Elke Zimoch, 3. October 2011 Found on

Elke Zimoch, 3. October 2011

Found on http://www.semanticmetadata.net/category/comic/

Wir schaffen Wissen – heute für morgen


Paul Scherrer InstitutElke Zimoch

Introduction to EPICS


Acknowledgment

Some slides in this talk came form the„Getting started with EPICS“ lecture series of APS.

My special thanks go toNed Arnold

andJohn Maclean

from the Advanced Photon Source.The original talks can be found on

www.aps.anl.gov/epics/docs/GSWE.php

More people to thank for support:Timo Korhonen, Detlef Vermeulen, Dirk Zimoch


Contents

Morning: Introduction to EPICS Lecture• What is EPICS?• Examples from the EPICS tool box• What are Records?• How to set up an IOC?• Conclusion

Afternoon: Hands-on training• Implementation of a Cooling System (IOC)• Some simple clients (medm)• Some more exercises


What is EPICS?

EPICS is:• A collaboration• A software tool kit• A control system

architecture

EPICS is an abbreviation for:Experimental Physics and Industrial Control System

EPICS:• supports distributed control systems for large research

facilities like accelerators• uses Client/Server and Publish/Subscribe methods• uses the Channel Access (CA) network protocol

EPICS


Who uses EPICS?

Some members of the collaboration (very incomplete!): – ANL (APS Accelerator, APS Beamlines, IPNS), Chicago, USA– LANL, Los Alamos, USA– ORNL (SNS), Oak Ridge, USA– SLAC (SSRL, LCLS), Standford, USA– JLAB (CEBAF), Newport, USA– DESY, Hamburg, Deutschland– BESSY, Berlin, Deutschland– Gemini 8m-Telescope, Hawaii, USA– PSI (SLS, SwissFEL), Villigen, Switzerland– KEK, Tsukuba, Japan– DIAMOND Light Source (Rutherford Appleton Laboratory),

Oxfordshire, England– Australian Synchrotron, Melbourne, Australia– Iter (Test Fusion Power Plant), South France– ESS (European Spallation Source), Lund, Sweden


History

• In 1989 started a collaboration between Los Alamos National Laboratory (GTA) and Argonne National Laboratory (APS)(Jeff Hill, Bob Dalesio & Marty Kraimer)

• More than 150 licenses agreements were signed, before EPICS became Open Source in 2004

• Team work on problems, for example over “Tech Talk” mailing list and webpage:

http://www.aps.anl.gov/epics/• Two collaboration meetings every year (spring and autum)

in turns in America, Asia, and Europa• Collaborative efforts vary

– Assistance in finding bugs– Add manpower: Share tools, schemes, and advice

GTA: Ground Test AcceleratorAPS: Advanced Photon Source


Are there alternatives to EPICS?

System Name:• EPICS• TANGO

• DOOCS• Tine

• PVSS(Cern)

Pro:Bugs are already found

Contra:Complicated to adaptto your problems

Pro:Your problems solvedperfectly

Contra:You are on your own(no one can help)

Pro:Outsource your problems

Contra:Expensive

Collaborations:Used at more than one Lab

Single Site Systems:Developed and used in one Lab

Commercial System


The architecture of EPICS

• For EPICS, client and server refer to their Channel Access role: i.e. Channel Access Client and Channel Access Server

• This standard control system architecture is often called

3 tier architecture or 3 layer model

Network based Client/Server Model (hence the EPICS logo):

EPICSClient

CAClient

CA

ServerCA

ServerCA

Client Layer

Server Layer

Connection Layer


What is Channel Access?

• A protocol how to transfer data over network• A single data unit is called Process Variable• A Process Variable has a unique name, which is used to refer

to the data (Naming convention needed!)• The detailed operation of Channel Access is unimportant for

most programmers (it already works…)• Channel Access is not dependent on a single programming

language (native library in C/C++, Java, and C# available)• The entire set of Process Variables establish a Distributed

Real-time Database of machine status, information and control parameters

Process

Variables

CAS

Process

Variables

CAS

Process

Variables

CAS

Process

Variables

CAS

Process

Variables

CAS

Process

Variables

CAS

Process

Variables

CAS

EPICS Database


Some Details of Channel Access

CA Client

CA Server 1 CA Server 2 CA Server 3

Network

1. Query: Broadcast (UDP)

2. Reply: direct connection (UDP)

3. All further queries and replies work directly (Point-To-Point) (TCP)

Default UDP ports: 5064 and 5065Default TCP ports: 5064 and 5065

Defined in environment variablesNeed to be free in firewall!


Channel Access Commands

Process Variables:

Channel Access Server

S1A:H1:CurrentAO

S1:P1:x

S1:P1:y

S1:G1:vacuum

Channel Access ClientWho has a PV named “S1A:H1:CurrentAO”?

I do.

What is its value?

25.5 AMPS

Change its value to

30.5

“connection request” or “search request”

OK, it is now 30.5

30.5 is too high. It is now set to the maximum value of 27.5.

You are not authorized to change this

value

Notify me when the value changes

It is now 20.5

AMPS

It is now 10.5

AMPS

It is now 0.0023 AMPS

“put” or

“caput”

“get” or

“caget”

“set a monitor”

“post an event”

or

“post a monitor”

“put complete”

or

or

CA Server

CA Client

For all fuctionality see

http://www.aps.anl.gov/epics/docs/ca.php

for EPICS R3.14

Channel Access

Reference Manual


Contents




Examples from the EPICS software tool boxO

utp

ut

Inp

ut

CA Server IOC

Control Room

CA Client CA Client

CA ServerServer Programs:(user programs)

iocCoreRecords

Client Programs:alarmhandler

Striptool, medm,many more …

(user programs)

Cannel Access:(UDP/TCP)

4th Layer

Hardware: maybe

controllers and PLCs


What is an IOC?

• A special CA Server and CA Client(IOCs can “talk” to each other)

• A computer running the “IOC Core” program (at least once)• This computer may be:

- VME based, operating system vxWorks (only possibility for old EPICS Versions up to 3.14) or RTEMS

- PC, operating system Windows, Linux, RTEMS- Apple, operating system OSX- UNIX Workstation, operating system Solaris

• An IOC normally is connected to input and/or output hardware (otherwise called softIOC)

• An IOC runs a record database, which defines what this IOC is doing

IOC means

Input Output Controller

We will come back to

details of EPICS

Records later


Some EPICS Client Programs

(from the EPICS Website – very incomplete, selection is no assessment)• ALH: Alarm Handler • BURT: Backup and Restore Tool • CASR: Host-based Save/Restore • CAU: Channel Access Utility • Channel Archiver (SNS) • CSS and BOY: Control System Studio and Best OPI,Yet• Channel Watcher (SLAC) • EDM: Extensible Display Manager (ORNL) • JoiMint: Java Operator Interface and Management INtegration Toolkit

(DESY) • Knobs: Knob Manager and KnobConfig, an Interface to SunDials • MEDM: Motif Editor und Display Manager • StripTool: Strip-chart Plotting Tool • and many more …

+ Command line tools (caget, caput, …)


Client Program: Command line tools

• Read a PV named <NAME>

caget NAME

• Write a PV named <NAME>

caput NAME value

• Get information about that Record

cainfo NAME

• Start a monitor

camonitor NAME (Cancel with [Ctrl] + [c])

>caget ARIDI-PCT:CURRENTARIDI-PCT:CURRENT 350.56>

>caput ARIDI-PCT:CURRENT 401.5Old: ARIDI-PCT:CURRENT 350.56New: ARIDI-PCT:CURRENT 401.5>

>cainfo ARIDI-PCT:CURRENTARIDI-PCT:CURRENT State: connected Host: sls-cagw-1 Access: read, no write Data type: DBR_DOUBLE Element count: 1>

>camonitor ARIDI-PCT:CURRENTARIDI-PCT:CURRENT 250.542ARIDI-PCT:CURRENT 250.537ARIDI-PCT:CURRENT 250.533ARIDI-PCT:CURRENT 250.525>


Client Program: medm


Client Program: StripTool

time

channelvalues


Client Program: Alarmhandler

• Records have predefined alarm states (SEVR):– NO_ALARM– MINOR– MAJOR– INVALID– not connected

to the client (no Record state)

everything okwarningalert (non controls problem) CA server ok, hardware errorNo server!

Tree structure of Records

Guidance

Panel with moreInformation


Contents




What are Records?

A Record is an object with– a unique name– properties (fields) that contain information (data)

different data types can appear in different fields– the ability to perform actions on that data

XYZ1234

Employee : James Bond

Badge Number: 007

Address : Whitehall, London

Salary : £70070.07

unique name

fields Data


Configured by developer

Make a Record from a Measured Value

VAL SEVR TIME

295,5with a unit mA

17.2.2005 14:21:16

NO_ALARM

with technical limits 0 bis 400

with graphical limits 0 bis 370

with a description „Beam current in SR“

A value with a data type

with a unique name ARIDI-PCT:CURRENT

ai

record (ai, "ARIDI-PCT:CURRENT") {

with a time stamp

Readback from hardware/driver

with a severity (alarm status)

field (EGU, "mA")field (EGUF, "400")field (EGUL, "0")field (HOPR, "370")field (LOPR, "0")field (DESC, "Beam current in SR")field (DTYP, "HY8401")field (INP, "#C3 S0 @")

}


Records and Channel Access Process Variables

• A PV name is comprised of two parts– The record name, and– the name of a field belonging to that record

• For example…

A record name

ARIDI-PCT:CURRENT

A field name

EGU.

A dot to join them

A Process variable name

• No dots allowed in Record names!

• Note that if no field name is given, Channel Access will default to using the VAL field “ARIDI-PCT:CURRENT” is interpreted as “ARIDI-PCT:CURRENT.VAL”

that means:

most record fields

can be accessed

individually


What do Records do?

•Analog in•Analog out•Binary in•Binary out•Calculation•Calculation out•Compression•Data fanout•Event•Fanout•Histogram•Motor•Multi bit binary input•Multi bit binary output •PID control•Pulse counter•Pulse delay•Scan•Select•Sequence•String in•String out•Subarray•Subroutine•Waveform

• Depends on

1. Record Type

2. Field values

• Records are active, they do things– Get data from other records or from

hardware– Perform calculations– Check values are in range and raise

alarms– Put data to other records or to

hardware– Activate or disable other records– Wait for hardware signals (interrupts)

• record do nothing until they are processed

incomplete

list!


Record Processing

• Record processing can be periodic or event driven

• Periodic: Standard scan rates are…– 10, 5, 2, 1, 0.5, 0.2 and 0.1 seconds– Custom scan rates can be configured up to

speeds allowed by operating system and hardware

– No precise timing!• Event driven: Events include

– Hardware interrupts– Request from another record via links– EPICS Events– Channel Access Puts

means:

Trigger Record to do what it

is configured to do.


The Record Reference Manual

• Explains records from the EPICS base release• Explains database concepts, record types, and record fields

• New Version as Wiki:http://www.aps.anl.gov/epics/wiki/index.php/RRM_3-14

• Old Version (R3.13): html: http://www.aps.anl.gov/epics/EpicsDocumentation/AppDevManuals/RecordRef/Recordref-1.html

pdf: http://www.aps.anl.gov/epics/EpicsDocumentation/AppDevManuals/RecordRef/Recordref.pdf

• More Records exist.For example Motor Record (part of synApps package):http://www.aps.anl.gov/bcda/synApps/index.php


Example: Measure a Value

Operator

Value (34 °C)

CA Client: medm

Driver

Device Support

Record Support record … field (SCAN, “.1 second”) field (DTYP, “Hy8401”) field (INP, “#C3 S0 @”) field (VAL, “34”)

every 0.1 seconds the recordasks the driver for a valueand the driver reports back

medm sets a CA monitor

every time the value changesrecord triggers callback

IOC


Contents




IOC Overview: What has to be done?

EPICS base

some functions: dbLoadDatabase dbLoadTemplate iocInit

driver(optional)

seq (snl code)(optional)

your own C-code(optional)

make startup script: st.cmdcall iocCore functions

text file

dbd files:xxxApp.dbd(data base definitions)EPICS Version dependent!additional files for drivers

text files

substitutionfiles template filetemplate file

template file

text files

database files (db)

text files

configureRecords

comes withEPICS baseor drivers

configureswhat theIOC does

iocCore

xxxApp


Steps towards your IOC (1/4)

• What you need before you start– Build tools: gcc, make, tar, gzip– Perl scripting language– Development package of readline– Development packages of X11 and Motif– A text editor (e.g. nedit, kwrite, emacs)

• Browse EPICS home http://aps.anl.gov/epics– Get latest Base– Get Extensions:

Config files 3.14, medm

for EPICS extensions like

medm

the latest is not always best: have a look at techTalk, read

“Known Problems” and “Release Notes”

read “Installation Instructions” (Read Me) as well …

We use

baseR3.14.12-1

today

On MS Windows

you need cygwin

in addition



• Extract Base and Extension packagestar xvfz baseR3.14.12-1.tar.gz

tar xvfz extensionsTop_20070703.tar.gz

tar xvfz medm3_1_5.tar.gz –C extensions/src

• Build Baseexport EPICS_HOST_ARCH=linux-x86

cd base-3.14.12-1

make

export PATH=~/base-3.14.12-1/bin/linux-x86:$PATH

• Test the installationsoftIoc

vxWorks-ppc604win32cygwin-x86



• Build Extensions (here: medm)cd extensions/configure

– Edit the RELEASE filenedit RELEASE• Set correct path to EPICS Base, e.g.

EPICS_BASE=/home/epics/base-3.14.12-1

make

cd ../src/medm3_1_5

make

export PATH=~/extensions/bin/linux-x86:$PATH

• Test the installation

medm

This is something you often have to do

with EPICS components



• Make environment variables permanent– Edit ~/.basrc and add variables:

export EPICS_HOST_ARCH=linux-x86export EPICS_BASE=/home/epics/base-3.14.12-1export EPICS_EXTENSIONS=/home/epics/extensionsexport PATH=$EPICS_BASE/bin/$EPICS_HOST_ARCH:\

$EPICS_EXTENSIONS/bin/$EPICS_HOST_ARCH:$PATH

• EPICS can also be installed centrally (and maybe should)– e.g. /opt/epics/base-3.14.12 and

/opt/epics/extensions– or /usr/local/epics/…


How does an st.cmd file look like (on Linux)?

set environmenton the IOC

load dbd filesand register them

load records

start IOC

configure hardware(depends on driver)

start Application

“trainingIOC” should be meaningful (not exampleIOC or myIOC)

more IOC functions in EPICS Application Developer's Guide:

http://www.aps.anl.gov/epics/base/R3-14/12-docs/AppDevGuide.pdf


How to create a record 1: db file

Record Type Record Name

Driverinformation

periodicRecordprocessing

Records can be created in any editorGraphical creation with VDCT (not used at PSI)


How to create a record 2: substitutions and templates

• What to do if you have more than one instance of a device?

– Multiply the record and change the name works ok

– If you have 20 motors db file gets lengthy– If the device not only needs one record but

more(BPM with at least x, y, and intensity)db file gets even more lengthy and confusing [spell maintenance nightmare]

• Solution provided by EPICS:substitution (with macro definition) and template files


How to create a record 2: substitutions and templates

DEVICE = MTRT1$(DEVICE)-TEMP:READ

MTRT1-TEMP:READ

there is no standard file

extension for substitution and

template files in EPICS!

At PSI:

xxx.subs and yyy.template


IOC System in real … step by step

1. Prepare Application (make EPICS base + driver)2. Write startup script (st.cmd file)3. Write records (db file or substitution + template files)4. Save to boot directory5. Set boot parameters of VME computer6. Reboot

– Load and start operating system (vxWorks)– Load and start st.cmd

• Load dbd files• Configure hardware• Load records• Start IOC (iocInit) and create records

7. Test functionality8. Debug files and go to step 6

IOC Development: configure text files (no code, no make)


Contents




10 really neat Things about EPICS

1. It is free

2. It is Open Source

3. There are lots of users

4. All a client needs to know to access data is a PV name

5. You can pick the best tools out there …

6. … or build your own

7. The boring stuff is already done

8. There is a lot of expertise available close by

9. A good contribution becomes internationally known

10. It does not matter, if you need 10 or 10 million PVs(it is scalable)

11. It is fun (but maybe do not tell this to your management)


Where to learn more?

• EPICS home pagehttp://www.aps.anl.gov/epics/

• Tech Talk: listen (and learn)http://www.aps.anl.gov/epics/tech-talk/index.php

• Getting Started with EPICS lecture serieshttp://www.aps.anl.gov/epics/docs/GSWE.php

• Collaboration Meeting (twice a year)http://www.aps.anl.gov/epics/meetings.php


Contents




Problem:

In the LINAC we have a water chiller that must be turned ON whenever the average temperature of two temperature sensors rises above a set point. The set point is nominally 45 degrees centigrade.

Example: Cooling System

Binary out

MTRT1-LI:COOL-SW

Calculation

MTRT1-LI:CALC

CALC: ( (A+B)/2 ) > C

C: 10

SCAN: 10 second

Analog In

MTTR1-LI:TEMP1

EGU: deg C

VALINP

EGU: deg C

VALINP

INPB

INPA

VAL DOL OUT

T2Sensor

SensorT1

IOC

DatabaseADC

ADC

Binary I/O

ChillerAnalog In

MTRT1-LI:TEMP2


• files prepared in directoryTraining/vxWorks

• Installation directory:/home/ioc/MTEST-VME-T1

• Installation:copy (cp) st.cmd and db filecp st.cmd /home/ioc/MTEST-VME-T1cp COOLER.db /home/ioc/MTEST-VME-T1


medm – say it with Pictures

MTRT1-LI-COOL:TEMP1


IOC System in real … step by step

1. Prepare Application (make EPICS base + driver)2. Write startup script (st.cmd file)3. Write records (db file or substitution + template files)4. Save to boot directory: /home/ioc/<IOC-NAME>5. Set boot parameters of VME computer6. Reboot: type reboot in minicom window

– Load and start operating system– Load and start st.cmd

• Load dbd files• Configure hardware• Load records• Start IOC (iocInit) and create records

7. Test functionality8. Debug files and go to step 6

Elke Zimoch, 3. October 2011 Found on

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