: 24 data bits, 8 header bits, 8 address bits, 24 CyclicRedundancy Check (CRC) validation bits.

Protocol: US&S vital serial link protocol

Data from Track MICROLOK II to AF-902/AF-904:

Bits Name Function Description

2 Direction Traffic/Direction 10 = East01 = West

3 Next Frequency Next Frequency See next frequencychart below

6 Distance to Go Target Distance to Go See distance chartbelow

4 Line Speed Line Speed See speed chart below

4 Target Speed Target Speed See speed chart below

1 Berthed Berthed 1 = train not inplatform0 = train in platform

2 Couple/Uncouple Couple/Uncouple 10 = couple to train01 = uncouple fromtrain00 = no action

1 Bifurcation Bifurcation 1 = point N0 = point R

1 Target Distance Target Distance See distance chartbelow


1-12 SM8051

Next Frequency Chart

Frequency(kHz)

BinaryValue

9.5 0 0 0

10.5 0 0 1

11.5 0 1 0

12.5 0 1 1

13.5 1 0 0

14.5 1 0 1

15.5 1 1 0

16.5 1 1 1

Speed Chart

Speed(kph)

BinaryValue

0 0 0 0 0

3 0 0 0 1

5 0 0 1 0

10 0 0 1 1

15 0 1 0 0

30 0 1 0 1

35 0 1 1 0

40 0 1 1 1

45 1 0 0 0

50 1 0 0 1

55 1 0 1 0

60 1 0 1 1

65 1 1 0 0

70 1 1 0 1

75 1 1 1 0

80 1 1 1 1


1-13 SM8051

Distance Chart

Distance(meters)

BinaryValue

0 0 0 0 0 0 0 0

6 0 0 0 0 0 0 1

12 0 0 0 0 0 1 0

18 0 0 0 0 0 1 1

24 0 0 0 0 1 0 0

30 0 0 0 0 1 0 1

36 0 0 0 0 1 1 0

42 0 0 0 0 1 1 1

48 0 0 0 1 0 0 0

54 0 0 0 1 0 0 1

60 0 0 0 1 0 1 0

66 0 0 0 1 0 1 1

72 0 0 0 1 1 0 0

78 0 0 0 1 1 0 1

84 0 0 0 1 1 1 0

90 0 0 0 1 1 1 1

96 0 0 1 0 0 0 0

102 0 0 1 0 0 0 1

108 0 0 1 0 0 1 0

114 0 0 1 0 0 1 1

120 0 0 1 0 1 0 0

126 0 0 1 0 1 0 1

132 0 0 1 0 1 1 0

138 0 0 1 0 1 1 1

144 0 0 1 1 0 0 0

150 0 0 1 1 0 0 1

156 0 0 1 1 0 1 0

162 0 0 1 1 0 1 1

168 0 0 1 1 1 0 0

174 0 0 1 1 1 0 1

180 0 0 1 1 1 1 0

186 0 0 1 1 1 1 1

Distance(meters)

BinaryValue

192 0 1 0 0 0 0 0

198 0 1 0 0 0 0 1

204 0 1 0 0 0 1 0

210 0 1 0 0 0 1 1

216 0 1 0 0 1 0 0

222 0 1 0 0 1 0 1

228 0 1 0 0 1 1 0

234 0 1 0 0 1 1 1

240 0 1 0 1 0 0 0

246 0 1 0 1 0 0 1

252 0 1 0 1 0 1 0

258 0 1 0 1 0 1 1

264 0 1 0 1 1 0 0

272 0 1 0 1 1 0 1

278 0 1 0 1 1 1 0

284 0 1 0 1 1 1 1

290 0 1 1 0 0 0 0

296 0 1 1 0 0 0 1

302 0 1 1 0 0 1 0

308 0 1 1 0 0 1 1

314 0 1 1 0 1 0 0

320 0 1 1 0 1 0 1

326 0 1 1 0 1 1 0

332 0 1 1 0 1 1 1

338 0 1 1 1 0 0 0

344 0 1 1 1 0 0 1

350 0 1 1 1 0 1 0

356 0 1 1 1 0 1 1

362 0 1 1 1 1 0 0

368 0 1 1 1 1 0 1

372 0 1 1 1 1 1 0

378 0 1 1 1 1 1 1


1-14 SM8051

Distance(meters)

BinaryValue

384 1 0 0 0 0 0 0

390 1 0 0 0 0 0 1

396 1 0 0 0 0 1 0

402 1 0 0 0 0 1 1

408 1 0 0 0 1 0 0

414 1 0 0 0 1 0 1

420 1 0 0 0 1 1 0

426 1 0 0 0 1 1 1

432 1 0 0 1 0 0 0

438 1 0 0 1 0 0 1

444 1 0 0 1 0 1 0

450 1 0 0 1 0 1 1

456 1 0 0 1 1 0 0

462 1 0 0 1 1 0 1

468 1 0 0 1 1 1 0

472 1 0 0 1 1 1 1

474 1 0 1 0 0 0 0

478 1 0 1 0 0 0 1

480 1 0 1 0 0 1 0

484 1 0 1 0 0 1 1

486 1 0 1 0 1 0 0

490 1 0 1 0 1 0 1

496 1 0 1 0 1 1 0

500 1 0 1 0 1 1 1

506 1 0 1 1 0 0 0

512 1 0 1 1 0 0 1

518 1 0 1 1 0 1 0

524 1 0 1 1 0 1 1

530 1 0 1 1 1 0 0

536 1 0 1 1 1 0 1

540 1 0 1 1 1 1 0

546 1 0 1 1 1 1 1

552 1 1 0 0 0 0 0

Distance(meters)

BinaryValue

558 1 1 0 0 0 0 1

564 1 1 0 0 0 1 0

570 1 1 0 0 0 1 1

600 1 1 0 0 1 0 0

630 1 1 0 0 1 0 1

660 1 1 0 0 1 1 0

690 1 1 0 0 1 1 1

720 1 1 0 1 0 0 0

750 1 1 0 1 0 0 1

780 1 1 0 1 0 1 0

810 1 1 0 1 0 1 1

840 1 1 0 1 1 0 0

870 1 1 0 1 1 0 1

900 1 1 0 1 1 1 0

930 1 1 0 1 1 1 1

960 1 1 1 0 0 0 0

990 1 1 1 0 0 0 1

1020 1 1 1 0 0 1 0

1050 1 1 1 0 0 1 1

1080 1 1 1 0 1 0 0

1110 1 1 1 0 1 0 1

1140 1 1 1 0 1 1 0

1170 1 1 1 0 1 1 1

1200 1 1 1 1 0 0 0

1350 1 1 1 1 0 0 1

1500 1 1 1 1 0 1 0

1650 1 1 1 1 0 1 1

1800 1 1 1 1 1 0 0

1950 1 1 1 1 1 0 1

2400 1 1 1 1 1 1 0

2900 1 1 1 1 1 1 1


1-15 SM8051

D. Data from AF-902/AF-904 to MICROLOK:

Bits Name Function Description

1 Direction Block Speed 0 = no block speed set1 = block speed set

1 Standby Health Standby Health 0 = standby unit not available1 = standby unit is available

1 Occupancy Track Occupancy 0 = track occupied1 = track unoccupied

1 Correspondence Correspondence 0 = direction not incorrespondence1 = direction is incorrespondence

4 Spare Spare Spare bits that are notused

Security: Two messages per CRC

Speed Commands: 0 – 80 Kph

E. Track Circuit

Track Circuit Length: 1000 ft. (305 m) maximum; 65 ft. (19.812 m) minimum

Shunt Sensitivity: < 0.25 ohms

Pre/Post Shunting: < 5.0 ft (1.524 m)

F. Control Cardfile

Power Input: 110/240V ac@50/60 Hz (50 watts per track circuit)

Input Power Protection: 10 Amp fuse

Environmental: -25°C to 70°C with 95% humidity (non-condensing)

Circuits: Primary and backup track circuit in each

G. Coupling Unit

Coupling Feed: 6000 ft. (1,828.8 m) maximum, with twisted pair of #14AWG

Tuned Circuit: Connected to 1-turn loopH. 350 or 500 MCM Bond:

Cable Bond: 350 or 500 MCM conductiveSignal exchange: Inductive Coupling1V+: Break rail film for shunting (direct connection to coupling

unit only)Impedance: 1.0 ohm (approximately)

Cab signal current: 100 ma @ 9.5 kHz


1-16 SM8051



2-1 SM8051

2 Typical Applications

This section provides an overview of the AF-902/904 system and its functional responsibilitieswithin the wayside application.

The AF-902/904 system has been designed as a communication interface between theinterlocking logic, processed by MICROLOK II units, and the equipment on the vehicle used forcontrolling the movement and speed of a train. The AF-902/904 equipment takes serial inputfrom MICROLOK II, adds any local information, and transmits this combined data to the trainthrough the rails. The interface to MICROLOK II is a bi-directional serial link as described inthe MICROLOK II service manuals. The communication interface to the train is a one-way linkwhere the car receives only.

The AF-902/904 transmits, into one end of the track circuit, information such as track circuit ID,target speed, line speed, distance-to-go, berthed, direction, next cab carrier frequency,coupling/uncoupling and bifurcation. It also monitors the other end of the track circuit to detecttrain occupancy. Vital wayside logic is typically performed by the US&S MICROLOK IIsystem. A typical wayside system is illustrated in Figure 1-1, Typical Wayside Room Equipment.

A. AF-902/904 circuits are used for both train detection and cab signaling. Crossovers andturnouts use the PF track circuits for train detection and AF-902/904 cab loops for datacommunications to the carborne ATC system. PF track circuits are described in US&SService Manual 6087.

B. The AF902/904 signals are coupled into the track via S bonds, O bonds or direct injection asdescribed in sections 1.2.3.2.

C. When the AF902/904 receiver senses a low amplitude or incorrect data, as compared to thepredetermined threshold level and track ID, it indicates that the track circuit is shunted by anoccupying vehicle.

D. The track circuit continuously transmits digitally formatted data to the vehicle using BFSKmodulation.

E. As the vehicle travels from track circuit to track circuit, the carborne ATC system tunes afilter on the vehicle to the correct frequency, allowing the vehicle to receive the data for thecorrect track frequency only.

F. Upon notification of the next track circuit carrier frequency, a filter is electronically selectedto receive and decode the vital information on one of the eight carrier frequencies that isassigned to the upcoming track circuit.

G. The vehicle's ATP subsystem uses the FSK-formatted vital information decoded data toperform the ATP functions.


2-2 SM8051

2.1 MAINLINE TRACK CIRCUITS

The AF-902/904 system is configured for simple, highly-reliable track interface applicationsusing jointless track circuits.

The carrier signals and modulated data signals are coupled to the rails via the 350 or 500 MCMbond and coupling unit located at each end of the track circuit. The amplitude of the carrier andthe track ID data signals are used to determine track occupancy. The modulated FSK data signalis used to transmit vital and non-vital data to the vehicle.

2.1.1 Track Circuit ID and Cab Signal Transmission

As the train travels from track circuit to track circuit within the mainline territory (station-to-station), track occupancy and isolation of commands between track circuits is accomplished byalternating eight available data carrier frequencies. Frequencies range from 9.5 to 16.5 kHz in 1kHz steps and are numbered F0 through F7. Three frequencies (F1, F3, and F5) are assigned towestbound or northbound track circuits, and three frequencies (F2, F4, and F6) go eastbound orsouthbound. The two remaining frequencies (F0 and F7) are usually used in special work areas.

Specifically, the layout of the mainline track circuits should follow the two three-frequencyrotations shown in Figure 2-1, Application of Cab Signal Frequencies to Track Circuits. If it isnot possible to separate two track circuits of the same carrier frequency by two intervening trackcircuits, then separation by one intervening track circuit plus a set of insulated joints isacceptable.

Since the train must be informed of the next track circuit frequency, and its occupancy, the trackMICROLOK II will not transmit the frequency of an occupied track circuit to the following train.Instead, the frequency of the track circuit the following train is currently occupying is repeated.This initiates a High Rate Service Braking action. The train remains stopped until either theoperator initiates a Search for Next Frequency Command from the vehicle's Master ControlPanel (MCP) or until the same command is received via a Radio Release Message.

As shown in Figure 2-1, Application of Cab Signal Frequencies to Track Circuits, carrierfrequency F1 contains data that informs the train of the next cab signal frequency (F3). Onboardthe train, one receiver is tuned to F1 and the other to F3. As the train approaches the 350 or 500MCM bond, signal F1 drops out. Once valid data and level is detected on F3, the vehicle ignoresthe data arriving from the old F1 receiver. The new data is then decoded and the vehicle logicretunes the receiving filter (previously tuned to F1) to the next cab signal frequency in thesequence of track circuit frequencies (see Figure 2-2, Cab Signal Sequencing).

The track circuit is arranged so that the train is always heading towards the transmitter. This iscontrolled by the two assigned Direction Control bits within the message format.

Each wayside track circuit continuously transmits digitally-formatted data to the vehicle usingFSK modulation. The track MICROLOK II determines most of the information in the 37 databits and passes this data on to each AF-902/904 track circuit, via vital serial communicationlinks, where the data is encoded.


2-3 SM8051

The first 8 bits are used for synchronizing the onboard decode function. The next 36 bits containdata. The last 16 bits of the message are the CRC bits for error detection. Message configurationand bit assignments are described in Section 3.

Once the system knows the track ID and the train's direction of travel, it can initiate speedrestrictions. Two types of speed restrictions are initiated by the ATC system: block speedrestrictions and zone speed restrictions. Block speed restrictions are selected by the Maintainerfor each AF-902/904 track circuit. Zone speed restrictions limit the target speed for a controlline. The AF-902/904 is designed to enable selection of the maximum line speed and target speedpermitted to be transmitted by a track circuit.

REC. 1: F1REC. 2: F3

REC. 1: F3REC. 2: F5

T.C. “2103”F1 = 10.5 kHz

T.C. “2103”F1 = 10.5 kHz

T.C. “2102”F3 = 12.5 kHz

T.C. “2102”F3 = 12.5 kHz

T.C. “2101”F5 = 14.5 kHz

T.C. “2101”F5 = 14.5 kHz

T.C. “2100”F1 = 10.5 kHz

T.C. “2100”F1 = 10.5 kHz

T.C. “2099”F3 = 12.5 kHz

T.C. “2099”F3 = 12.5 kHz

TRAFFICDIRECTION

TRAFFICDIRECTION

TRAIN IN TRACKCIRCUIT “2103”

TRAIN IN TRACKCIRCUIT “2102”

RECEIVER #1 TUNED TO F1RECEIVER #2 TUNED TO F3APPROACH T.C. “2102” F1 OUTF3 RECEIVED

RECEIVER #1 TUNED TO F3RECEIVER #2 TUNED TO F5APPROACH T.C. “2101” F1 OUTF5 RECEIVED

T.C. “99”F4 = 13.5 kHz

T.C. “99”F4 = 13.5 kHz

T.C. “100”F6 = 15.5 kHz

T.C. “100”F6 = 15.5 kHz

T.C. “101”F2 = 11.5 kHz

T.C. “101”F2 = 11.5 kHz

T.C. “102”F4 = 13.5 kHz

T.C. “102”F4 = 13.5 kHz

T.C. “103”F6 = 15.5 kHz

T.C. “103”F6 = 15.5 kHz

Figure 2-1 Application of Cab Signal Frequencies to Track Circuits

F RECEIVED

F RECEIVED

F

TF

350 OR 500 MCM BOND

1

3

3

1

Figure 2-2 Cab Signal Sequencing


2-4 SM8051

The Distance-to-Go bits represent the distance to the target speed, which is the desired speed ofthe train at the end of the control line.

Train Detection and signal communications are similar to those of the mainline continuous railterritory with the exception of the Berthed recognition bits contained in the message.

Wayside and carborne signals are used to determine if the train is totally within the limits of theplatform. A relay, called Berthed, is used to indicate to the wayside to turn on the Berthed bit.The train must be positioned in the platform track circuit for five seconds before this command istransmitted to the train via the AF-902/904 track circuit. When the command is transmitted, thisenables the train doors to open. This is described in more detail in Section 3.

2.2 YARD TRACK CIRCUITS

In addition to their use for station-to-station operations, the AF-902/904 track circuits areemployed in the storage yard. Here, the system allows automatic movement of cars for thepurpose of making up new train configurations. The AF-902/904 is ideally suited for short trackcircuits and slow train movement in the yard.

Yard track circuits use the same carrier frequency assignments and rotations as the mainlinetrack circuits - F1, F3, and F5 for west/north circuits and F2, F4, and F6 for east/south circuits.However, for yard track circuits, it is only necessary to separate two track circuits of the samecarrier frequency by one intervening track circuit. Figure 2-3, Single Rail Track Circuit, showsthis configuration.

The cab signal is injected into the rails via direct-inject connection of the coupling unit to therails (see Figure 2-6b). The direct injection method is used because only one rail of the track

Figure 2-3 Single Rail Track Circuit

RUNNINGRAILS

TWC LOOP(OPTIONAL)

DIRECT COUPLINGUNIT

DIRECT COUPLINGUNIT

INSULATED JOINTS

AF-902/904 TRAIN DETECTIONAND CAB SIGNAL


2-5 SM8051

circuit contains insulated joints. S bond and O bond coupling methods will not function in areaswhere one rail of the track circuits are tied together. Vital commands for speed,coupling/uncoupling, direction, etc., are transmitted to the vehicle via the cab signaling system.Non-vital, bi-directional data, including vehicle health information, diagnostics, and testingcommands, is transmitted via the TWC system. (Please refer to the TWC manual, SM8054.)

2.3 CAB-ONLY TRANSMISSION IN CROSSOVERS

A typical crossover arrangement of a cab-only transmission loop is shown in Figure 2-4, TypicalInterlocking Cab-Only Transmission Loop. A transmission loop is installed within the rails of thecrossover. The loop is transposed approximately every 13 feet (4m) to prevent induced electricalinterference between the cab loop and the rails. The loop is connected to a coupling unit, whichin turn is connected to the output of one of the two transmitter PCB groups. In these crossovers,train detection is done via standard power frequency track circuits.

Note that in certain applications, crossovers may also be controlled by AF902/904 equipment ina direct injection configuration, as shown in Figure 2-3.

6 4

3 5 1 3

2 6

7CU

(TO COUPLING UNITS) (TO COUPLING UNITS)(TO COUPLING UNITS)

(TO COUPLING UNITS) (TO COUPLING UNITS) (TO COUPLING UNITS)

60 HZ

VANERELAY

TOMICROLOK

F F

FF

F

FF

F F

TOSER

Figure 2-4 Typical Interlocking Cab-Only Transmission Loop


2-6 SM8051

2.4 TRAIN DETECTION ONLY IN DOUBLE CROSSOVER

Figure 2-5, Double Crossover (Train Detection Only) shows one specific application for adouble-crossover where only the train detection function is supplied (no cab signal is provided).

DIRECT INJECTCOUPLING UNIT

(TRANSMIT)


(TRANSMIT)


(RECEIVE)


(RECEIVE)

Figure 2-5 Double Crossover (Train Detection Only)

2.5 SYSTEM CONNECTION DIAGRAMS

The AF-902 cardfile is a self-contained unit consisting of the primary track circuit (A) and itsredundant backup track circuit (B). The AF-904 cardfile contains four independent track circuits.

Refer to Figure 2-6a, Inductive Coupling Unit, Terminal Identification for cabling terminalidentification.

Refer to Figure 2-6b, Direct Injection Coupling Unit, Terminal Identification for the cablingterminal identification.

Figure 2-7a, AF-902 Track and AC Connectors and Typical Wiring, illustrates the typical wiringconnections for track circuits1 and 2. Figure 2-7b, AF-902 Typical Serial Link Connections,shows the typical serial link connections between the Microlok II ports and the AF-902connectors.

Figure 2-8, AF-904 Track and AC Connectors and Typical Wiring, illustrates the typicalconnections between the AF-904 connectors and track circuits 1, 2, 3, and 4.


2-7 SM8051

TB1-1

TB1-2

TB1-3

TB1-4

TB2-1

TB2-2

TB2-3

TB2-4

TRANSMITTER 1

TRANSMITTER 2 TRANSMISSION LOOP 1

TRANSMISSION LOOP 2

Figure 2-6a Inductive Coupling Unit, Terminal Identification

GND

Figure 2-6b Direct Injection Coupling Unit, Terminal Identification


2-8 SM8051

Fig

ure

2-7a

AF

-902

Tra

ck a

nd A

C C

onne

ctor

s an

d T

ypic

al W

irin

g


2-9 SM8051

Fig

ure

2-7b

AF

-902

Typ

ical

Ser

ial L

ink

Con

nect

ions


2-10 SM8051

Fig

ure

2-8

AF

-904

Tra

ck a

nd A

C C

onne

ctor

s an

d T

ypic

al W

irin

g


3-1 SM8051

3 FUNCTIONAL OPERATION

3.1 INTRODUCTION

The heart of the AF-902/904 track circuit is a Motorola 68HC16 Micro Controller Unit (MCU).This MCU receives vital asynchronous data from the track MICROLOK II, adds local trackcircuit data, and converts the data into a synchronous protocol (see section 1.3 for a descriptionof this data). The data is then sent to the transit car via the transmitter, transmitter coupler andbonds. The MCU monitors the transmitted signal, via the assigned receiver coupling unit, todetect the presence of a train in the track circuit and reports non-interlocking track circuit trackoccupancy back to the Interlocking MICROLOK II, along with system health and local speedreductions, via an RS-485 serial data link.

3.2 WAYSIDE TO TRAIN MESSAGE FORMATION

The protocol of the AF-902/904 track communications link is an asynchronous, bit-orientedprotocol. This asynchronous protocol dictates that the clocking information (data timing) beembedded in the message. This embedded signal allows proper decoding of the serial data string.

3.2.1 Data Routing

When a signal is received from MICROLOK II, the MCU extracts the data from theMICROLOK II protocol and vitally stores it to Random Access Memory (RAM). The MCUperforms vital logic with the MICROLOK II data and other data stored locally in an ElectricallyErasable Programmable Read Only Memory (EEPROM). Since EEPROMs do not use a batteryto retain their memory when power is removed, they require no maintenance. The only batteryrequirement is for the event logging operation. This EEPROM is mounted on the motherboard sothat when a controller PCB is replaced, no reprogramming is necessary. However, the Maintainerwill need to run the track circuit calibration procedure to verify settings and calculate newthresholds. Each of the four controller PCBs in a cardfile has its own EEPROM. The local dataused by this logic is the unique 12-bit ID number of a given track circuit, and possibly a speedrestriction, which was entered via the switches on the front of the controller PCB. In addition,configuration information for the unit, such as the MICROLOK II slave address, carrierfrequency, track circuit threshold voltages, and any other non-volatile information needed tooperate the AF-902/904, is vitally stored in the EEPROM. If the speed commanded byMICROLOK II is greater than that of the present local speed restriction (if any) the slower of thetwo is used. If the restriction speed is greater than that commanded by MICROLOK II (or is non-existent) the speed commands will be sent as requested by MICROLOK II. Once the propermessage has been constructed, the MCU converts the data into a synchronous protocol, using anNRZI format. As configured, the AF-902/904 uses a 200 baud BFSK carrier to both transmit anddetect the presence of a train in the track circuit.

The digitally formatted message is transmitted to the vehicle using FSK modulation and containsa total of 61 to 72 bits. The FSK modulation process is explained in more detail in Section 3.3.


3-2 SM8051

3.2.2 Data Protocol

The messages delivered to the track by the AF-902/904 system consist of 37 bits of data, an 8 bitheader/synchronization character, 16 bits of CRC and 10 bits of zero insertion or additional fillbits to make a total of 71 bits. The message is formed by appending the 16 bits of CRC to thedata bits, inserting zeros as needed to prevent the uncoded header 0x7E (hexadecimal) fromappearing within the message, inserting fill characters to make the message a fixed length,appending the header to the beginning of the message, and encoding the message using NRZIencoding. The following is a summary of the track message formulation:

Speed: 200 bits per second (200 Baud)

Protocol: Synchronous, bit oriented (similar to SDLC)

Header: 0x7E

Data: 37 bits

CRC: CRC-16

Zero-Bit insertion

Rounding bits to make constant size, 71 bit messages

Encoding: NRZI

Modulation: BFSKA typical bit representation for a message would be as follows:

Header Data Stuffed Bits CRC

8 bits 37 bits 0 to 10 bits 16 bits

61 to 71 Bit NRZ1 Encoded Message (Less Rounding Bits)

3.2.3 Message Commands, Functions, and Formation

The data stream is used for both train detection and instructional messages. The number ofassigned bits and their assigned instructions are shown in the following table.

BITS FUNCTION DEFINITION

13 Track ID - IncludingPrimary/Backup Indication

Allows for separate track circuits

2 Direction Commands the direction of travel

3 Next cab carrier frequency (9.5kHz to 16.5 kHz)

Identifies the upcoming track circuit cabsignaling frequency


3-3 SM8051

BITS FUNCTION DEFINITION

7 Distance-to-go to the targetspeed

Represents the distance to the target speed

4 Line speed (65 to 0 mph in 5mph steps plus 8 mph)

Represents the maximum speed permitted by thetrain within the control line

4 Target speed (65 to 0 mph in 5mph steps plus 8 mph)

Represents the desired speed of the train at theend of the control line

1 Berthed Indicates the vehicle's doors are within thebounds of the usable portion of the stationplatform

2 Couple and uncouplecommands

Used during the make up of trains

1 Bifurcation Used for bifurcation

These messages are used on adjacent track circuits along the entire length of the identified transitline. In order to isolate these commands between track circuits, eight available carrierfrequencies are alternated throughout the transit line. Each AF-902/904 track circuit is assignedone of eight base frequencies. Bits, which are made up of MARKS and SPACES, are identifiedby the frequency they are assigned. The base frequencies and the corresponding SPACE andMARK frequencies are shown in the following table.

Center Frequency (kHz) SPACE Frequency (kHz) MARK Frequency (kHz)

9.5 9.3 9.7

10.5 10.3 10.7

11.5 11.3 11.7

12.5 12.3 12.7

13.5 13.3 13.7

14.5 14.3 14.7

15.5 15.3 15.7

16.5 16.3 16.7

3.3 FSK SIGNAL TRANSMISSION

BFSK is a method of modulating a center frequency which uses two distinct frequencies toconvey the information. One, and only one, of these two frequencies is on at a given time. Aslisted in the preceding table, the higher of the two frequencies is called "MARK" and the lower iscalled "SPACE." The two frequencies are separated by 400 Hz. When combined with the NRZIformat, the result is a signal, which changes its frequency each bit time, to represent a logicalZERO, and continues to transmit the frequency of the last bit time to represent a logical ONE.This means that a string of ZEROs would be represented by a carrier with a frequency that


3-4 SM8051

toggles between MARK and SPACE (or SPACE and MARK) every 5 ms. To send a string of sixONEs, the carrier would remain at MARK or SPACE (depending on the last frequency beforethe first ONE) for six bit times (30 ms).

To make a synchronous protocol practical, a means of recovering the synchronization clock atthe receiving end must be provided. A method similar to that of SDLC is employed. On thereceiving end (the train), a Phase Locked Loop (PLL) is used to extract the clock by synching tothe time between MARK to SPACE, SPACE to MARK toggles. Since, in an NRZI format, along string of ONEs would provide no toggles, a method called "bit stuffing" is used to force atoggle if more than five ONEs are sent. This allows the PLL to remain locked, so it can continueto produce a valid clock signal for the receiving SCC. The bit stuffing is performed at fiveconsecutive ONEs to allow a unique Header byte to frame the message (bit stuffing is notapplied to the header). The header is the same as used by SDLC, logical 0111,1110. Due to bitstuffing, this 0111,1110 pattern cannot appear in the data or CRC part of the message. Thereceiver strips the inserted zeros when the data is decoded.

After manipulating the MICROLOK II and local data into the track protocol, the MCU keys thedata out through the Modulation Numerically Controlled Oscillator (NCO). The ModulationNCO and four other NCOs take a 1.8432 MHz clock and directly synthesize the necessary audiofrequency signals, under software control. The Modulation NCO is programmed with twofrequencies that are 20 times higher than the desired MARK and SPACE frequencies. The MCUthen uses a discrete I/O line to select the frequency needed for the present data bit.

3.3.1 Message Verification

To ensure that the proper message is being sent at all times (even when track occupancy isstopping the receiver from picking up the transmitted message), a frequency monitor circuit isused to check that each bit has the correct frequency. The uniqueness of the signal is contained ina complex digitally coded message, instead of in a simple periodic code rate, which could befalsely generated by an oscillating circuit. Because of this complex code, no further checking isneeded downstream since the "unintelligent" power circuits could never oscillate in a manner soas to produce a valid message. The bit frequency check also serves to detect faulty time bases ineither the MCU internal clock synthesizer or in the 1.8432 MHz clock Integrated Circuit (IC).

From the Modulation NCO, the carrier passes through a digital Pulse Width Modulator (PWM)controlled by the MCU. This PWM divides the incoming square wave into 20 equal parts, andasserts the output for 1 to 19 of the 20 parts. This results in a pulse train with a 5 to 95 percentduty cycle and a frequency of one tenth that of the incoming square wave. The MCU uses thisduty cycle control to make fine adjustments to the transmitted signal level. The duty cycle isselected when the track circuit is set up via a menu option on the controller PCB. The selectedvalue is saved to the motherboard-mounted EEPROM.

The output of the PWM is sent to the auxiliary PCB. On the auxiliary PCB, the carrier is appliedto a flip-flop, which divides the frequency in half and provides two opposing phase signals as itsoutput. These signals are applied to a pair of high-current, high-speed Field Effect Transistor(FET) drivers, which boost the signal up to the levels needed to properly drive the four powerMOS FETS that form the full bridge power amplifier. The power amplifier gets its "B+"


3-5 SM8051

(approximately 44V dc) from an onboard rectifier and voltage regulator. A nominal 48V ac forthis supply comes from transformers mounted on the rear of the cardfile. These transformersisolate and step down the 120V ac mains. Two transformers are used for each controller-auxiliary PCB pair (8 per cardfile) to provide good power supply margins.

The output of the power amplifier is fed to the output transformer. This transformer has fivesecondary taps which provide coarse transmitter level adjustment. The transformer also has anauxiliary winding which is used to monitor the transmitter output level. When transmitting aBFSK message, the signal has almost a constant power output. To ensure that the transmittedlevel does not increase (due to a failure of the B+ regulator, the PWM, or anything else) thesignal from the monitor winding of the output transformer is rectified and averaged. Theresulting DC voltage is read by the MCU Analog to Digital Converter and checked to make surethat it falls within a preset value. If the voltage is outside of this range, the track circuit ClearSignal is dropped, and the unit transfers control to the standby unit. The range for the poweramplifier monitor is set during unit configuration. After the track circuit has been properlyadjusted, the Installer selects a menu command which measures the voltage coming from thepower amplifier monitor, adds a fixed tolerance to it, and vitally stores this range (window) awayto EEPROM.

The taps of the output transformer secondary are selected using jumpers on the motherboard, sothat when a PCB is replaced no adjustments are necessary, except for signal level calibration. Onthe common side of the secondary is a relay, which can isolate the output from the rest of thesystem. This form "C" relay is wired to use only the normally open contact set. The relay iscontrolled by switched power from the CPS so that if the CPS is dropped, the contacts open. Theswitch is used to allow the contacts to be open when the CPS is up. This is necessary so that theoff-line unit may run diagnostic tests on its transmitter circuits. The switch is controlled by theMCU via an I/O port, which also drives the seven LED indicators on the auxiliary PCB.

After leaving the cut-out relay and selector taps, the two output leads are routed through a set ofdirection relays. These are Hengstler safety-style relays with check contacts that indicate thestatus of the main contacts. If the check contacts are closed, then the main contacts areguaranteed to be open. By monitoring the check contacts, the controller PCB ensures that onlythe correct direction relay is energized.

3.3.2 Equipment Room To Rails

From the relay/equipment room, track leads of up to several kilometers total loop length connectthe trackside coupling units to the direction relays. The track leads are twisted pairs with anintrinsic impedance (Zo) of approximately 100 ohms. The coupling units are housed in weathertight enclosures, and consist of two totally independent and isolated coupling circuits. Eachcircuit has its own transformer and capacitor bank. The transformer steps down the high voltageon the leads from the relay room to a low voltage suitable for driving the single turn track loop.The capacitors are jumper-selected to tune the track loop.

This tuning raises the reactance of the track loop to the selected carrier frequency. This raisestransmitter efficiency since smaller currents are required to flow in the long track leads.Likewise, when a track loop has been selected to be a receiver, the low voltage from the track


3-6 SM8051

loop is stepped up to drive the leads back to the relay room. The tuning of the track loopprovides a small increase in received signal strength. Due to the differences in transmitter andreceiver impedance, the coupling unit is adjusted, so as to provide some benefit to bothtransmitter and receiver. The tuning is necessarily very broad and does not result in anyappreciable frequency selectivity between the jointless track circuits.

The AF-902/904 does not use a conventional impedance bond. Instead, a few meters of 350 or500 MCM cable is connected between the two rails in an "S" shape, with an end of the "S"bonded to each rail. Single turn track loops are mounted inside of the upper and lower parts ofthe "S." Currents circulating in the transmitting track loop are induced into the "S" and onto thetrack. Likewise, currents from the track circulate in the "S" and are induced into the receivingtrack loop. This type of bond has a strong directionality, with the ratio of the length to the widthof the "S" determining the directivity (like the front to back ratio on an RF directional antenna).Which track loop does the transmitting or receiving is determined by the direction relays locatedon the rear of the cardfile.

3.4 TRAIN DETECTION

Each AF-902/904 system vitally monitors the status of a single track circuit. The FM, audiofrequency carrier that is transmitted at one end of the track circuit and received at the other end,is used not only for the digital cab signal data, but also for train detection. The carrier level and apart of the digital message are monitored by the receiver to determine track occupancy.

When a train shunts the rails of the monitored track circuit, the signal is blocked. This conditionis recognized by the receiving AF-902/904 circuits as a drop below a preset signal threshold, andis reported to the associated interlocking MICROLOK II system as an occupied circuit. Whilethe shunting train bridges adjacent track circuits, both are reported as occupied. When the trainclears a track circuit, the received signal threshold is restored and the AF-902/904 systemresponds accordingly.

3.4.1 Signal Level Sensing

From the selected receive cable, the returning signal passes through a disconnect relay beforebeing applied to the receiver transformer. This relay is also wired to operate in a normally openmanner, and is closed only when the CPS for the unit is up and the MCU has switched on therelay. The receiver disconnect relay is controlled by the same switched CPS power as thetransmitter disconnect relay. A single relay could not be used due to the safety requirement ofpreventing a direct short between the transmitter and receiver.

The receiver transformer has five taps. These taps allow the AF-902/904 to be adjusted fordifferent operating conditions, such as track lead length, direct inject vs. bond injection, and loopdriving without a bond. The selected tap is clamped by a tranzorb to protect the receiver circuits.

3.5 MONITORING AND FAILOVER

Since the AF-902/904 track circuit unit is an interface between the MICROLOK II system andthe trackside equipment, it is necessary to monitor the vital communication data and hardware


3-7 SM8051

performance. This requires that the communications between the MICROLOK II unit and theAF-902/904 unit is functioning properly and that the internal data processing of signals withinthe AF-902/904 is also functioning properly. This also requires that the data or signals levels toand from the rails are accurate and available to the cab.

3.5.1 MICROLOK II Monitoring

The MICROLOK II unit acting as the protocol master monitors various aspects of the datacommunication link between the AF-902/904 unit and itself. AF-902/904 faults pertaining toincorrect message contents, message length, or response time will result in a system error andcause the message to be discarded. Additional fault details are described in Section 7.

3.5.2 AF-902/904 Monitoring

The AF-902/904 unit must monitor the communications link between the MICROLOK II unitand itself, internal reliability, and the transmit and receive signals to the rails.

3.5.2.1 MICROLOK II RS-485 Communications Link

The following is a set of possible fault conditions that could be detected by an AF-902/904system acting as a protocol slave unit. The faults pertain to master polling messages sent by theMICROLOK II unit to the AF-902/904 system.

Timeouts If an AF-902/904 system does not receive a poll from theMICROLOK II in 3 seconds, it will declare the link to bedown.

CRC Mismatch If a CRC does not match for a message received fromMICROLOK II, the AF-902/904 system will discard theinvalid message.

Incorrect Length If a response message from the MICROLOK II is either toolong or too short because of any data bytes or CRCmismatch, the incomplete message will be discarded.

No Acknowledgment If an acknowledgment indication is not received by the AF902/904 system from MICROLOK II, the AF-902/904system will declare the link to be down.

3.5.2.2 AF-902/904 Cardfile Unit

Each AF-902/904 subsystem must pass its own continuous internal diagnostics. In the event of afailed vital diagnostic, the controlling microprocessor stops transmitting a 500 Hz vital signal tothe subsystem CPS on the auxiliary PCB. When this signal is removed, the CPS shuts down,preventing cab signal data transmission and indications of a clear track. In AF-902 systems, ifthe primary track circuit controller fails, the backup track circuit automatically switches intooperation. This automatic failover is transparent to the operation of the system.


3-8 SM8051

3.5.2.2.1 Transmit Data Monitoring

To ensure that the proper message is being sent at all times (even when track occupancy isstopping the receiver from picking up the transmitted message), a frequency monitor circuit isused to check that each bit has the correct frequency. Because of this complex code, no furtherchecking is needed downstream since the "unintelligent" power circuits could never oscillate in amanner so as to produce a valid message. The frequency check also serves to detect faulty timebases in either the MCU internal clock synthesizer or in the 1.8432 MHz clock IC.

3.5.2.3 Receiver Systems Monitoring

The AF-902/904 unit is constantly transmitting to the track circuit for occupancy or broken railindications. These transmissions are also used to verify and monitor the accuracy and integrity ofthe data and signal levels.

To ensure that the receiver systems are operating correctly, a test signal is added to the tracksignals just before the input BPF. This signal is of known frequency and amplitude and, as such,must fall within a fixed range when monitored on the designated test channel. All three receiversare checked by reprogramming their NCOs at the end of each message, in the following manner:

ReceiverChannel

Functionat MSG1

Functionat MSG2

Functionat MSG3

Functionat MSG4

Functionat MSG5

Functionat MSG6

1 Mark Space Test Space Mark Test

2 Space Test Mark Mark Test Space

3 Test Mark Space Test Space Mark

The source of the test signal is an NCO located on the auxiliary PCB. This NCO is set to afrequency other than that of the MARK or SPACE used in the track circuit. The NCO drives ananalog switch that chops a DC voltage from the TEST Digital to Analog Converter (TESTDAC). By changing the TEST DAC output, amplitude of the test signal can be changed.

Once the MCU has determined that the track circuit is clear, unoccupied and unbroken, it assertsthe vital output on the MICROLOK II. The vitality of the output is accomplished by switchingoff the output transistor and measuring the output voltage. If more than a predetermined voltage(to account for leakage currents) is preset, the MCU shuts down the CPS. With the CPS dropped,there is no power source for the output circuit. All control and monitor lines to the vital outputcircuit are of very high controller PCB. This output switches CPS power OFF or ON to a vitalinput on the interlocking impedance, so they cannot pick or hold-up the MICROLOK II vitalinput.

To ensure that the voltage measurement is accurate, a test voltage is summed in with the voltageon the vital output. By varying the known test voltage, a predetermined offset should occur in themeasured voltage. If not, the gain check will fail and the MCU will drop the CPS.


3-9 SM8051

A non-vital, normally open disconnect relay allows the vital output to be tested on the standbyunit. Power for the coil of this relay is provided by the CPS, so that a coil to contact short willnot be able to assert the output when the CPS is dropped. As a check that this non-vital relay isclosed when the unit is online, an independent non-vital circuit checks that when the vital outputof the online unit is on, voltage is present on the line to MICROLOK II. A diode is used toisolate the relay from the wire to the MICROLOK II so that if the relay should fail to open, it willnot prevent the back up unit from driving the line. If both the relay and the diode fail, the system isstill in a safe state since a low signal on this line indicates track occupancy.

3.5.3 Failover (AF-902 System Only)

The CPS is a class 1 vital circuit that only produces power when a 500 hertz square wave isprovided to it from the MCU. The MCU runs many complex diagnostic tasks on itself and on therest of the AF-902 unit. These test range from testing of CPU memory and logic processing tofull closed-loop tests of the vital output, transmitter and receiver circuits. If any of thesediagnostics fail, the MCU stops toggling the 500 Hertz line and the CPS drops out. The CPS isthe sole power source for the vital output, and the modulation oscillator clock source. When theCPS is dropped, the unit cannot transmit or indicate a clear track, no matter what the failure. TheCPS also has a non-vital output which provides power for the disconnect relay coils, except forthe relay that disconnects the vital output. The vital output relay gets its coil power from the vitalsupply, so that a coil to contact short will not be able to energize the circuit when the CPS isdown. If the CPS is down, all coils lose power and the AF-902 unit drops off-line. The CPSinterlock on the disconnect relays makes it very unlikely that a failed unit could keep its standbyunit from restoring proper operation to the track circuit. However, even if a disconnect relaywere to become welded in the closed state, the design of the circuits is such that no safetyproblems will arise since the CPS vitally removes power from the vital class 2 circuits.

AF-902 units have been configured to provide full redundancy for each individual track circuit.Each 19-inch (48.26 cm) cardfile can house the electronics for two track circuits, with each trackcircuit having two controller/auxiliary PCB pairs and a common power supply PCB. The powersupply PCB has two independent supply systems, with switches to cut the ac mains for each.Each supply provides +15V dc, +5V dc, -15V dc and a nominal 48V ac. The two-track-circuitcardfile is wired such that the two primary units are powered by one 120V ac main, and the twobackup units are powered by a second independent 120V ac main.

The left controller/auxiliary PCB pair of each track circuit is called the primary, and the rightpair is called the backup. These terms refer to the physical placement of the PCBs. Whicheverunit is operating the track circuit is called the online unit, the other unit is called the standby unit.This logical distinction is needed because a failed or powered-off primary unit could be replacedand/or powered up, without it becoming the online unit. The primary unit will remain thestandby unit until either the power is cycled to both units or the backup unit fails.

When the AF-902 units are simultaneously powered up and operating properly, the primary pair(left) is the online unit and the backup pair (right) is the standby unit. The hard-wiring on themotherboard determines which AF-902 unit is the primary unit and which AF-902 unit is thebackup unit. The standby unit is up and running the same software as the primary unit, exceptthat it is isolated by the disconnect relays. The two units communicate to each other through a


3-10 SM8051

dedicated serial link. Two DC lines cross link the primary MCU to the backup CPS, and thebackup MCU to the primary CPS, to provide a second check on the health of each unit. Astandby unit will not try to go on-line unless it is not receiving communications from the oldonline unit and it has detected that the old online unit CPS is dropped. If this happens, thestandby unit will become the online unit, the old online unit will be off-line and the new onlineunit will inform MICROLOK II that the track circuit is not healthy. The health bit in theMICROLOK II message is only set when both primary and backup units are working properly. Ifthe online unit stops receiving communications from the standby unit or detects that the standbyunit CPS is dropped, it informs MICROLOK II that the track circuit is not healthy. A Maintainershould be dispatched to correct the problem whenever the health bit is not set.


4-1 SM8051

4 FRONT PANEL MENU OPERATION

4.1 INTRODUCTION

The front panel menu system of the AF-902/904 unit is used to modify and display vital and non-vital system parameters and to execute system functions. Any Operator can access any menufunction, except for the configuration functions, which can be accessed only by authorizedOperators. The operation of the switches is consistent across all functions.

4.2 FRONT PANEL DISPLAYS AND CONTROLS

The menu control system consists of two, four-character alphanumeric scrolling displays andfour up-down SPDT toggle switches that are used to enter and examine data used in the set-upand operation of the track circuit. Five LEDs provide additional information. In addition, a frontpanel PC-compatible serial port and a background mode debugging port are available. The serialport can be made available to the end user, but the background port is for factory use only.Figure 4-1, Controller PCB Front Panel, shows the switches and displays as well as thecorresponding names and identification.

4.2.1 Displays

The display section is composed of two four-character alphanumeric displays and five LEDs.The upper display is red and the lower display is green.

The upper display is wired so as to prevent an address decode failure. This wiring methodprevents both displays from displaying the same data.

There are four system monitoring LEDs on the controller PCB that are controlled by threedifferent sources. These LEDs are mapped as shown in the following table:

Controller LED Significance whenOn

Significance whenOff

Significance whenFlashing

W WEST/NORTH/NORMAL relayPICKED

WEST/NORTH/NORMAL relayDROPPED

WEST/NORTH/NORMAL relayPICKEDTRACK SHUNTED

E EAST/SOUTH/REVERSE relayPICKED

EAST/SOUTH/REVERSE relayDROPPED

EAST/SOUTH/REVERSE relayPICKEDTRACK SHUNTED

1 FAILOVER linkGOOD

FAILOVER linkBAD

N/A

2 CONFIGURATIONMODE

ONLINE orSTANDBY mode

UNCONFIGURED orERROR-TRAP mode


4-2 SM8051

UP

DOWN

ADJMODE

AUX 1

PRESS TORESET

IN RESETWHEN LIT

ESCAPE

STATUSLEDS 2

1

DIR.

W

E

DEBUGPORT

TRK CKTCTRLR

N123603- 01

DIAGPORT



(FACTORY USE ONLY)




SYSTEM MONITORLEDS


9-PIN PORTFOR



ENTER AUX 2

Figure 4-1 Controller PCB Front Panel


4-3 SM8051

4.2.2 Controls

Each menu of the AF-902/904 system uses the control switches for the following purposes:

Mode Up Scrolls forward through selections or display parameters.

Mode Down Scrolls backward through selections or display parameters.

Adjust Up Increases the current parameter. Where appropriate, whenthe maximum value is reached, the parameter rolls over tothe minimum value. In the Display submenus, the AdjustUp switch is used to modify the display code.

Adjust Down Decreases the current parameter. Where appropriate, whenthe minimum value is reached, the parameter rolls over tothe maximum value. In the Display submenus the AdjustDown switch is used to modify the display code.

Enter Enters a submenu or confirms a parameter value.

Escape Backs out of a submenu or cancels an operation.

Aux. 1 Enters the blocking speed menu. This switch has no effectfrom the restricted access menus. (Same as Aux 2.)

Aux. 2 Enters the blocking speed menu. This switch has no effectfrom the restricted access menus. (Same as Aux 1.)

4.3 FRONT PANEL OPERATION

On-site set-up of operating parameters is accomplished using the front panel controls anddisplays. Parameter adjustments available on the AF-902/904 system include:

• Unique 12 bit track circuit ID (number between 1 and 4095)

• Slave address for MICROLOK II serial link

• Transmit carrier frequency and signal strength

• Train detection threshold voltage

• Blocking Speed restriction (when required)

• New password

All of the parameter set-up functions, except Blocking Speed, are password-protected.

Controller PCB displays and controls also permit real-time examination of data received fromthe track MICROLOK II system and the monitored track circuit, including:

• Current line and target speeds

• Target distance


4-4 SM8051

• State of berthing data bit

• States of east/west direction-of-travel data bits

• States of couple/uncouple data bits

• Next transmit frequency

• Current track circuit ID number

• Bifurcation bit

Detailed monitoring and diagnostics of the AF-902/904 logic and memory can be performedusing a portable PC plugged into a 9-pin serial port on the front of the controller PCB frontpanel. The portable PC may use any standard terminal emulation software.

4.3.1 Front Panel Menu Interface

The front panel menus are divided into two categories, restricted and unrestricted, based onaccess privileges. In addition to access restrictions, there are several other properties thatcharacterize the operation of the AF-902/904 interface, including password entry, cardfileconfiguration, key repeat rate, key repeat delay, and time-out.

4.3.1.1 Restricted Access Menu

The Configuration submenu is a restricted access menu that can be used only by an authorizedOperator to configure critical system parameters (restricted access parameters). Erroneous entryof restricted access parameters may cause the system to behave in an unsafe manner. It istherefore necessary that these parameters be configured only by qualified personnel. Restrictedaccess parameters can be modified only after a password is entered, and the modified parameterscan be made operational only after the password is reentered and all changes are confirmed.When an Operator enters the Configuration submenu, both the online unit and the standby unitsuspend normal operations. The online unit suspends track transmission and MICROLOK IIresponse, and all outputs on both units are put into a safe state. Normal operation resumes onlyafter the system is reset.

4.3.1.2 Unrestricted Access Menus

Unrestricted access menus permit an Operator to perform functions that cannot result in unsafesystem operation. All of the system submenus, except the Configuration menu, are consideredunrestricted access menus.

4.3.1.3 Password Protection

In order to enter the Configuration menu and to save modified parameters, a password isrequired. Entering the password is similar to modifying the track ID number, and is described inSection 5.4.5.1. The default password can be modified via the Password Modification menu.


4-5 SM8051

4.3.1.4 Cardfile Configuration

When a restricted access parameter is changed, it must be changed to the same value in both theprimary and backup units in an AF-902 system. The only exception is the Blocking Speedsetting. This value is communicated between the primary and backup unit, with the most recentlyset value communicated to both units. If the primary and backup have different values at startup,the most restrictive (lowest) speed will be used by both units. Since the AF-904 does not have abackup unit, this function does not apply.

4.3.1.5 Key Repeat Delay

If a key is held in the same position for longer than the key repeat delay, it will begin to repeat atthe key repeat rate. The key repeat delay is set to 2/5 second. The key repeat rate is set to 5 persecond.

4.3.1.6 Time-out

To prevent unauthorized Operators from using the Configuration menu, the system willautomatically time-out if this menu is active and 20 minutes have passed without the Operatorpressing a switch. The system will automatically reset, and any changes that may have beenmade to the system parameters will be lost.

4.4 MENU HIERARCHY

The menus are arranged in a hierarchical manner. The Main menu is used to select varioussubmenus, from which it is possible to display and modify specific system parameters. Figure 4-2, Menu System Hierarchy, at the end of this section, shows the menu hierarchy. The remainderof this section describes each menu. The hierarchy of the text in this section matches thehierarchy of the diagram.

4.4.1 Main Menu

This menu is used to select a top level submenu. The following submenus are available from theMain menu: Display, Blocking Speed, Events, and Configuration. These submenus are describedin more detail below. Since the Main menu is at the top of the hierarchy, the Escape switch hasno effect from this menu.

4.4.2 Display Menu

This menu contains submenus that can be used to display current system information. Thefollowing submenus are available from the Display menu: MICROLOK II Message, TrackMessage and System Parameters. The Escape switch will move out of any Display submenu.

4.4.2.1 MICROLOK II Message

This menu contains submenus that can be used to display the current message to MICROLOK IIfrom the AF-902/904 and the current message from MICROLOK II to the AF-902/904.


4-6 SM8051

4.4.2.2 Track Message

This menu contains submenus that can be used to display the following information:

• Current message that is being delivered to the track by the AF-902/904 (Transmitmenu).

• Level of the received signal as a percent of the threshold (Receive menu, SignalStrength (STR) submenu).

4.4.2.3 System Parameters

This menu can be used to display the current system parameters. The following parameters aredisplayed: block speed, MICROLOK II address, track ID, primary/ backup, frequency,configured transmit power West, and configured transmit power East.

4.4.3 Blocking Speed Menu

This menu can be used to select the Blocking Speed Adjust submenu from which it is possible toset or modify a blocking speed. This menu also can be immediately reached from anyunrestricted access menu by pressing the Aux Up/Aux Dn switch.

4.4.3.1 Blocking Speed Adjust Menu

This menu is used to set a blocking speed. The Adj Up/Adj Dn switch modifies the current value(the value displayed on the lower display), and the Enter switch is used to enter the value. TheOperator must then confirm the value by pressing the Enter switch again, or reject the value bypressing the Escape switch to exit.

4.4.4 Events Menu

This menu can be used to select a submenu from which it is possible to display events andmanage the event logging system. The following submenus are available from the Events menu:View Events, Clear Events, and Dump Events.

4.4.4.1 View Events Menu

The View Events menu allows the maintainer to view in reverse order the event numbers loggedby the AF-902 / AF-904 system.

4.4.4.2 Clear Events Menu

The Clear Events menu will erase all recorded event numbers from the AF-902 / AF-904memory.

4.4.4.3 Dump Events Menu

Selecting the Dump Events menu will cause the event data to be transmitted to a serial datacommunications terminal connected to the front panel "DIAG PORT."


4-7 SM8051

4.4.5 Configuration Menu

This menu contains submenus that are used to modify system parameters. The Password Entrysubmenu allows the user to enter the password. The Restricted submenu contains other submenusthat allow the user to modify critical system data.

4.4.5.1 Password Entry Menu

This menu is used to enter and validate the restricted access password. The four-characterpassword is entered one character at a time. The active character flashes, while inactivecharacters are displayed constantly. Initially, "AAAA" is displayed and the leftmost character isactive. The Adj Up/Adj Dn switches are used to advance the active character through theelements of the password character set. The Enter switch selects the current value of the activecharacter and activates the next character.

4.4.5.2 Restricted Menu

This menu is used to select a restricted access submenu. If the proper password has not beenentered using the Password Entry menu, the submenus of the Restricted menu are not available.To enter the restricted access menus, the AF-902 / AF-904 will automatically go through a resetcycle. If there is a backup unit in an AF-902 system it must be turned off prior to entering theRestricted menu.. The following sections describe the submenus that are available from theRestricted menu. Exiting from the Restricted menu will cause the unit to reset. After the resetthree menu selections are available: Set-up, Utility, and Accept.

4.4.5.2.1 Set-up Menu

Selecting this menu, by pressing the Enter switch, will make four submenu selections availableto the Maintainer: Tune, MICROLOK II, ID, and Calibration.

4.4.5.2.1.1 Tune Menu

The Tune submenu is used to configure the AF-902 / 904 for train detection and cab signaling.The Tune menu contains several sequential submenus that are to be used in conjunction with thetrack circuit set-up and tuning procedure. Due to the sequential nature of the tuning procedure, amenu item may have both a function and a submenu.

The Frequency Adjust menus are used to change the carrier frequency in either the West to Eastor East to West signal transmission direction. The Adj Up/Adj Dn switches are used to modifythe value that is displayed, and the Enter switch moves to the Power Output menu.

The Power Output menus are used to adjust the power of the transmitter. The Adj Up/Adj Dnswitches are used to modify the value that is displayed, and the Enter switch moves to thesubmenu.


4-8 SM8051

4.4.5.2.1.2 MICROLOK II Menu

This menu is used to select the MICROLOK II Address Adjust submenu, which can be used tochange the MICROLOK II station address.

4.4.5.2.1.3 ID Menu

The Track ID menu is used to enter the track identification number (1 to 4095).

4.4.5.2.1.4 Calibration Menu

The Calibration menu is used to set the operating parameters of the AF-902 / AF-904 system.The function and use of each submenu is described in Section 6 of this manual.

4.4.5.2.2 Utility Menu

This menu can be used to access two submenus: New Password and Clear Configuration(operating parameters).

4.4.5.2.2.1 New Password Menu

The New Password function allows the user to change the default password. The password ismodified using the Adj Up/Adj Down switches, and the Enter switch sequentially confirms eachcharacter. The Escape switch backs up by one character or cancels the operation if the firstcharacter is displayed. After the password has been entered, the user is asked to confirm thevalue. A password that is modified and then confirmed immediately becomes the systempassword. The default password can only be restored by physically replacing the EEPROM onthe motherboard.

4.4.5.2.2.2 Clear Configuration Menu

This function allows the maintainer to erase all configuration parameters of the AF-902/904system. Attempting to operate the system after this selection is made will cause the system toenter the unconfigured mode.

4.4.5.2.3 Accept Menu

This menu is used to confirm the changes that have been made to the restricted access systemparameters. The Accept menu is a group of menus that sequentially prompt the maintainer toconfirm the modifications that have been made to the system parameters. The parameteridentifier is displayed first followed by the new value shown on both the top and bottomdisplays. The Operator must press either the Enter switch to confirm that both displays indicatethe correct parameter or the Escape switch to abort the modification. After each modifiedparameter has been confirmed, a Password Entry menu is activated. This menu is similar to themenu described above. If the correct password is entered, the system parameters are written tothe system EEPROM and will be used for all subsequent operation.


Figure 4-2, Menu System HierarchySM8051, 4-9, 4-10

MAINMENU

BKSPMENU

DISPMENU

EVNTMENU

Cancel

bksp.35

CON-FIRM

.35

.35

DeniedDone

Denied

SYSMENU

MLOKMENU

TRKMENU

bksp35Mlok

1TkID2199

PrimYes

Freq13.5PwrW10%PwrE10%

E W1 0Nxfq15.5

TD9000

LS65

TS65Brth

0Cpl0

Denied

Ucpl0Bifr0

TXMENU

RXMENU

Bkspset

Hlthok

Trkok

E W1 0Nxfq15.5

TD9000

LS65

TS65Brth

0Cpl0Ucpl

0Bifr

0

RXMENU

TXMENU

Strxxx%

VIEWEVNT

CLREVNT

DUMPEVNT

#170033

#160059

#10033

Done Done

DISPMENU

CNFGMENU

pswdAAAA

PSWDMENU

WAIT

Cancel

Cancel

Invalid SystemReset

SystemReset

RSTRMENU

SETUP

ACPTMENU

UTILMENU

NEWPSWD

pswdAAAA

CON-FIRM

CLRCNFG

Sure?

11

TUNEMENU

CALIBRAT

freq13.5

Cancel

IDMENU

TkID2199

Cancel

MLOKMENU

addr1

Cancel

DIRW->E

freq10.0

Cancel

DIRE->W

freq10.0

Cancel

Invalid

WAIT

Deniedpwr10%

Denied

WAIT

WAIT

Deniedpwr10%

Denied

WAIT

Cancel

Cancel

MlokAddr

21992199

TkID

AAAAAAAA

NewPswd

PrimPrim

PrimBkup

13.513.5

Freq

10%10%

PoutW->E

10%10%

PoutE->W

pswdAAAA

WAIT

DoneDenied

Invalid

Sure?

DIRW->E

WAIT

pwr10%

DIRE->W

WAIT

pwr10%

Denied

Denied

Levl95%

Vari2% Denied

Shnt70%

DIRW->E

WAIT

Levl98%

Vari2%

Shnt70%

WAIT

AC-CEPT Denied

Denied

Denied

Crsp0

Invalid

WAIT

(To Accept Menu)

A

B

AF-902 / AF-904 Menu System Navigation

Move from menu "A" to menu "B" bydepressing the "Enter" switch

A

B

Move from menu "B" to menu "A" bydepressing the "Escape" switch

A B Move "left/r ight" with the "Mode - Up"and "Mode - Down" switches

A dashed line indicates the move will happenautomatically when the task is completed

Note: When a menu al lows a value to be adjusted, press the "ADJ - Up" toincrease the value and "ADJ - Down" to decrease the value.

A0

B0

Move between stacked information menus withthe "Mode - UP" and "Mode - Down" swi tches

This page is intentionally blank.


5-1 SM8051

5 INSTALLATION AND ADJUSTMENT

5.1 INTRODUCTION

The track circuit installation and adjustment depends on the assigned block frequency and trackcoupling methods.

Installation procedures should be in accordance with those recommended by the equipmentmanufacturers for any equipment that is interfacing with the AF-902/904 unit. Each installationrequires cable interfacing for the assigned system. Refer to the specific site plans for detailedinstallation and track coupling requirements such as track circuit lengths, frequency assignments,track circuit identifications, and wiring sheets.

5.2 RECOMMENDED TEST EQUIPMENT

The following equipment is recommended for use in testing the AF-902/904 unit:

• A Fluke 8060A with a Fluke 80i-1000s Current Transformer calibrated for themeasurement range of 40-150ma ac (rms) and documented.

• AAR Style 1/2 in. hex socket wrench used for loosening/tightening AAR standardterminal posts.

• Red tags for identifying failed PCBs.

• Two VOLTREX 855-B Insulated Tip Plugs for PCB Front Panel test probes.

• Handheld radios with 2-mile (3.2 km) range minimum.

5.3 SERIAL LINK CONFIGURATIONTypically, a MICROLOK II communicates to multiple AF-902/AF-904 units through a multi-drop RS-485 link. Terminating resistors must be connected at the physical end of the link, i.e. atthe AF unit farthest from the MICROLOK II. Connecting the terminating resistors at the endunit is accomplished by closing the four SW1 rocker switches located on the back of the AFmotherboard (refer to Figure 5-1). Otherwise, the four SW1 rocker switches should remainopen.

5.4 INITIAL POWER CHECKS

Because of the large dynamic range imposed by the needs of different track circuits, the AF-902/904 Control cardfile incorporates five adjustable transformer taps for both track receivercircuits. These allow for variables such as different track lead lengths. Adjustments are made viajumpers on the cardfile backplane so that a system reset is not required with changeout of thetrack interface circuitry.

Output power is varied by two means:


5-2 SM8051

• Coarse: Output Transformer Taps (1 through 5) on back of the AF-902/904motherboard. Taps act to double output amplitude with each increased setting.(TXA= Primary; TXB = Backup)

• Fine: Pulse width, the "ON" duty cycle percentage of a Full Cycle. Set from frontpanel 'PWR' menu.

5.5 TUNING PROCEDURE

Installation of the track circuit requires a "set-up" procedure. This procedure is comprised of twoalignment procedures. The first of these procedures is called the "tuning procedure."

Tuning is performed first, in order to tune the two associated coupling units to the desired trackcircuit frequencies. These frequencies range from 9.5KHz to 16.5KHz in l kHz increments.

Specific steps and details of the tuning procedure are given in Table 5-3.

5.6 CALIBRATION PROCEDURE

The second of the "set-up" alignment procedures is called the "calibration procedure". Thisprocedure must be performed after the tuning procedure, since it is affected by the resultingtuning signal levels.

Specific steps and details of the calibration procedure are given in Table 5-4.

Tuning is done at the coupling units mounted near the track bond. The coupling unit containstwo identical circuits, which are separated by a dashed line down the middle of the PCB. TheOperator should take care in determining which of these circuits is to be tuned beforeproceeding.

NOTE

The following procedures distinguish the two identical circuits byusing standard text for the left unit circuit, and {BRACKETS} forthe {RIGHT UNIT} circuits.

Tuning affects both the transmitted and received signal levels,making it MANDATORY that the tuning procedure be performedfirst as part of the set-up routine.

For preventive maintenance purposes, since the system isoperational and tuning has been completed at some earlier date,calibration alone can be performed as the sensitivity check.However, if calibration is marginal, it may be necessary toperform both the tuning procedure and calibration procedures.


5-3 SM8051

5.6.1 Testing Codes and Abbreviations

5.6.1.1 Controller Board Display Abbreviation Codes

Basic character and case assignments used for performing the test procedures are as follows:

[AAAA] Upper Menu or Command

[Aaaa] Label Parameter

[BKSP] Block Speed

[MLOK] MICROLOK II

[TUNE] Tuning Procedure

[Levl] Input Rec Level

[CALI] [BRAT] Calibration Procedure

[Shnt] Shunted w.r.t./Levl

[MLOK] MICROLOK II Address Set Menu

[aaaa] Changeable Parameter

[ID] Track Circuit ID Set Menu

[tkid] Track Circuit ID Parameter

[PSWD] Password

[pwr] Output Pulsewidth

[RSTR] Restricted Menu

5.6.2 Test Equipment And Tools

The equipment and tools required for the tuning and calibration procedures are listed below. TheTest Engineer should select the appropriate tools for the required test procedure.

• An HP3560A Dynamic Signal Analyzer with a Fluke 80i 1000s, Current Transformercalibrated for the measurement range of 40-150ma ac (rms) and documented.

• AAR style 1/2 inch hex socket wrench, used for loosening and tightening AARstandard terminal posts.

• Red tags for use in identifying failed PCBs or components.

• Two VOLTREX 855-B Insulated Tip Plugs for PCB front panel test probes.

• Handheld radios with a 2-mile (3.2 km) range minimum.

• Track Shunt 0.25 ohms total resistance. The track shunt resistor itself is 2 ohms and theleads to the rails are 0.05 ohms.


5-4 SM8051

5.6.3 Transmit Power Adjustments

During the test procedure, it may become necessary to adjust the output power in order to meetspecifications. Output power can be varied by two means:

Coarse: Referring to Figure 5-1 AF-902/904 Upper Cardfile RearViews, the Output Transformer Taps (1 through 5) on backof the AF-904/904 motherboard are selected by means ofjumper wires connected between the numbered taps andSignal Common points (labeled COM for AF-902, and R1through R4 and T1 through T4 for AF-902). Taps act todouble the output amplitude with each increased setting.(TXA=Primary; TXB=Backup)

Fine: Pulse width, the ON duty cycle percentage of, in 5%increments from 25 to 95% of Full Cycle. This is set fromthe front panel 'pwr' menu. It is done during the calibrationprocedure, and can be done only after the Operator hastraversed the Configuration menu with the correct password.There is a separate pulse width setting for each direction oftrack circuit transmission. After these are SET andACCEPTED, they are stored in EEPROM.

Figure 5-1 AF-902/904 Upper Cardfile Rear Views

TRACK 4

RX

4 5

4

3

2

1

R4

5

4

3

2

1

T4

TX4

TRACK 3

RX

3 5

4

3

2

1

R3

5

4

3

2

1

T3

TX3

TRACK 2

RX

2 5

4

3

2

1

R2

5

4

3

2

1

T2

TX2

TRACK 1

RX

1 5

4

3

2

1

R1

5

4

3

2

1

T1

TX1

SW1R

XB 5

4

3

2

1

5

4

3

2

1

COM

RX

A

TXB 5

4

3

2

1

5

4

3

2

1

TXA

TXB 5

4

3

2

1

5

4

3

2

1

TXA

RX

B 5

4

3

2

1

5

4

3

2

1

RX

A

SW1

TRK2

COM COM COM

AF-904 Upper Cardfile Rear View

AF-902 Upper Cardfile Rear View

TRK1

J4

J3

1

1

J4

J3

1

1

TRK3&4 TRK1&2

J11

J11

J2

1

J2

1

.


5-5 SM8051

5.6.4 Set-up Overview

There are several parts to the set-procedure, as described in the following subsections.

5.6.4.1 350 or 500 MCM Bond Set-Up Procedure

To set-up the AF-902/904 using a 350 or 500 MCM Bond in either an "S" or "O" configuration,follow the procedure given in Tables 5-1, 5-2, 5-3 and 5-4, and use the Data Sheet at the end ofthis section. Setting the MLOK address and the track circuit ID (Table 5-2) can be performed atany time in the sequence. Tuning (Table 5-3) must be performed before calibration.

5.6.4.2 Cab Loop Set-up Procedure

Follow the procedure in Tables 4-1 and 4-5, and use the data provided at the end of this section.Setting the MLOK address and track circuit ID (Table 5-2) can be performed at any time in thesequence. The AF-902/904 performs track signal transmission only.

5.6.4.3 Direct Inject Track Circuit

For setting-up the AF-902/904 using a track cab loop, follow the procedure in Tables 5-1, 5-2,and 5-6, and use the Data Sheet at the end of this section. Tuning is not required for a directinject circuit.

5.6.4.4 System Reset

Upon power-up or reset, the unit goes through reset, tests RAM, tests PROM, initializes thesystem, reads configuration from EEPROM, checks standby communications to determine itsprimary/standby status, then goes to [MAIN] [MENU]. If the unit has been calibrated, it willthen begin to transmit and operate.

All of the procedures require that the Operator first go to the [CNFG] [MENU] from the[MAIN][MENU] and enter the proper password. Once the password is entered, the unit entersthe [SET] [UP] menu. This initial procedure is detailed in Table 5.1. From there, the track circuitcan be tuned and calibrated, and the MICROLOK II address and track ID can be set.

5.6.4.5 Tuning Test Procedure

NOTE

Words in single [BRACKETS] are exact display output charactersfor the specific step.

A. Set Receiver RXA and RXB, and Transmitter TXA and TXB Taps, to position 3 on the backof the cardfile motherboard.

B. Power-up the primary and backup units.

C. Input the front panel menus as described in the set-up and test procedures.


5-6 SM8051

5.7 AF-902/904 TRACK CIRCUIT SYSTEM SET-UP AND TEST

Table 5-1. Entering The AF902/904 Restricted Menu For Set-Up

Restricted Menu Access Procedure

From [MAIN][MENU] press ENTER

Toggle MODE to [CNFG][MENU]

Press ENTER for [PSWD][MENU]

Press ENTER for [pswd][AAAA]

ADJUST characters and ENTER

Unit enters [RSTR][MENU]

Press ENTER. If pswd is OK, unit goes through Reset and into [SET ][ UP ]

Table 5-2. AF-902/904 MLOK Address and Track Circuit ID Settings

Step Setting the MLOK Address Setting the Track Circuit ID Number

1 Obtain track circuit MLOK address fromhardware drawings.

Obtain track circuit ID from Control Linedrawings.

2

Traverse restricted menu as described inTable 5-1.

[SET ][ UP ]

Press ENTER for [TUNE][MENU]

Traverse restricted menu as described inTable 5-1.

[SET ][ UP ]


3

Toggle MODE to [MLOK][MENU]

Press ENTER for [addr][ xx]

ADJUST addr (1-31)

Press ENTER for [MLOK][MENU]

Press ESCAPE for [SET ][ UP ]

Toggle MODE to [AC- ][CEPT]

Toggle MODE to [ ID ][MENU]

Press ENTER for [tkid][xxxx]

ADJUST tkid (0-4095)

Press ENTER for [ ID ][MENU]

Press ESCAPE for [SET ][ UP ]

Toggle MODE to [AC- ][CEPT]

4

Press ENTER for [CON-][FIRM]

Press ENTER to scroll through allparameter settings.

* Accept by pressing ENTER.

* Reject by pressing ESCAPE.


Press ENTER to scroll through all parametersettings.




5-7 SM8051

Step Setting the MLOK Address Setting the Track Circuit ID Number

5

If all parameters are CONFIRMED, unitwill write set-up parameters to EEPROMand [DONE]

Press ENTER for system reset.

Record track circuit MLOK Addr onTrack Circuit Data Sheet

If all parameters are CONFIRMED, unit willwrite set-up parameters to EEPROM and[DONE]

Press ENTER for system reset.

Record track circuit ID on Track CircuitData Sheet

5.7.1 AF-902/904 350 or 500 MCM Track Circuit Set-Up

For set-up of an AF-900/904 350 or 500 MCM track circuit, proceed with Table 5-3 and 5-4.

Table 5-3. Af-902/904 350 or 500 MCM Tuning Instructions

Step AF-900 Operator Track/Coupling Unit Technician(s)

1Obtain track circuit frequency, (Fc) fromControl Line Drawings.

Set both coupling units to nominalcapacitor setting vs. frequency fromTable A

2

Traverse restricted menu as described in Table5-1 to

[SET ] [ UP ]


Verify that coupling unit JMP9{JMP16} is set to “NORM” position.

3Press ENTER to automatically set direction ofsignal travel(West to East)

Using Fluke Scopemeter 97 in V acmode – Monitor voltage at: TP2 andTP1 {TP5 and TP6}.

4

Press ENTER for [freq][ 0.0]

Toggle AUX to set frequency to Fc-400.

Press ENTER for [pwr ][ xx%]

Set pulsewidth to [pwr ][ 50%]

Unit is now transmitting.

Tune EAST coupling unit.

Vary capacitance with JMP1-JMP8{JMP10-JMP17} to peak voltageacross:

TP2 and TP1 {TP5 and TP6}

5Record final capacitance (W->E) on TrackCircuit Data Sheet.

6 Press ENTER to automatically set direction ofsignal travel (East to West)


5-8 SM8051

Step AF-900 Operator Track/Coupling Unit Technician(s)

7 Press ENTER for [freq][ 0.0]

Toggle AUX to set frequency to Fc-400.


Set pulsewidth to [pwr ][ 50%]


Tune WEST coupling unit.

Vary capacitance with JMP1-JMP8{JMP10-JMP17} to peak voltageacross:

TP2 and TP1 {TP5 and TP6}

8 Record final capacitance (W->E) on TrackCircuit Data Sheet

9 Press ENTER to complete tuning sequence andreturn to [TUNE][MENU]

Table 5-3A Coupling Unit (Nominal Capacitance Setting)

Note: Final tuned settings will be nominal +/- 2.0 µF (micro farads).

Freq.(Fc) 9.5KHz 10.5 11.5 12.5 13.5 14.5 15.5 16.5

NOM. CAP. 20.0 µF 17.33 µF 15.00 µF 13.00 µF 11.00 µF 9.47 µF 8.47 µF 7.33 µF

Table 5-4. AF-902/904 350 or 500 MCM Calibration Procedure

Step AF-902/904 Operator Track/Coupling Unit Technician(s)

1 Obtain track circuit frequency, (Fc)from Control Line Drawings.

2

Traverse restricted menu as describedin Table 5-1 to

[SET ] [ UP ]


Toggle MODE to [CALI][BRAT]

Press ENTER for [freq][xx.x]ADJUST frequency to Fc.

3

Press ENTER to automatically setdirection of signal travel (West to East)




5-9 SM8051


4

Select appropriate transmitter tap andADJUST [pwr ][ xx%] to set Irail forW to E.

(For Irail setting, refer to Table 5-4B orTable 5-4C)

Using the HP3560A in V ac (rms) mode withthe 80i-1000s Current Transformer (x100),attach Probe to Center of 350 or 500 MCMBond and monitor/report rail current (Irail) atEast track bond.

5

Record Irail, transmitter tap and pwr forW->E on Track Circuit Data Sheet.

NOTE: At cross-bonding points, the S-bond isdoubled. The resulting Irail is the sum.

6 Press ENTER to automatically setdirection of signal travel (East to West)

Move to West track bond.

7


ADJUST [pwr ][ xx%] to set Irail for Eto W.

(For Irail setting, refer to Table 5-4B orTable 5-4C)

Using the HP3560A in V ac (rms) mode andthe 80i-1000s Current Transformer (x100),attach Probe to Center of 350 or 500 MCMBond and monitor/report rail current (Irail) atWest track bond.

8 Record Irail and pwr on Track CircuitData Sheet.

9

Press ENTER for [Levl][ xx%]

Set Receiver tap that produces lowestLevl within range of 18% < Levl <77%

Record receiver tap and Levl for E->Won Track Circuit Data Sheet

10

Press ENTER for [Vari][ x%]

Record [Vari][ x%] for E->W

Press ENTER for [Shnt][151 - 171%]

Record [Shnt][151 - 171%] for E->Wwhen unshunted.

< Vari is the MAX variance of < Fm or Fsfrom Fc and should be within 0-7%.

< Shnt displays received level < w.r.t. shuntthreshold.

11Note: When SHUNT applied, checkthat [Shnt][ xx%] < 100%.

Record [Shnt][ xx%] when shunted

Apply 0.2ohms shunt to track at center ofWest Bond.

12 Press ENTER to automatically setdirection of signal travel (West to East)


5-10 SM8051


13

Press ENTER for [Levl][ xx%]

Check that 20% < Levl < 80%

Record [Levl][ xx%]

Press ENTER for [Vari][ x%]

Record [Vari][ x%] for W->E

Press ENTER for [Shnt][151 - 171%]

Record [Shnt][151 - 171%] for W->Ewhen unshunted.

14NOTE: When SHUNT applied, checkthat [Shnt][ xx%] < 100%.

RECORD [Shnt][ xx%] when shunted

Shunt track w/0.2ohms at East Bond.

15

Press ENTER for [AC- ][CEPT]


Press ENTER and scroll through allparameter settings.



Note: During accept mode, parameter valueswill be written to both displays. DO NOTACCEPT if display values differ.

16

If all parameters are CONFIRMED,unit will write set-up parameters toEEPROM and [DONE]. Press RESETbutton for system reset.

After reset, system LEDs should show bybeing lit:CPS ACTIVE, ON-LINE, SELF, MLOKCOMM, LEVEL, DATA

Table 5-4B Rail Current Settings (350 MCM, 500 MCM, and Cab Loop Circuits)

Nominal Irail current +/- 2 mA.

Freq.(Fc) kHz 9.5 kHz 10.5 11.5 12.5 13.5 14.5 15.5 16.5

NOMINALIRAIL (mA)

105 95 87 80 75 70 65 60

Table 5-4C Rail Current Settings (Direct Inject Circuits)

Nominal Irail current +/- 2 mA.

Freq.(Fc) kHz 9.5 kHz 10.5 11.5 12.5 13.5 14.5 15.5 16.5

NOMINALIRAIL (mA)

210 190 175 160 150 140 130 120


5-11 SM8051

For the AF-902, power down the primary unit and repeat the calibration procedure for thebackup unit.

NOTE

Backup unit must have same MLOK Address, TRK ID, Fc,password and Exec. software version as the primary unit.

Table 5-5. AF-902/904 Cab Loop Track Circuit Set-Up


1

Traverse restricted menu asdescribed in Table 5-1 to

[SET ] [ UP ]

Press ENTER for [TUNE][MENU]Toggle MODE to [CALI][BRAT]

Press ENTER for [freq][xx.x]

ADJUST freq. to [freq][16.5]

Note: All cab loops employ a single coupling unitlocated at the transmit end.

The AF902/904 does not receive a signal backfrom the track.

2 Press ENTER for [DIR ][W->E]


Check cab loop wiring to insure properconnections.

AF902/904 signal wire to 1,2 {4,5}

Cab loop wire to 7,8 {10,11}

3

Select appropriate transmitter tapand ADJUST [pwr ][ xx%] to setICabloop to 275mA for Cab loop.

Using the HP3560A in V ac (rms) mode with the80i-1000s Current Transformer (x100), attachprobe to cab loop wire and monitor/report loopcurrent (Iloop) to the Train Control andCommunications Building (TCCB).

4

Record Iloop, transmitter tap andpwr for CAB LOOP on TrackCircuit Data Sheet.

If location is a double crossover, proceed to othercab loop.

5 Press ENTER for [DIR ][E->W]

6

Check cab loop wiring to ensure properconnections.


Cab loop wire to 7,8 {10,11}

7


ADJUST [pwr ][ xx%] to thesame “pwr” value set in step 3.

Check that the ICabloop > 250mA.

Using the HP3560A in V ac (rms) mode with the80i-1000s Current Transformer (x100): AttachProbe to Cab loop wire and monitor/report loopcurrent (Icabloop) to TCCB.


5-12 SM8051


8 Record Icabloop and pwr on CabLoop Circuit Sheet.

(see NOTE ->> )

Note: Connect VOLTREX jumper wires fromauxiliary PCB transmitter outputs to Rec. inputs

9

Press ENTER to scroll throughremaining menus to: [AC-][CEPT]

(Disregard Levl, Vari and Shntreadings, see NOTE ->> )


Press ENTER and scroll through allparameter settings.

* Accept by pressing ENTER

* Reject by pressing ESCAPE

Note: During accept mode, parameter values willbe written to both displays. DO NOT ACCEPT ifdisplay values differ.

10

If all parameters areCONFIRMED, unit will write set-up parameters to EEPROM and[DONE] Press RESET button forsystem reset.

Note: After reset, system LEDs should show bybeing lit:

CPS ACTIVE, ON-LINE, SELF, MLOKCOMM,(LEVEL & DATA off)

Table 5-6. AF-902/904 Direct Inject Track Circuit Set-Up


Proceed step by step with thecalibration procedure in Table 5-4.

Proceed step by step with calibration procedurein Table 5-4.

Exception Notes:

(STEP 4 & STEP 8)

Check coupling unit wiring.


Track Inject wire to 6,8 {9,11}

Irail settings to be done with 0.20 ohm shunt inplace across rail at receive end.

Current transformer on shunt.


5-13 SM8051

5.8 TEST DOCUMENTATION AND DATA SHEETS

The results of the set-up and test procedures must be fully documented, using the approvedcircuit plans and the test data sheets. For specific information concerning a particular location’sAF-902/904 installation, refer to that location’s circuit drawings, book of plans, test recordsheets, and any other installation data that may be available. The type of information that isavailable may vary and is dependent upon the railroad or transit authority’s record keepingpolicy.

The approved circuit test plans are used to record the results of the set-up procedure. A circuitthat has been tuned only should be checked in blue. A circuit that has been both tuned andcalibrated should be checked in green. If corrections to the circuit plans are required as a result ofany procedure, the Test Engineer should document the changes using Yellow=Out and Red=Incolor coding. In addition, the Test Engineer is required to initial and date the changes and tofurther document the changes by using the Standard Discrepancy/Action Item List to fullydescribe the discrepancy and the action taken.

The data sheets provided on the following pages are to be used to record the results of the tests.The top portion of the data sheet should be filled in before beginning the test. As part of this, theTest Engineer should record the track circuit length and the approximate cable length from theTCCB to the nearest coupling unit.


5-14 SM8051

AF-902 Track Circuit Data Sheet

Location __________________________________________________________

Track Circuit Length (100-1000 ft, 30-305 m)_______________Feet/Meters

Cable Length to Nearest Bond (100-1000 ft, 30-305 m)________Feet/Meters

Track Circuit ID# (1-4095)______________ MLOK Address (1-127)__________

Tuning Procedure

Frequency (kHz) 9.5 10.5 11.5 12.5 13.5 14.5 15.5 16.5

Direction West to East East to West

Coupling UnitCapacitance ___________________________µF ___________________________µF

Calibration Procedure

Transmitter TapSetting 1 2 3 4 5


AF-902 Unit Primary Backup Primary Backup

[pwr]Pulse Width(20% - 95%) ____________% ____________% ____________% ____________%ΙRAIL(mA) ___________mA ___________mA ___________mA ___________mA

Receiver TapSetting 1 2 3 4 5

Receiver Level

[Levl]

[Vari]

____________%20-80%

____________%0-7%

____________%20-80%

____________%0-7%

____________%20-80%

____________%0-7%

____________%20-80%

____________%0-7%

Shunt Level

[Shnt]Unshunted

[Shnt] Shunted

____________%151 - 171%

____________%< 100%

____________%151 - 171%

____________%< 100%

____________%151 - 171%

____________%< 100%

____________%151 - 171%

____________%< 100%

Inspector___________________________________________ Date____________________


5-15 SM8051

AF-902 Cab Loop Data Sheet

Location __________________________________________________________

Cable Length to Cab Loop Coupling Unit (100-1000 ft, 30-305 m)_____Ft/m

Track Circuit ID# (1-4095)____________ MLOK Address (1-127)___________


Frequency (kHz) 9.5 10.5 11.5 12.5 13.5 14.5 15.5 16.5



AF-902 Unit Primary Backup Primary Backup

[pwr]Pulse Width(20% - 95%) ____________% ____________% ____________% ____________%ΙCABLOOP(mA)

250mA < I <300mA

___________mA ___________mA ___________mA ___________mA


(Not Applicable)

Inspector___________________________________________ Date____________________


5-16 SM8051

AF-904 Track Circuit Data Sheet

Location __________________________________________________________

Track Circuit Length (100-1000 ft, 30-305 m) _______________Feet/Meters

Cable Length to Nearest Bond (100-1000 ft, 30-305 m)________Feet/Meters

Track Circuit ID# (1-4095)______________ MLOK Address (1-127)__________

Tuning Procedure

Frequency (kHz) 9.5 10.5 11.5 12.5 13.5 14.5 15.5 16.5


Coupling UnitCapacitance ___________________________µF ___________________________µF




[pwr]Pulse Width(20% - 95%) ____________% ____________%ΙRAIL(mA) ___________mA ___________mA


Receiver Level

[Levl]

[Vari]

____________%20-80%

____________%0-7%

____________%20-80%

____________%0-7%

Shunt Level

[Shnt]Unshunted

[Shnt] Shunted

____________%151 - 171%

____________%< 100%

____________%151 - 171%

____________%< 100%

Inspector___________________________________________ Date____________________


5-17 SM8051

AF-904 Cab Loop Data Sheet

Location __________________________________________________________

Cable Length to Cab Loop Coupling Unit (100-1000 ft, 30-305 m)_____Ft/m

Track Circuit ID# (1-4095)____________ MLOK Address (1-127)___________


Frequency (kHz) 9.5 10.5 11.5 12.5 13.5 14.5 15.5 16.5



[pwr]Pulse Width(20% - 95%) ____________% ____________%ΙCABLOOP(mA)

250mA < I <300mA

___________mA ___________mA


(Not Applicable)

Inspector___________________________________________ Date____________________


5-18 SM8051



6-1 SM8051

6 PREVENTIVE MAINTENANCE

6.1 INTRODUCTION

This section describes the maintenance tasks required for the AF-902/904 track circuit unit,coupler and AF-902/904 350 or 500 MCM bond. These preventive maintenance tasks are to beperformed on as-scheduled basis, whereby the components are inspected, cleaned, tested, andadjusted at periodic intervals to ensure the proper operation of the AF-902/904 unit.

6.2 IMPORTANCE OF PREVENTIVE MAINTENANCE

Regular Preventive Maintenance Inspection (PMI) can prevent failures and system malfunctions.

The responsibility of the maintenance personnel is to keep the AF-902/904 unit in safe andsatisfactory operating condition at all times. This is accomplished through regular inspections,cleaning and testing and through required adjustments of the unit. By maintaining up-to-daterepair and PMI records, and reviewing the history of these activities, maintenance schedules canbe set to prevent circuit performance deterioration. PMI can lead to the discovery of questionableconditions before major malfunctions can occur, potentially causing train traffic problems andeventually total train stoppage.

6.3 PREVENTIVE MAINTENANCE TASKS

The following tasks are to be performed on a scheduled basis, as determined by past performanceand reliability records. As in the case of any operational equipment where safety and reliabilityare of prime concern, it is recommended that the minimum PMI interval be no less than every sixmonths. This interval may be reviewed and changed accordingly, based on the equipment'songoing performance.

6.3.1 Equipment Cleaning Procedure

Cleaning is necessary to remove all accumulated dirt and other foreign matter from the AF-902/904 track circuit unit, coupler and track bonds that form the AF-902/904 system. Whilecleaning any of these system components, the Maintainer must exercise the necessary caution inorder not to damage or dislodge any wires or connectors.

6.3.1.1 Cleaning Materials

The following cleaning materials are required to effectively clean the unit and remove unwanteddebris. The cleaning supplies are of commercial grade and may be purchased from any cleaningsupplier.

Item Use

Household Cleaner Mild liquid cleaner used to clean exterior surfaces.

Lint-Free Cloths Used to clean and dry exterior surfaces.


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Soft Bristle Brush Used to remove dust and foreign matter from terminalblocks, electrical connections, and equipment surfaces.

Air in Aerosol Can Used to blow out dust and foreign matter from delicatecomponents and electrical surfaces.

6.3.1.2 Room Equipment Cleaning Procedures

When cleaning the AF-902/904 track circuit cardfile located in the equipment room, safetywarnings should be adhered to and precautions should be taken to prevent personal injury.

WARNING

Hazardous voltages and current may be present. Use extremecaution when working near exposed terminals. Never use wetcloths near exposed electrical terminals.

The following procedures are to be used:

A. Remove dust and dirt from all accessible surfaces using a soft bristle brush.

B. Using compressed air, blow out dust and dirt from inaccessible areas around terminal blocks,fuse holders, and other areas where live electrical conductors are exposed.

CAUTION

When using compressed air to blow out dirt and dust particlesfrom cardfiles, always direct air at an angle relative to the PCBsso that damage will not occur to the mounted components.

C. Wipe exterior and interior surfaces, not exposed to electrical circuitry, with a lint-free clothdampened with a solution of water and household cleaner to remove all dirt and foreignmatter.

D. Dry all surfaces with lint-free cloth.

E. Using compressed air or a soft bristle brush, remove all dust and dirt particles from cardfiles,wiring and other areas that may not be accessible using standard cleaning methods.

6.3.2 Track Circuit Inspection

Track circuit inspection should take place at least once per year or more frequently if desired.

This inspection procedure consists of observing the physical condition of the equipment andperforming any actions or operations that may affect the function of the item under test. It maybe necessary to take appropriate cleaning steps prior to inspection. Knowledgeable maintenancepersonnel who are familiar with the operational functions of the system should inspect for


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appearance, smell, sound and feel of the equipment. Any of these observation methods can alertthe maintenance personnel of fault conditions.

6.3.2.1 AF-902/904 Room Equipment

The following inspection procedures should be used:

A. Check the AF-902/904 front panel to ensure that all PCBs are fully inserted.

B. Verify that all PCBs, primary and backup for all track circuits, are inserted into their properslots.

C. Verify that all PCBs are securely mounted in the guides at the top and bottom.

D. Check that the cable connections to the rear of the cardfile are intact, tight, and free fromnicks, cuts, and fraying.

6.3.2.2 Track Side Components

The following inspection procedures should be used:

A. Check all cable connections from the AF-902/904 unit's auxiliary PCB connectors on the rearpanel to the track circuit coupling units for any signs of nicks, breaks, kinks, corrosion orfraying.

B. Check all cable connections from the AF-902/904 coupling units to the appropriate 350 or500 MCM bond locations for any signs of nicks, breaks, kinks, corrosion or fraying.

C. Verify that the inside of the track coupling unit is free from water and any moisture.

D. Check all 350 or 500 MCM bond connections for damage, corrosion, and tightness.

E. Check that all PVC tubing is properly secured against the 350 or 500 MCM cable.

F. Check all wayside components for any signs of physical damage, such as cracks in loop PVCtubing, etc. Check all mounting hardware for tightness and to see if any of the hardwareneeds to be replaced.

G. Remove any debris or foreign objects that may hinder the proper operation of the AF-902/904track circuit system.

NOTE

If any fault condition is observed during inspection, it should becorrected immediately. Inform your supervisor at once for properprocedures.


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6.4 TRACK CIRCUIT CHECKS

Track circuit PMI testing is performed to ensure that all circuits are working properly. It can beassumed that the circuits are performing their function to some degree since failures have notbeen reported prior to the PMI efforts. It also can be assumed that the circuits are withinoperational tolerance. The track circuit checks are performed to verify how much the circuit is intolerance, or how close is it to failure.

The purpose of the following procedure is the set-up of the AF-902/904 FSK track circuit using a350 or 500 MCM Bond. It contains two main sections, tuning and calibration. The tuning portionmust be performed prior to the calibration procedures. The tuning portion is performed in orderto tune the associated coupling units to the frequency of use. The calibration portion is done toset rail current, shunt detection and sensitivity.

At least two people will be required to perform these procedures: one Operator at the AF-902/904 cardfile and one track coupling unit Technician.

6.4.1 Track Circuit Sensitivity

As part of the calibration portion of the routine, the regularly scheduled PMI will require testingfor track circuit sensitivity. Before this test can be performed, tuning should be performed inorder to tune the two associated coupling units to the desired track circuit frequencies (9.5, 10.5,11.5, 12.5,13.5, 14.5, 15.5, 16.5 kHz). The tuning frequency and track circuit sensitivityinformation can be found on the initial installation track circuit data sheet.


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7 TROUBLESHOOTING

7.1 INTRODUCTION

This section describes the methods and procedures that can be used by qualified Maintainers toidentify, test, isolate and repair faulty conditions in the AF-902/904 track circuit. All repairs willbe to the Lowest Repairable Unit (LRU) that is practical for field maintenance situations.

7.2 APPROACH TO TROUBLESHOOTING

The process of isolating a failed or faulty component(s) is called "troubleshooting." This is acarefully planned approach that will lead to identifying the cause of a system's stoppage orabnormal operation.

The responsibility of the maintenance personnel is to locate the cause of failure and repair thecondition as soon as possible. This can be accomplished only if a systematic approach is takenby qualified personnel who are familiar with the test equipment and testing procedures. Thefollowing basic concepts apply to any troubleshooting situation:

Observe and analyze thesymptom

The symptom may identify the site location, sub-system,hardware vs. software causes, or cable/communications link.

Sectionalize the system If it is difficult to identify the faulty subsystem, theMaintainer should proceed to sectionalize the system inhalves until the site and subsystem are known.

Localize the fault withinthe Subsystem

Identify the LRU and test by using available software orcontrol panel diagnostics.

Isolate the cause Continue troubleshooting the LRU for modular replacementor adjustment.

Repair the failure The trouble can be corrected by adjustment, componentreplacement, or wire repair.

Check repair and operation Verify that the repair has been properly done by checking theoperation of the system for any other fault symptoms andirregularities. Never assume that the first fault found was theonly fault.

The priority of field maintenance personnel is to get the system up and running. This calls forprompt action, fault isolation, and trouble repair. In order to achieve this, the Maintainer may notbe required to troubleshoot beyond the modular component level, commonly referred to as theLRU level. The entire troubleshooting process can be quickened by performing "Go-No Go"replacement checks and repair.

The key to identifying the probable cause of failures is the use of a process of elimination. Thisis a most powerful approach to troubleshooting and fault isolation on any system.


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7.3 TROUBLESHOOTING PROCEDURES

7.3.1 Fault Symptoms

Every abnormal symptom is a result of a cause that has a remedy. The Maintainer mustdetermine how severe the cause (how much damage resulted) and how difficult the repairprocess (quick replacement versus system down-time). The table at the end of this subsectiongives a brief listing of symptoms, probable causes, and suggested remedies. These remedies areto the LRU level to assist in swift repair.

The AF-902/904 FSK track circuit system is designed to notify the Maintainer of most faultsthrough the front panel indicators. Before performing any troubleshooting tests or diagnostics,the Maintainer should first make the following observations:

A. Are the power supply LEDs ON?

B. Are the controller, auxiliary, and supply LEDs NORMAL?

C. Is a backplane connector loose or off?

D. Is there any physical damage anywhere near the track circuit's equipment?

If no obvious faults are observed, the Maintainer should proceed with the standardtroubleshooting techniques.

Symptom Probable Cause Remedy

Broken 350 or 500 MCMbond

Check track bond and cabling.

Bad coupling unit Check input and output cableconnectors to coupling unit.

Defective auxiliary PCB Remove and replace.

Track is unoccupied, but lowor no receive signal.

Conductive debris across track Inspect and remove debris.

Intermittent track occupancyindications

Signal threshold level settingon auxiliary PCB not correct

Adjust or replace.

Check tuning procedure.Speed commands interferefrom track circuit to adjacenttrack circuit

Track carrier frequencies areout of specification limits

Verify coupling unitadjustment.


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Symptom Probable Cause Remedy

Adjacent track circuit ON Turn power OFF of adjacenttrack circuit.

When performing the tuningor calibration procedures, theproper carrier frequencycannot be achieved. Adjusting wrong circuit in

coupling unitCheck for correct TX or RXside of PCB.

Voltage not online (LED OFF)to MICROLOK II

CPS voltage dropped Auxiliary or controller PCBfaulty. Remove and replace.

No 500Hz signal on auxiliaryPCB test point

MCU failed diagnostic Check for false trackoccupancy indications.

HEALTH indicator OFF Primary or backup unit isfaulty

Check LEDs on defectivecircuit and replace defectivemodule.

The MCU is continually running diagnostics on the entire AF-902/904 track circuit system. Anyfailure of these diagnostics will signal the MICROLOK II unit of track occupancy. This willmaintain the track circuit in a safe state, not allowing any train traffic until the system is onceagain operating correctly.

7.3.2 Error Code Observation

CriticalError Code Description

Remedy

9 More than two MICROLOK II re-polls occurredin a single AF-902/904 system cycle (360ms)

Check polling settings forMICROLOK unit. Cannotsend more than 1 message toa given station every cycle(360 msec). To allow formessage delays, minimumtime should be 400 msec.

14 Primary and backup units have configuration datawhich does not match

The track ID, centerfrequency or MICROLOKaddress are not the same forboth units. Checkconfiguration and re-configure units as necessary.


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Remedy

16 The CRC for the EEPROM data is not correct Error with EEPROM(configuration) data. If errorpersists, re-configure unit. Iferror still persists, replace theEEPROM (attached to thecardfile).

17 The system was unsuccessful in trying to savedata to the EEPROM

Error with EEPROM(configuration) data. If errorpersists, re-configure unit. Iferror still persists, replace theEEPROM (attached to thecardfile).

19 Copy 1 of the EEPROM record (in RAM) did notmatch copy 2 of the EEPROM record (in RAM)


20 The EEPROM data has had an unexpectedrevision number


22 Copy 1 (EEPROM) of configuration data does notmatch Copy 2 (EEPROM)


23 Copy 1 (EEPROM) of block speed does notmatch Copy 2 (EEPROM). The block speed isover-written to be zero for both copies

Error with blocking speed inEEPROM (configuration)data. Re-set the blockingspeed. If error persists, re-configure unit. If error stillpersists, replace theEEPROM (attached to thecardfile).


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Remedy

30 Incorrect code was returned by the keyboardencoder

If the error occurs once,ignore it. If this errorpersists, it indicates ahardware failure of the CPUboard. Replace board.

32 Number of accumulated frequency monitor rangeerrors exceeded the limit

Normally associated with afailure of the Controllerboard. Replace board.

33 Frequency monitor for center frequency wasrequested during normal (not configuration mode)operation

Normally associated withattempting to calibrate a unitwith other units inoperational mode. Alladjoining track circuitsshould be turned off whencalibrating a unit.

34 Incorrect gain was detected for a receive channel.Channel number can be read using dump eventsfeature.

This is a test of thecalibration of the trackreceivers. This is often dueto noise from adjoining trackcircuits causing saturation ofthe band pass filter. This cannormally be corrected by re-calibrating the circuit with alower tap setting on the trackreceiver.

35 Rejection level incorrect for low-pass filter.Channel number can be read using dump eventsfeature


36 Rejection level incorrect for band-pass filter.Channel number can be read using dump eventsfeature



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Remedy

37 Vital parallel output monitor read an incorrectstate at the output

This usually indicates noiseon the vital output when theoutput is deenergized. Checkfor, and correct, any externalnoise sources. This error canalso be logged by thestandby unit if fail-overmessages are temporallydisrupted at the same timethat the occupancy changesstate. Can also be associatedwith a failure of theController board. If failurepersists, replace board.

38 Vital parallel output monitor read an inconclusivestate at the output

If this is a single occurrence,it is normally noise related.If this error persists, itindicates a hardware failureof the CPU board. Replaceboard.

39 Test of the vital parallel output control monitorcircuit failed


40 Pulse test of the vital parallel output failed If this is a single occurrence,it is normally noise related.If this error persists, itindicates a hardware failureof the CPU board. Replaceboard.

47 Ramp test of the digital-to-analog converter andanalog-to-digital converter failed



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Remedy

48 Track transmit power amplifier is too high or toolow, possibly due to a CPS failure.

If this is a single occurrence,it is normally noise related.If this error persists, itindicates a hardware failureof the AUX board. Replaceboard. This can also occurwhen an AUX board isreplaced and the unit is notre-configured. Re-configureunit.

49 Malfunction was detected in the power amplifiermonitor circuit

If this is a single occurrence,it is normally noise related.If this error persists, itindicates a hardware failureof the AUX board. Replaceboard. This can also occurwhen an AUX board isreplaced and the unit is notreconfigured. Reconfigureunit.

55 System mode change from standby to off-line oron-line to standby

Normal Operation

56 User requested a change in system mode toconfiguration mode

Normal Operation

65 EPROM error was detected If this is a single occurrence,it is normally noise related.If this error persists, itindicates a hardware failureof the Executive PROM orthe CPU board. Replace theExecutive PROMs or theCPU board.

66 RAM error was detected If this is a single occurrence,it is normally noise related.If this error persists, itindicates a hardware failureof the CPU board. Replaceboard.


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Remedy

68 System cycle did not complete within 360ms This can be caused by noiseon the serial link lines duringthe end-of-cycle processing.Check for, and correct, noiseconditions on the serial link.

69 Elapsed time between two MSEC interrupts wasgreater than 2 ms

Software error.

70 Power-up or front panel reset occurred Normal operation.

71 Processor watchdog timed out with no criticalerror logged

Software error

75 Fixed register in CPU was found to contain anincorrect value

Software error

88 Direction relay failed If this is a single occurrence,it is normally noise related.If this error persists, itindicates a hardware failureof the CPU board or thedirection relays. Replaceboard or cardfile.

89 Direction relay monitor failed If this is a single occurrence,it is normally noise related.If this error persists, itindicates a hardware failureof the CPU board or thedirection relays. Replaceboard or cardfile.

All other critical error codes correspond to internal system errors. Contact Union Switch andSignal for repair information.

7.4 PCB FRONT PANEL INDICATORS AND CONTROLS

7.4.1 AF-902/904 CONTROLLER PCB

This front panel consists of two, four-character alphanumeric scrolling displays, and four up-down SPDT toggle switches that can be used to enter and examine data used in the set-up andoperation of the track circuit. Five LEDs provide additional information. In addition, a frontpanel PC-compatible serial port and a Background Mode Debugging Port are available. Theserial port can be made available to the end user, but the background port is for factory use only.


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Additional detailed information is presented in Section 4.2, which describes the full panelcontrols, indications and functions.

Refer to Figure 7-1, Controller PCB Front Panel, for identification and location of Indicatorsand Test Points.

UP

DOWN

ADJMODE

AUX 1

PRESS TORESET

IN RESETWHEN LIT

ESCAPE

STATUSLEDS 2

1

DIR.

W

E

DEBUGPORT

TRK CKTCTRLR

N123603- 01

DIAGPORT



(FACTORY USE ONLY)




SYSTEM MONITORLEDS


9-PIN PORTFOR



ENTER AUX 2

Figure 7-1 Controller PCB Front Panel


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7.4.2 AF-902/904 Auxiliary PCB

Eight front panel LEDs on the auxiliary PCB indicate the status of various key parameters in areadily interpreted format.

• State of Conditional Power Supply, LED On = CPS On

• Status of unit, LED On = Online, LED Off = Standby

• Health (availability) of this unit, LED On = unit available

• Health (availability) of partner unit, LED On = unit available

• Status of the link to track MICROLOK II system, LED On = communicationestablished

• Special Block Speed Restriction Status, LED On = block speed set

• Track Signal Level, LED On = track clear

• Track Data Signal, LED On = track clear

Eleven maintenance test points are also available on the auxiliary PCB front panel. These testpoints allow for quick checking of system voltages and signal status without removing the PCBfor extender mounting.

Refer to Figure 7-2, Auxiliary PCB Front Panel, for identification and location of Indicators andTest Points.

7.4.3 AF-902/904 Power Supply PCB

The power supply PCB was designed specifically for application in the AF-902/904 track circuitcardfile. It occupies one double-width 6U card slot.

Two separate power switches are located on the front panel. They are locking-lever typeswitches that need to be pulled out in order to toggle. Test points and LED indicators for eachsupply output (6 total) are provided and are accessible through the front panel.

Each Power Amplifier Transformer output is also accessible at the front panel. All test points arefed through appropriate current limiting resistors so as to avoid shorting the outputs. All resistorswill not exceed the 50% rating even when shorted to ground.

A solderside cover is provided to reduce the risk of electrical shock, as there are high voltages(ll0/240V ac) on the PCB.

Refer to Figure 7-3, Power Supply Front Panel, for identification and location of Indicators andTest Points.


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AUXILIARYBOARD

N12360401

CPS ACTIVE

ON- L INE

SELF

PARTNERHEALTH

U- LOK COMM

BLOCK SPEED SET

LEVEL

DATATRACKCLEAR

P1

P2

RECEIVERINPUT

+12V

+5 VVITAL

OUTPUTS

BANDPASS FILTER

ANALOG GROUND

+44V

SYSTEM GROUND

+

-

CPS 50 0Hz

TRANSMITTEROUTPUT

SYSTEM MONITORLEDS

MAINTENANCETEST POINTS

AF-902 / AF-904 AUXILIARYPCB

Figure 7-2 Auxiliary PCB Front Panel


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POWER SUPPLYN12360501

ONOFF

+15V

- 15V

+5V

+15V

- 15V LE

FTP

OW

ER

SU

PP

LY

GND

OFF

0

ON

0

XMFR

+5V

+15V

- 15V

+5V

XMFR

- 15V

RIG

HT

PO

WE

R S

UP

PL

Y+15V

+5V

GND

LOCKINGSUBSYSTEM

POWER SWITCH

AC POWERTEST POINTS

POWERMONITOR

LEDS

DC POWERTEST POINTS

LOCKINGSUBSYSTEM

POWER SWITCH

POWERMONITOR

LEDS

DC POWERTEST POINTS


Figure 7-3 Power Supply Front Panel


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8 CORRECTIVE MAINTENANCE

8.1 INTRODUCTION

This section describes the procedures necessary to access, replace and repair the AF-902/904 track circuit system's components to the LRU level that is practical at fieldmaintenance level.

Corrective Maintenance is an unscheduled process instigated by a system failure orresulting from unsatisfactory preventive maintenance data. After a system fault has beenlocalized by performing the necessary troubleshooting and diagnostic testing, theMaintainer is required to adjust or replace the component. Following the componentadjustment or replacement, the Maintainer is required to perform system repairverification.

8.2 REPLACEMENT REPAIR

The AF-902/904 track circuit system is comprised of three major components. These are:

• AF-902/904 FSK cardfile

• AF-902/904 track coupling unit

• 350 or 500 MCM bond

The suggested repairs at the field level are designed to minimize system downtime andreduce the need for specialized or sophisticated test equipment. The EEPROM is integralto the motherboard and cardfile. Replacing the EEPROM requires the cardfile to bereplaced.

8.2.1 AF-902/904 PCB Replacement

The AF-902/904 cardfile is comprised of electronic PCBs housed in a chassis that iscompatible with a 19" wide AF rack. This equipment is located in the equipment roomand requires a power input of 110/240V ac@50/60 Hz (nominal).

Section 1.3.1.1 describes the physical configuration of the PCBs.

8.2.1.1 Required Tools

The only tool required is a medium-sized, flat-blade screwdriver.

8.2.1.2 Procedure

After having identified the faulty PCB, the following steps are to be used for itsreplacement:


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A. Identify the power supply PCB associated with the track circuit PCB to be replaced.Figure 8-1, Power Supply PCB, identifies the top circuit of the PCB as the backuppower and the bottom circuit as primary power.

Turn OFF the corresponding Locking Subsystem Power Switch.

CAUTION

Turning "OFF' the wrong Power Switch will cause ageneral system failure.

B. Turn the captive thumb screws, located at the top and bottom of the defective PCBmodule, counterclockwise until loose.

C. Grasp the Module Ejectors, located next to the thumb screws at the top and bottom,pull the PCB straight out from the board guides and remove it from the cardfile.

D. Install the replacement PCB in the board guides and slide it in until the PCB engagesthe cardfile connector.

E. Turn the PCB thumb screws clockwise until they are finger-tight and the PCB isfirmly positioned against the cardfile frame.

F. Turn ON the associated Power Switch.

NOTE

When any of the three PCBs is replaced, the calibrationprocedure should be rerun to verify the settings and updatethe threshold calculations.

Power supply PCB replacement requires both of the locking subsystem power switches tobe turned OFF prior to removing the PCB. This is considered a total system failure andan emergency repair.

8.2.2 Coupling Unit Replacement

The PCB is mounted in an aluminum box, which is installed within 15 feet (4.572 m) ofthe rail.

The coupling circuit is mounted on a PCB (9" x 13" x 3/32" (22.86 cm x 32.02 cm x .238cm) thick). This PCB incorporates two identical circuits and two terminal strips forexternal connection of inputs and outputs. This single PCB is used for two track circuits,the local transmit circuit and the receiver circuit for an adjacent track circuit.

This unit could be replaced due to either:

• Circuit failure

• Aluminum box is not water tight.


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8.2.2.1 Tools Required

To remove the PCB, a medium-sized, flat-blade screwdriver is required. Refer toaluminum box, part number X451003-2701, for specific tool requirements.

POWER SUPPLYN123605 01

ONOFF

+15V

- 15V

+5V

+15V

- 15V LE

FTP

OW

ER

SU

PP

LY

GND

OFF

0

ON

0

XMFR

+5V

+15V

- 15V

+5V

XMFR

- 15V

RIG

HT

PO

WE

R S

UPP

LY+15V

+5V

GND

LOCKINGSUBSYSTEM

POWER SWITCH

AC POWERTEST POINTS

POWERMONITOR

LEDS

DC POWERTEST POINTS

LOCKINGSUBSYSTEM

POWER SWITCH

POWERMONITOR

LEDS

DC POWERTEST POINTS


Figure 8-1 Power Supply PCB


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8.2.2.2 Procedures

8.2.2.2.1 PCB Replacement

Refer to PCB Part number N12360x01 for detail information on assembly and circuitdiagrams.

A. Turn OFF track circuit power supply on the AF-902/904 FSK cardfile unit located inthe equipment room.

NOTE

Make sure that the correct power supply PCB circuit isturned OFF.

WARNING

All power is to be turned off to the track circuit couplingunit prior to maintenance or replacement. Hazardousvoltages and current are present when power is on.

B. Open coupling unit box with recommended tool(s).

C. Remove terminal wires, labeled 1 through 4, at terminal blocks TBl and TB2. Recordwire location and color for reinstallation purposes.

D. Remove the three PCB mounting screws located at the corners of the board.

E. Remove the PCB by lifting straight up from the box.

F. Replace defective PCB with new PCB.

G. Reinstall PCB mounting screws.

H. Attach wires to TBl and TB2, according to wire location and color.

I. Perform adjustment and calibration procedures outlined in Section 6.

J. Close and secure aluminum box to ensure water tightness.

8.2.2.2.2 Coupling Box Replacement

Refer to manufacturer's equipment manual for specific tool requirements.

WARNING

All power is to be turned off to the track circuit couplingunit prior to maintenance or replacement. Hazardousvoltages and current are present when power is on.


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A. Detach input and output cables from box connectors. (Two Transmit/Receive cablesand two of the One-Loop cables for the track signal.)

B. Remove aluminum box mounting screws at base if mounted to secured surface.

C. Replace defective coupling unit with operational unit and secure, if required.

D. Reconnect input and output cable wires.

E. Perform Steps A, H and I of Section 8.2.2.2.1.

8.2.3 Bond Replacement

The bond track circuit is very simple, in both material hardware and function. It consistsof a few meters of 350 or 500 MCM heavy conductive cable, typically arranged in an "S"shape between the rails, and connected at end points to the rails.

The cables from the coupling units are single loop wires that induce signals into the Loopand into the rails.

Once these cables are installed and verified as operational, there is very little, if anything,that may require replacement. If any damage occurs to this hardware, it will be necessaryto refer to the site's equipment and cable plans and the manufacturer's equipment manual.

8.3 VERIFICATION OF SYSTEM REPAIR

To ensure that the repairs have been performed correctly and that all replacementmodules are fully functional, a system verification must be performed. This verificationprocedure uses the AF-902/904 track circuit system test.

This specific test is described in Section 6.4 and consists of two procedures, tuning andcalibration.

The AF-902/904 tuning procedure performs the following functions:

A. Enter carrier frequency.

B. Tune both coupling units.

The AF-902/904 calibration procedure carries out the following system functions:

A. Enter Carrier Frequency, Track ID, and MLOK Address.

B. Set Transmitter Tap and Vout in order to set rail current (Irail).

C. Set the Receiver Tap and Shunt/Data Threshold.

D. Verify 0.20 ohm shunt sensitivity.


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NOTE

Depending on the repair or replacement that wasperformed, the tuning procedure may not be required. Thisis performed as a set-up procedure and when track settingversus frequency changes is required.

Replacement of AF-902/904 track circuit PCBs does notwarrant the tuning procedure. The calibration procedureshould, however, be performed to verify the repairs.

The following tables contain a summary of these test procedures. Refer to Section 6 forthe detailed procedures.

AF-902/904 Tuning Summary

Step AF-902/904 Operator Track/Coupling Unit Tech

1 From front panel, set CarrierFrequency

Set both coupling units to nominalcapacitor setting vs. frequency.

2 Set direction (automatic)(Transmit East to West)

Tune West coupling unit usingcapacitor jumpers in coupling unit.

3 Set direction (automatic)(Transmit West to East)

Tune East coupling unit usingcapacitor jumpers in coupling unit.

4 Set direction (automatic)(Transmit East to West) and verifytuning

AF-902/904 Calibration Summary


1 From front panel, set CarrierFrequency, Track ID, MLOKAddress


3 Adjust transmitter taps and Vout toset IRAIL

Monitor and report rail current(IRAIL) at East track bond.


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AF-902/904 Calibration Summary


4 Set direction (automatic)(Transmit East to West)

5 Adjust Vout to set IRAIL for E to W Monitor and report rail current(IRAIL) at West track bond.

6 Monitor received signal and adjustreceiver taps

7 Initiate threshold calculation.Verify threshold value

Shunt track with 0.2 ohms at westtrack bond


9 Initiate threshold calculation.Verify threshold value

Shunt track with 0.2 ohms at easttrack bond


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AF-902 and AF-904

Documents

Transcript of AF-902 and AF-904