Design Standard DS 43-04

Digital Transformation Group Operational Technology

Design Standard DS 43-04

Profinet and Profibus Network Design and Installation

VERSION 2

REVISION 0 NOVEMBER 2018

Design Standard No. DS 43-04 Profinet and Profibus Network Design and Installation

Uncontrolled if Printed of 74 Ver 2 Rev 0

© Copyright Water Corporation 2018

FOREWORD

SCADA Design Standards are prepared to ensure that the Water Corporation’s staff, consultants and contractors are informed as to the Water Corporation’s design standards and recommended practices. Design standards are intended to promote uniformity so as to simplify design and drafting practice and have as their ultimate objective the provision of safe and functional plant at minimum whole of life cost.

The Water Corporation design standards and recommended practices described in this design standard have evolved over a number of years as a result of design and field experience and these have been investigated and documented.

Deviation, on a particular project, from the design standards and recommended practices may be permitted in special circumstances but only after consultation with and endorsement by the Principal Engineer, SCADA in the Water Corporation’s Operational Technology.

Users are invited to forward submissions for continuous improvement to the Principal SCADA Engineer who will consider these for incorporation into future revisions.

Head of Operational Technology

This document is prepared without the assumption of a duty of care by the Water Corporation. The document is not intended to be nor should it be relied on as a substitute for professional engineering design expertise or any other professional advice.

It is the responsibility of the user to ensure they are using the current version of this document.

© Copyright – Water Corporation: This standard and software is copyright. With the exception of use permitted by the Copyright Act 1968, no part may be reproduced without the written permission of the Water Corporation.




REVISION STATUS

The revision status of this standard is shown section by section below:

REVISION STATUS VER/ REV

DATE PAGES REVISED

REVISION DESCRIPTION (Section, Clause, Sub-Clause)

RVWD. APRV.

0/0 08.08.07 All New Edition, draft release for commenting of chapter 1 – 3.

0/1 30.08.07 Chapter 4 Added Chapter 4, minor changes to remainder

1/0 14.03.08 All General Revision after initial review

LR SE

1/1 22.09.08 Various 1.3: Added DS 80 reference 1.4: Added more definitions 1.9: New section 1.10: New section 2.5: Revised DP cycle time formula 2.6: Reduced max permissible cable length for lower baud rates to 1000m. Amended 500 Kbit/s allowance statement. 2.8: Reworded and amended last paragraph to remove ambiguity regarding termination requirements with repeaters. Amended figure 11 2.9: Reworded section to remove ambiguity. 5.3: New section 6.5: New section 6.6: New section 6.7: New section

FW JGB

2/0 22.03.18 Revised

Chapters: 1.2 1.4 1.6 1.7 1.10 4.2 (old 3.2) 5 and all its subchapters (old chapter 4) 6 and all its subchapters (old chapter 5) New Chapters: 2 7.8 7.9

Draft release of Profinet addition as discussion paper for review meeting

FW JGB

2/0 12/11/18 Final release of Profinet FW JGB




REVISION STATUS VER/ REV

DATE PAGES REVISED

REVISION DESCRIPTION (Section, Clause, Sub-Clause)

RVWD. APRV.

additions




Design Standard DS 43-04 Profinet and Profibus

CONTENTS Section Page

1 Introduction ................................................................................................................................... 8

1.1 Purpose .......................................................................................................................................... 8

1.2 Scope .............................................................................................................................................. 8

1.3 References ..................................................................................................................................... 8

1.4 Definitions ..................................................................................................................................... 9

1.5 Standards .................................................................................................................................... 13

1.6 Guidelines ................................................................................................................................... 13

1.7 Further reference documents .................................................................................................... 13

1.8 Mandatory Requirements ......................................................................................................... 13

1.9 Mandatory Documentation Deliverables ................................................................................. 13

1.10 Mandatory Design and Installation Certification ................................................................... 14

2 Profinet Design ............................................................................................................................ 15

2.1 Topology ...................................................................................................................................... 15 2.1.1 Line Topology (NOT to be used) ................................................................................................. 15 2.1.2 Star Topology ............................................................................................................................... 16 2.1.3 Tree Topology (NOT to be used) ................................................................................................. 16 2.1.4 Media Redundancy Protocol (MRP) Ring Topology (to be used) ............................................... 17

2.2 I/O Devices requirements .......................................................................................................... 18

2.3 Ethernet switches requirements ................................................................................................ 18

2.4 Number of I/O Devices per Network ........................................................................................ 19

2.5 Device Names .............................................................................................................................. 20

2.6 IP addresses ................................................................................................................................ 20

2.7 Update Times .............................................................................................................................. 21

2.8 Network load .............................................................................................................................. 21

2.9 SCADA and OIP connections ................................................................................................... 24

2.10 Number of I/O Controllers per Profinet Network .................................................................. 24

2.11 Inter PLC communication ......................................................................................................... 26

2.12 Siemens S7 H-Systems ............................................................................................................... 26

2.13 Device Certification .................................................................................................................... 28

2.14 Cable and Connector Specification .......................................................................................... 28

2.15 Cable length ................................................................................................................................ 28

2.16 Integration of Profibus PA devices ........................................................................................... 28

2.17 Integration of Profibus DP Slave devices ................................................................................. 29

2.18 Designer Checklist ...................................................................................................................... 31




Profibus DP Design ..................................................................................................................... 32 3

3.1 Topology ...................................................................................................................................... 32 3.1.1 Fibre optic .................................................................................................................................... 32

3.1.1.1 Fibre Optic Linear bus (Line) Topology ...................................................................... 33 3.1.1.2 Fibre Optic (redundant) Ring Topology ....................................................................... 33 3.1.1.3 Fibre Optic Star Topology ............................................................................................ 34

3.1.2 RS 485 (copper) ........................................................................................................................... 34 3.1.2.1 RS 485 Linear bus (Line) Topology ............................................................................. 35 3.1.2.2 RS 485 Tree Topology ................................................................................................. 35

3.2 Number of Devices per RS 485 Segment .................................................................................. 35

3.3 Node Addresses .......................................................................................................................... 36

3.4 Number of Nodes on a Profibus network ................................................................................. 37

3.5 Bus cycle time ............................................................................................................................. 37

3.6 Bus speed & Segment Cable Length ......................................................................................... 38

3.7 Spurlines ..................................................................................................................................... 39

3.8 Termination ................................................................................................................................ 40

3.9 Certification ................................................................................................................................ 42

3.10 Cable specification ..................................................................................................................... 42

Profibus PA Design ..................................................................................................................... 44 4

4.1 Topology ...................................................................................................................................... 44

4.2 DP/PA Link and Coupler selection ........................................................................................... 44

4.3 Number of PA Devices per Segment/Coupler.......................................................................... 48

4.4 Spurlines, Splices and Cable length .......................................................................................... 48

4.5 Segment Current consumption and Voltage Drop calculations ............................................. 49

4.6 Bus cycle time ............................................................................................................................. 50

4.7 Termination ................................................................................................................................ 51

4.8 Device Manager PC ................................................................................................................... 51

4.9 Certification ................................................................................................................................ 52

4.10 Cable specification ..................................................................................................................... 52

4.11 Explosion Safety ......................................................................................................................... 52

Installation ................................................................................................................................... 54 5

5.1 Shield connection ........................................................................................................................ 54

5.2 Cable handling and protection .................................................................................................. 54

5.3 Cable spacing .............................................................................................................................. 55

5.4 Fast connect system .................................................................................................................... 56

5.5 Minimum Profibus DP cable length between devices ............................................................. 56

5.6 DB9 Connectors and Profibus installation cable path ............................................................ 56

PLC and SCADA configuration ................................................................................................ 58 6

6.1 PLC configuration ...................................................................................................................... 58 6.1.1 GSD files ...................................................................................................................................... 58

6.1.1.1 Profibus ......................................................................................................................... 58 6.1.1.2 Profinet ......................................................................................................................... 58




6.1.2 Device Watchdog time (Response monitoring) ........................................................................... 58 6.1.3 DP Master or I/O Controller bus monitoring ............................................................................... 58

6.2 Diagnostics .................................................................................................................................. 59 6.2.1 Profibus Diagnostics .................................................................................................................... 59 6.2.2 Profinet Diagnostics ..................................................................................................................... 60

6.3 Profibus DP Bus parameters ..................................................................................................... 61

Appendix ...................................................................................................................................... 62 7

7.1 List of figures .............................................................................................................................. 62

7.2 List of Tables .............................................................................................................................. 62

7.3 List of Equations ........................................................................................................................ 63

7.4 Explanatory notes for Topology drawing 1 (Profibus with Siemens PA Link/Coupler) ..... 64 7.4.1 Estimated DP cycle time: ............................................................................................................. 65 7.4.2 Estimated PA cycle time: ............................................................................................................. 65 7.4.3 PA current consumption: ............................................................................................................. 65 7.4.4 PA Voltage drop calculation: ....................................................................................................... 66

7.5 Explanatory notes for Topology drawing 2 (Profibus with P&F PA Link/Coupler) ........... 66 7.5.1 Estimated DP cycle time: ............................................................................................................. 67 7.5.2 Estimated PA cycle time: ............................................................................................................. 68 7.5.3 PA current consumption: ............................................................................................................. 68 7.5.4 PA Voltage drop calculation: ....................................................................................................... 68

7.6 Explanatory notes for Topology drawing 3 (Profibus with pure DP network, no PA) ........ 69 7.6.1 Estimated DP cycle time: ............................................................................................................. 69

7.7 Explanatory notes for Topology drawing 4 (pure Profinet) ................................................... 69 7.7.1 Estimated Network load: .............................................................................................................. 71

7.8 Explanatory notes for Topology drawing 5 (Profinet with GSDML file based PA proxy) . 72 7.8.1 Estimated Network load: .............................................................................................................. 73




Introduction 1

1.1 Purpose The Water Corporation has adopted a policy of outsourcing most of the electrical engineering and electrical detail design associated with the procurement of its assets. The resulting assets need to be in accordance with the Corporation’s operational needs and standard practices.

This document sets out design standards and engineering practices which shall be followed in respect to the design and specification of electrical works being acquired by the Corporation.

While this design standard aims to be comprehensive, the Designer shall not assume that it covers all requirements for a particular application.

It is the Water Corporation’s objective that its assets will be designed so that these are fit for purpose, have a minimum long term cost and are safe to operate and maintain. In respect to matters not covered specifically in this standard, the Designer shall aim their designs and specifications at achieving this objective.

1.2 Scope The scope of this standard covers in detail aspects of Profibus and Profinet design, configuration and installation which are particular to the Water Corporation’s requirements for water and wastewater assets.

1.3 References References should be made also to the following associated design standards:

DS 24 Electrical Drafting

DS 40-02 Naming Convention

DS 40-09 Electronic Instrumentation

DS 80 WCX CAD Standard

Approved Equipment List




1.4 Definitions

ARP Address Resolution Protocol, a vendor-neutral protocol to map a Network address ( e.g. IPV4 address) to a physical address (e.g. MAC address)

Conformance Classes Three types of Conformance Classes (CC) exist in Profinet CC-A: Provides basic Profinet functionality such as

• Cyclic I/O • Acyclic Parameter data • Device Diagnostics (Alarms) • Device identification via I&M (Information and Maintenance data) • Topology (Neighbourhood detection via LLDP)

CC-B: Extends CC-A by adding: • Network diagnostics via SNMP • Topology information via MIBS to enable SNMP readout • Integration of Switches as IO-Devices to enable network diagnostics

from the I/O Controller via Profinet • System redundancy (CC-B PA)

CC-B features make it the preferred Conformance Class for Process Automation

CC-C: Extends CC-B by adding hardware based Isochronous Real time mode to it as required for example by Motion control applications. CC-C has no relevance for the Process Control Industry

Designer The person or company engaged by Water Corporation to design the part of the asset relevant to this standard

Diagnostic Repeater Regenerates the Profibus-DP RS485 signal in the same manner as the standard Repeater. Additional functionality allows the monitoring of the copper cable up to 100m from the repeater on legs 2 and 3. Leg 1 in intended to be connected closely to the Master PLC.

Allows monitoring of Profibus-DP copper networks from the HMI.

DP/DP coupler Used to link two separate Profibus-DP networks together to allow data exchange between two Masters (Siemens terminology).

DP Master A DP Master is responsible for handling the bus and is typically the PLC (GE Fanuc, Modicon, Siemens etc.). There has to be at least one DP Master on a Profibus but there may be more than one.

DP Master functionalities:

Class 1 DP master: This is the central component of PROFIBUS DP. A Class 1 DP master exchanges information with the distributed stations in a defined, recurring message cycle.

Class 2 DP master: Devices of this type are programming, configuration and/or operator Panels/PC’s. A Class 2 DP master can for example read inputs & outputs, request diagnostic information and may also facilitate DP Slave configuration.

DP Slave A DP Slave “belongs” to a DP Master. DP Slaves can be remote I/O stations, Control Valves, Flowmeters etc.

DP slave functionalities:




DP-V0 (basic functionality): For configuration, parameterization, cyclic reading of inputs, writing of outputs and reading of diagnosis data.

DP-V1: Acyclical services for the writing and reading of parameters and data records (realised with low priority and parallel to the rapid cyclical user data transfer). DP-V1 is an optional function extensions and compatible with the DPV0 basic functionality.

DP-V2: Support for Slave to Slave Internode communications and clock-synchronization (equidistant Profibus). DP-V2 is an optional function extensions and compatible with the DPV0 and V1 functionality.

DP/PA Link Used as a message buffer between PA couplers and the DP bus to allow operation of the DP network at higher/PA bus independent speeds (Siemens terminology, called “DP/PA Gateway” if P&F is used)

FISCO Fieldbus Intrinsically Safe Concept.

Gap factor Determines how many token cycles the master will do before doing a search for a new master on the bus.

GSD File German acronym for “Geräte Stammdaten Datei”, commonly referred to as “Generic Station Description” file in English. A GSD file is nothing more than a simple text file which contains a description of the functionality of a DP or PA Slave in a standardised form. GSD files for DP or PA Slaves are required for the configuration of the DP Master.

GSDML file A GSD file written in XML (Extensible Markup Language) and used for Profinet I/O Devices

HSA Highest Station Address. The highest permissible Master address within a Profibus-DP network. The default value of 126 shall be used.

I/O Controller Comparable to a Class 1 DP Master in Profibus, the I/O Controller is typically the PLC which is responsible for the I/O Devices configuration and provides them with cyclic output data while receiving (consuming) input data from them.

I/O Device Comparable to a DP Slave in Profibus, the I/O Device is a distributed field device that belongs to a at least one I/O Controller. An I/O Device is the provider of input data and the consumer of output data.

I/O Supervisor Essentially identical to the role of a Class 2 Master in Profibus, I/O Supervisors examples are Programming stations, HMIs and/or Diagnostic PCS. An I/O Supervisor can for example read inputs & outputs, request diagnostic information and may also facilitate I/O Device parameterisation (e.g. Device Name assignment, IP address assignment)

kbit/s Kilo bits per second, unit for Profibus transmission/bus speeds

Max. TSDR Maximum Station Delay Responder Time (in tBits). The maximum time a Slave could need before starting to send a response.

Min. TSDR Minimum Station Delay Responder Time (in tBits). The minimum time a Slave shall wait before starting to send a response. Recommend value is 22 irrespective of bus speed which “calms” the bus without unduly increasing bus cycle time.

MBP Manchester Bus Powered. Physical signal level layer (Layer 1) of Profibus-PA. It uses synchronous Manchester coding on (typically) shielded twisted pair cable which also carries the power for the instrument or device.

MRP Media Redundancy Protocol in accordance with IEC 62439, a vendor-neutral protocol to cater for copper or fibre optic based Ethernet OLM Optical Link Module (Siemens terminology). Converts Profibus-DP from RS485 signal level to fibre optic and vice versa. Used to extend the physical Profibus




network range and/or provide immunity against electrical interference or lightning strikes.

PA Slave A PA Slave “belongs” to a DP Master. PA Slaves are Analogue devices such as Temperature, Pressure, Level, Flowmeters etc. PA Slaves can also receive their power from the PA bus.

PA Coupler Allows connection of a (Manchester Bus Powered) PA network to a (RS 485) DP network. A PA coupler is responsible for the physical signal conversion between the two networks and powering of the PA bus (Siemens terminology, called “PA Segment Coupler” or “PA Power module” if P&F is used). PA couplers that are directly connected to the DP bus require the DP network to run at low speeds (45.45 or 93.75 Kbit/s).

PI Profibus International. Profibus User Organisation responsible for governance of Profibus.

Profibus Process Field Bus. Industrial Fieldbus system in accordance with IEC 61158 Type 1 and 3 (encompasses Profibus-DP and PA).

Profibus-DP Profibus for Decentralised Periphery. DP is synonym for cyclic high speed data exchange between a Master (e.g. PLC) and a number of (distributed) Slaves (e.g. I/O stations, instruments, devices) via RS485 or fibre optic based connections.

Profibus-PA Profibus for Process Automation. PA is essentially a transparent extension of Profibus-DP for the replacement of 4-20mA technology in the process industry. It superimposes Profibus-DP on the MBP physical layer which uses only two wires for instrument/device power supply and Profibus communication.

Retry limit Maximum number of successive attempts that the Master “retries” to get a response from a Slave before declaring the Slave as faulty. A value of 5 is recommended for this to allow the bus to “ride though” short lived interference without causing Slaves dropouts.

RS 485 Physical signal level layer (Layer 1) of Profibus-DP. It uses asynchronous NRZ (non-return to zero) data coding over shielded twisted pair cable.

Repeater Regenerates the Profibus DP RS485 Signal in amplitude and time. Used to extend the overall physical network length or allow additional devices to be connected to the bus. Certain Repeaters also provide electrical isolation between two Profibus DP segments.

tBit A tBit is the time it takes to transmit one bit and commonly used for bus timing calculations. The value of a tBit is: 1/baud rate.

TSlot Slot time. Maximum time (in tBits) the Master waits for the reception of the start of a response message (the first 11 bit long octet of the response message shall be received within this time which starts after the last 11 bit long octet of the request message has been sent). A retry will be initiated if a response message start is not received with this time.

TSet Setup Time (in tBits). The setup time is an additional waiting time which is started before a message is sent.

TQuiet Quiet time (in tBits). The time a sender of a message waits before he switches from send to receive. The default values are 0 to 9 (baud rate dependent), recommend value is 9 irrespective of the baud rate (the earliest a message can be received is after the expiry of Min. Tsdr. A “0” value may lead to “flooding’ of the receive channel with parts of the reflected sent message).

Profinet Process Field Network. Industrial Ethernet based Fieldbus system in accordance with IEC 61158/61784.




LLDP Link Layer Discovery Protocol, a vendor-neutral protocol used by Ethernet devices for advertising their identity, capabilities, and neighbours in local area network rings

Cut-through A method by which a switch does not buffer the message frame completely but instead evaluates it as it arrives. As soon as the Destination address is read from the arriving message frame the switch will start forwarding the message frame to the specific port that can access the addressed Device.

The delay introduced by this method is ~7 microseconds and independent of the message length.

DCP Discovery and Configuration Protocol, part of the Profinet protocol suite and used by the engineering tool and I/O Controller to discover devices, identify device information and configure device settings such as device name and IP address on a Profinet network

DHCP Dynamic Host Configuration Protocol, a standardised protocol that caters for automatic IP address assignment via a DHCP Server.

LAN Local Area Network

VLAN Virtual LAN

QoS Quality of Service, Profinet RT uses QoS to allow prioritisation of Profinet I/O data over other traffic. Profinet RT frames are tagged with a priority code of 6 (second highest) in the IEEE 802.1Q VLAN header that is part of the Profinet Ethernet message.

SNMP Simple Network Management Protocol, a de facto standard for collecting and organising information about devices on an Ethernet Network

MIB Management Information Base, a collection of definitions that define the properties of an object (which is used by SNMP tools).

MRP Media Redundancy Protocol. A data network protocol standardized by the International Electrotechnical Commission as IEC 62439-2. It allows rings of Ethernet switches to overcome any single failure.

Store and forward A method by which a switch stores the message frame completely and places them in a queue. Switches that support QoS then priorities forwarding of the message frame to the specific port that can access the addressed Device.

The delay introduced by this method varies depending on message length and ranges from ~10 microseconds for a 64 Bytes long message frame and up to ~130 microseconds for a 1500 Byte long message frame.

MAC address Media Access Control address, a physical address that is unique to every device, generally assigned by the device manufacturer and coded into the Devices hardware.

PN/DP Proxy A device that allows integration of Profibus DP Slaves into a Profinet Network

PN/PA Proxy A device that allows integration of Profibus PA Devices into a Profinet Network




1.5 Standards IEC 61158: Digital data communications for measurement and control - Fieldbus for use in industrial control systems (Relevant parts: Type 1 and 3) IEC 61784: Profile Set for Continuous and Discrete manufacturing relative to Fieldbus use in industrial control systems (Relevant parts: Profile 3/1, 3/2 and 3/5-3) IEC 1158-2: Profibus PA physical Layer IEC 61000: Installation and mitigation guidelines - Part 5-2 Earthing and cabling IEC 60364: Electrical installations of buildings - Part 5-54: Selection and erection of electrical equipment - Earthing arrangements, protective conductors and protective bonding conductors. IEC 60079 Electrical apparatus for explosive gas atmospheres Part 11 – Intrinsic Safety “I” Part 14 – Electrical installations in hazardous areas (other than mines) Part 27 – Fieldbus Intrinsically Safe Concept (FISCO)

1.6 Guidelines Profibus Assembling Guideline V1.14 (PI order number 8.022) Profibus PA User and Installation Guideline V2.2 (PI order number: 2.092) Profibus Interconnection Technology Guideline V1.4 (PI order number: 2.142) Profibus Commissioning Guideline V1.09 (PI order number: 8.032) Profibus Guidelines part 3, Diagnosis, Alarms and Time stamping (PI order number: 3.522) Profinet Design Guideline V1.14 (PI order number 8.062) Profinet Installation Guideline for Cabling and Assembly V1.0 (PI order number 8.072) Profinet Cabling and Interconnection Technology V4.0 (PI order number 2.252) Profinet Commissioning Guideline V1.36 (PI order number 8.082) Profinet Security Guideline V2.0 (PI order number 7.002) Profinet IO Conformance Classes V1.1 (PI order number 7.042)

1.7 Further reference documents “Industrial Communication with PROFINET” by Manfred Popp (PI order number 4.182f) “The New Rapid Way to PROFIBUS DP” by Manfred Popp “Profibus PA – Instrumentation Technology for the Process Industry” by Ch. Diedrich and Th. Bangermann.

1.8 Mandatory Requirements In general the requirements of this standard are mandatory. No deviation from the requirements of this standard shall be made without the written approval of the Principal SCADA Engineer. Any request for deviation from the requirements of this standard put forward for approval shall still comply with the Standards as listed in section 1.5 and Guidelines a listed in section 1.6.

1.9 Mandatory Documentation Deliverables The Designer shall produce, sign off and submit the topology drawing(s) for each site to the Water Corporation in accordance with requirements of Design Standard DS80 and shall also submit current certificates as per section 3.9.

The topology drawing(s) for the particular project shall be based on the example topology drawings JP05-72-01, 02, 03, 04 and 05 (refer also sections 7.5, 7.6, 7.7, 7.8 and 7.9).

The Designer shall ensure that the level of detail required by the Water Corporation as shown on the example topology drawings is met.




1.10 Mandatory Design and Installation Certification The Designer shall be certified to perform Profinet and Profibus design by completing a Profinet and Profibus training course offered by Profibus International or a course that has been approved by Profibus International. The Design Engineer shall submit a copy of their current certification as proof. Design engineers who are not certified but are involved in Profinet or Profibus design work shall be closely supervised and their work shall be verified by a Profinet and Profibus certified design engineer.

The Installer shall be certified to perform Profinet or Profibus installation by completing the relevant training course offered by Profibus International or a course that has been approved by Profibus International. The Installer shall submit a copy of their current Installation certification as proof. Installers who are not certified but are involved in Profinet or Profibus installation work shall be closely supervised and their work shall be checked by a certified installer.




Profinet Design 2

2.1 Topology Profinet supports a number of different topologies such as Line, Tree, MRP Ring and Star as well as combinations of these.

The overall topology of the Profinet network is to a large extent pre-determined by the physical layout of the Distributed Periphery (DP) within the Plant. There are nonetheless certain topology design decisions to be made and care shall be taken to avoid impractical or inferior topology designs.

The topology design drawing shall include the following information: • Estimated Network Load • Update Times

Note: Either one Update Time value if it is the same for all I/O Devices OR individually specified per device if different update times are used

• Device Names. • IP addresses. • Ethernet Cable length.

2.1.1 Line Topology (NOT to be used) “Line Topology" is a misleading term for Profinet (or Ethernet Networks in general). While it may be used by people to describe the look of Topology it does constitute a cascading of I/O devices via their inbuilt switches as shown in Figure 1 below.

I/ODevice 1

I/ODevice 2

I/ODevice 3

I/ODevice 4

I/ODevice 5

I/ODevice 6

I/ODevice 7

I/OController

Figure 1: Profinet Line Topology example

Points to note:

• The I/O Device’s inbuilt two-port switch is in essence a three-port switch (one internal and two external ports) and the above line topology diagram is better represented as below

Switch 7

I/ODevice 1

I/ODevice 2

I/ODevice 3

I/ODevice 4

I/ODevice 5

I/ODevice 6

I/ODevice 7

I/OController

Switch 6

Switch 5

Switch 4

Switch 3

Switch 2

Switch 1

Figure 2: Profinet Line Topology example detail

• Loss of downstream I/O Devices occurs if an upstream device is powered off. • Loss of downstream I/O Devices occurs if the inbuilt switch of an upstream I/O Device fails.

Design rule:

• In consideration of the above shortcomings, Line Topology shall NOT be used.




2.1.2 Star Topology A Star Topology is created by simply using Network Switches with a number of devices connected to them.

Switch

I/OController

I/ODevice 1

I/O

Device 2

I/O

Device 3

I/O

Device 4

I/O

Device 5

I/O

Device 6

I/O

Device 7

Figure 3: Profinet Star Topology example

Points to note:

• Loss of the Switch means loss of all I/O devices connected to it.

Design rule:

• Star Topology (areas) become a natural part of any Profinet Network once Ethernet Switches are in use.

• Star Topology may also be used by itself for smaller Networks, providing the following applies:

o Only one Ethernet Switch is used. o I/O controller and I/O devices all reside in the same switch room.

2.1.3 Tree Topology (NOT to be used) A combination of Line and Star and/or Multiple Star Topologies becomes a Tree Topology

Switch

Switch

I/OController

I/ODevice 1

I/O

Device 2

I/O

Device 3

I/O

Device 4

I/O

Device 5

I/O

Device 6

I/O

Device 7

Switch

Switch

Figure 4: Profinet Tree Topology example 1 (multiple Star Topologies)




I/OController

Switch

Switch

Switch

I/ODevice 1

I/O

Device 2

I/O

Device 3

I/O

Device 4

I/O

Device 5

I/O

Device 6

I/O

Device 7

Figure 5: Profinet Tree Topology example 2 (Line and Star topology combined)

Design rule:

• Tree Topology shall NOT be used (MRP shall be used instead).

2.1.4 Media Redundancy Protocol (MRP) Ring Topology (to be used) Network availability is increased by closing a Line Topology back to its starting point and thus creating an MRP Ring

I/O

Device 1

I/ODevice 2

I/ODevice 3

I/ODevice 4

I/ODevice 5

I/ODevice 6

I/ODevice 7

MRP ring

I/OController

Figure 6: Profinet I/O Controller/Devices inbuilt switches based MRP Ring Topology example (information only, NOT to be used in the design)

The above topology utilises the inbuilt switch of each device and thus can only tolerate the powering down of one I/O Device at a time.

For this reason, I/O Controller and I/O devices shall NOT be directly integrated into an MRP Ring via their inbuilt Switch.

Dedicated switches shall be used instead as the backbone of the MRP Ring as shown in Figure 7 below.




I/O

Device 1

I/O

Device 2

I/O

Device 3

I/O

Device 4

I/O

Device 5

I/O

Device 6

I/O

Device 7

MRP Ring

Switch

I/OController

SwitchSwitch

Switch

Figure 7: Profinet Switches based MRP Ring Topology example (MRP and Star combined)

Points to note:

• Whereas Profibus requires usage of OLMs to create a ring structure, Profinet MRP rings can be based on Ethernet copper cables or fibre optic cables as well as a mixture of these.

• One switch in the ring acts as the MRP Ring Manager, all others act as MRP Clients. • Ring reconfiguration time (e.g. due to cable break) can take up to 200ms. Therefore the

Watchdog time for ALL I/O Devices shall be set to a minimum of 200ms. • A maximum of 50 Switches are allowed to be part of the ring. • Using switches as the MRP backbone caters for connection of I/O Devices that have only one

physical Profinet port and/or don’t support MRP. Design rules:

• If 2 (two) or more Ethernet Switches are part of the Network, MRP ring topology shall be used. • The MRP ring shall only contain Ethernet Switches.

2.2 I/O Devices requirements Only Conformance Class B compliant I/O Devices shall be used in the Design which ensures they support the following as a minimum:

• Cyclic I/O. • Acyclic Parameter data. • Device Diagnostics (Alarms). • Topology detection via LLDP. • Device identification via I&M (Information and Maintenance data). • Network diagnostics via SNMP. • Topology information via MIBs to enable SNMP readout.

2.3 Ethernet switches requirements Only Conformance Class B compliant Ethernet Switches that additionally fulfil the following shall be used in the Design:

• Managed Switch. • Removable non-volatile storage medium that contains the switch configuration to cater for easy

Switch replacement. • MRP support to cater for Ring Structures. • QoS support to allow prioritisation of Profinet I/O telegrams.




• I/O Device integration via GSDML file to allow integration of switches into the PLC configuration.

2.4 Number of I/O Devices per Network Whereas Profibus has a hard limit of 124 DP Slaves per DP Network, a Profinet Network can - at least theoretically - contain thousands of I/O devices in one Network.

However, I/O Controllers (i.e. the PLC) impose limits on how many I/O Devices are supported. These limits may vary greatly between different PLCs and Table 1 below contains for a few selected PLCs and Gateways (valid as of December 2017 and subject to change for newer CPU versions and/or firmware).

Note: At the time of writing Schneider Electric did not have a Profinet module for the M580 PLC.

Family CPU Supported number of I/O devices

Siemens

S7-1200

Profinet Interface of all CPUs

(as of firmware V3)

16 I/O devices

Siemens

S7-1500

1511-1 PN CPU

Profinet Interface

128 I/O devices

1515-2 PN CPU

Profinet Interface 1

Profinet Interface 2*

256 I/O devices

32 I/O devices

1518-4 PN/DP

Profinet Interface 1

Profinet Interface 2*

512 I/O devices

128 I/O devices

Communication module CM 542-1 128 I/O devices

Prosoft EtherNet/IP to PROFINET Controller Gateway PLX82-EIP-PNC

36 I/O devices

Modbus to PROFINET Controller Gateway PLX82-MBTCP-PNC

36 I/O devices

Softing EtherNet/IP to PROFINET Controller Gateway FG260

8 I/O devices

Table 1: S7 CPU examples for I/O Device capability * These are to be confirmed by Siemens as it is not allowed in TIA Portal

The Designer shall check the limits of the CPU’s Profinet Interface(s) and/or Communication modules and ensure the number of I/O Devices does not exceed 70% of its capacity to cater for future expansion.

I/O Controller limit 70% rule Design Limit

16 I/O Devices 11 I/O Devices








512 I/O Devices 200 I/O Devices (see note below)

Table 2: Profinet I/O devices 70% rule design limit

200 I/O Devices applies as the design limit for a Profinet Network even for I/O controllers that support considerably more. PLCs that require more than 200 I/O Devices will need to comprise two or more Profinet Networks (e.g. via usage of additional Profinet I/O Controller communication modules or a second on-board I/O Controller interface).

NOTE:

Only I/O Devices that are directly connected to the Profinet Network count towards the 70% rule design limit described in Table 2. PN/DP or PN/PA proxies count only as one I/O Device each, irrespective of the number of underlying Profibus DP or PA devices.

However, subject to the chosen PN/DP or PN/PA proxy, the I/O Controller may include underlying DP or PA devices in its overall I/O device count, thus imposing an engineering limit. It is the designer’s responsibility to ascertain the functionality of any PN/DP, PN/PA or other proxies to ensure the design complies with DS43-04 as well as the capabilities of the I/O Controller.

2.5 Device Names Each I/O Device shall be given a device name which shall be stated on the drawings (this is the Profinet equivalent to the Node address as known from Profibus).

Device names shall in general comply with the IEC 61158-6-10 standard. For the purpose of this Design Standard, the following rules shall be adhered to:

• A device name may be a maximum of 240 characters long and may only contain o Lower case Letters. o Numbers. o Hyphen character (“-“). o Period character (“.“).

• A device name shall start and end with a letter or number. • A device name shall not have the form n.n.n.n (n = 0...999). • A device name shall not start with the character string “port-xyz-“ (x,y,z = 0...9). • Inside a device name, a string of characters between two periods forms a label which may not

exceed 63 characters. • A label shall start and end with a letter or number.

Design Standard DS40-02 Naming Convention should be consulted for further detail.

2.6 IP addresses IP addresses shall be allocated by Digital Services BU by means of an LTM/PTM request submitted to the Design Manager or Project Manager by the Designer

I/O Controller (PLC) and each I/O device shall have an IP address which shall be stated on the drawings.

Note that CPUs with multiple onboard Profinet Interfaces require to have its own IP address range for each onboard Profinet Interface, for example (255.255.255.0 assumed as the Subnet mask):

• 192.168.0.0 to 192.168.0.255 for the first onboard Interface. • 192.168.1.0 to 192.168.1.255 for the second onboard Interface.

While usage of additional Profinet I/O controller cards in the CPU rack may allow re-using the same IP address range, this shall be avoided.

Design rule:




• Each Profinet network shall have its own IP address range.

2.7 Update Times Unlike Profibus, each Profinet I/O Device can have its own update time.

Profinet RT I/O update times can be set in multiples of 2 with 1 ms being the fastest.

Note that Update Times have a direct impact on Network load, Table 3 below contains a list of recommended update times based on number of devices.

I/O update times (ms)

Notes

1 NOT to be used unless specific process requirements exist that require it




16 Recommended for all Networks 32 Avoid unless required to keep Network load down

64 Avoid unless required to keep Network load down May also be used for wireless I/O devices

128 To be used for managed Ethernet switches (their I/O is purely for diagnostics purposes and NOT time critical). May be used for wireless I/O devices

256 Avoid May be used for wireless I/O devices if 128ms is too fast for them

512 NOT to be used Table 3: Profinet update times selection table

2.8 Network load Due to the switched nature of the Profinet Network, Network load varies across different parts of the Network and also depends on the topology. The I/O Controller will in general though experience the highest Network load of Profinet RT I/O traffic.

Two examples below show the effect topology has on network loading per individual port to port connection, values used for these examples are:

• Update time: 1ms for all I/O devices

• I/O Device:

I/ODevice 1

I/ODevice 2

I/ODevice 3

I/ODevice 4

I/ODevice 5

I/ODevice 6

I/ODevice 7

I/OController

0.7%1.4%2.1%2.8%3.5%4.2%4.9%

Card Type Bytes I/O Bytes Totals 32 Digital Inputs 4

24 32 Digital Inputs 4 8 Analogue Inputs 16 32 Digital Outputs 4

24 32 Digital Outputs 4 8 Analogue Outputs 16




Figure 8: Line Topology Network Load example (1ms update time, 24 Bytes Inputs and Outputs per I/O device)

Switch

I/OController

I/ODevice 1

I/O

Device 2

I/O

Device 3

I/O

Device 4

I/O

Device 5

I/O

Device 6

I/O

Device 7

0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7%

4.9%

Figure 9: Star Topology Network Load example (1ms update time, 24 Bytes Inputs and Outputs per I/O device)

Table 4 below contains an overview of Network Load results in relation to number of I/O Devices and Update time (each I/O Device comprising of 24 Bytes of Inputs and 24 Bytes of Outputs).

Green highlighted cells indicate the Network load for the recommended 16ms Update times.

Update Time (ms)

Network Load (%) 25 Devices

50 Devices

100 Devices

150 Devices

200 Devices

250 Devices

1 17.6 35.2 70.4 105.6 140.8 176.0 2 8.8 17.6 35.2 52.8 70.4 88.0 4 4.4 8.8 17.6 26.4 35.2 44.0 8 2.2 4.4 8.8 13.2 17.6 22.0 16 1.1 2.2 4.4 6.6 8.8 11.0 32 0.55 1.1 2.2 3.3 4.4 5.5

Table 4: Network Load examples (24 Bytes of Inputs and 24 Bytes of Outputs per I/O Device)

The expected Network load shall be calculated.

PI’s Network load calculation Excel sheet shall be used for this purpose with an averaged I/O amount per Device to perform a simplified Network load calculation.

While the calculation Excel sheet contains instructions on how to use it, the following applies for the purpose of a standardised rule of thumb calculation:




Figure 10: Network load calculation tool usage example

1.) Minimum transmit clock: Always use 1 ms 2.) Number of devices: Count of all I/O Devices on the Network, excluding Switches 3.) Number of modules: Set to 3 for Input and Output 4.) Net data per device: Input: Roundup (Sum of all Input Bytes/Number of device) Output: Roundup (Sum of all Output Bytes/Number of devices). 5.) Update time per device group: Set to the recommend 16ms for Input and Output (unless other update times are required or desired). 6.) Common Network load: Result of calculation, value is displayed in Mbit/s which is equal to % as Profinet operates on a 100Mbit/s Network. Full duplex operation means the higher of the two values is the worst one. Other Notes:

• Ignore “drives” Group 4 to 6 and include Drives in the general “Remote I/O” Goup 1 • Group 2 and Group 3 only need to be used if Devices with different update times are on the

Network. Design rules:

• Profinet RT I/O traffic shall be kept below 25% (25MBits/s) • Total Network load shall not exceed 50% (50MBits/s)




2.9 SCADA and OIP connections SCADA system shall be connected to the PLC via a separate Ethernet Network and shall NOT be connected to the Profinet Network.

Connection to the PLC can either be done via a dedicated Ethernet card in the PLC rack or via a second on-board CPU Ethernet interface that is NOT part of a Profinet Network.

OIPS may be connected directly to the Profinet Network providing the following applies:

• they communicate directly with the control system (i.e. they are NOT SCADA Clients) and • they are located in the field without easy access to the SCADA Ethernet Network

I/O

I/O

MRP Fibre Optic Ring

Switch

I/OController

Switch

ETH

SCADA Ethernet Network

SCADA

OIP

SCADA

I/O

I/O

I/O

I/O

Switch

I/O

I/O

I/O

Switch

I/O

I/O

Figure 11: Example SCADA and OIP connection

2.10 Number of I/O Controllers per Profinet Network Designers may be tempted to design one large fibre optic MRP ring and have multiple I/O Controllers and all I/O Devices connected to one Profinet Network as per example Figure 12 below.




I/O

I/O


Switch

I/OController

Switch

ETH


SCADA

OIP

SCADA

I/O

I/O

I/O

I/O

Switch

I/O

I/O

I/O

Switch

I/O

I/O

I/OController

ETH

I/O

I/O

I/O

I/O

Switch

Switch

Figure 12: NOT allowed - multiple PLCs on one Profinet Network

While the above will technically work, it creates the following issues:

• Creation of larger than required Profinet Networks. • Network load not easily estimated and requires usage of specialised tools (e.g. SINETPLAN). • All Devices share the same IP address space. • Assignments of which I/O Device belongs to what I/O Controller is no longer easily ascertained

from the schematics. • I/O devices belonging to different I/O Controllers may end up being connected to the same

switch, a switch failure (or wilful isolation of an area) now leads to two or more I/O Controllers losing I/O devices.

Design rule:

In consideration of the above shortcomings, there shall be no more than 1 (one) Profinet I/O Controller connected to a Profinet Network.




Switch

I/O

I/O


Switch

I/OController

Switch

ETH


SCADA

OIP

SCADA

I/O

I/O

I/O

I/O

Switch

I/O

I/O

I/O

Switch

I/O

I/O

I/OController

ETH

I/O

I/O

I/O

I/O

Figure 13: Allowed - each PLC with its own Profinet Network

2.11 Inter PLC communication PLC to PLC communication can be achieved via the common SCADA Network or via PN/PN couplers.

2.12 Siemens S7 H-Systems Should the design call for redundant CPUs in the form of a Siemens S7-400 H System, the following additional requirements shall apply (Note: the S7-400H is due to be replaced by the CPU1513R, CPU1515R and CPU1517H late in 2018):

• MRP is NOT to be used as the main backbone.

S7-400 H systems employ either “Open Ring” Topology OR redundant Profinet Networks instead.

• If “Open Ring” Topology is used, I/O Devices shall support System redundancy (also referred to as “S2” in Siemens speak). This allows the I/O Device to maintain an Application and Communication relationship with both CPUs and carry out a bump-less switch over from one CPU to the other in case of CPU failures.




FO sync. link

I/O

I/O

“Open Ring”

CPU “A”

Switch

I/O

I/O

I/O

I/O

Switch

I/O

I/O

I/O

Switch

I/O

I/O

CPU “B”

I/O

EACH I/O device MUST support System redundancy

Figure 14: S7-400 H System "Open Ring" Profinet Network example

• If redundant Profinet Networks are used to further increase the availability of the Network, I/O devices shall be equipped with redundant Interfaces (also referred to as “R1” in Siemens speak).

FO sync. linkCPU “A”

CPU “B”

I/O

Switch

Switch

I/O

I/O

I/O

I/O device with redundant Interface




Figure 15: S7-400 H System with redundant Profinet Networks example

The connection of I/O devices without redundant Interface to a redundant Profinet Network is possible via usage of so called “Y Switches”.

Note that the I/O Device shall still support System redundancy.




FO sync. linkCPU “A”

CPU “B”

I/O

Switch

Switch

I/O

I/O

Y

I/O




I/O device without redundant Interface(MUST support System redundancy)

Y Switch Figure 16 S7-400 H System with redundant Profinet Networks with “Y” switch

2.13 Device Certification Device certification is mandatory for all Profinet I/O Devices and I/O Controllers thus ensuring that only certified devices are being used.

2.14 Cable and Connector Specification Shielded CAT5 cable shall be used as the minimum standard (i.e. Industrial Ethernet cable). Shielded CAT5e or CAT6 cable may also be used. Only shielded RJ45 connectors shall be used. Fast Connect cable and connectors shall be used (refer 5.4).

2.15 Cable length The design cable length of copper based Ethernet cables shall not exceed 80 meters. Copper based Ethernet cable length shall be shown on the drawings.

2.16 Integration of Profibus PA devices Integration of Profibus PA devices take place via PN/PA proxies who cater for the transition from Profinet to Profibus PA as per example in Figure 16 below




PN/PAProxy

Switch

I/OController

I/ODevice

I/O

Device

I/O

Device

I/O

Device

I/O

Device

I/O

Device

PASlave

PASlave

PASlave

PASlave

T JunctionBox

PASlave

PASlave

PASlave

PASlave

JunctionBox T

Figure 17: PN/PA Proxy usage example

Points to note:

• Capabilities of PN/PA Proxies vary greatly between manufacturers. It is the Designer’s responsibility to check the PN/PA Proxy’s datasheet to ensure the limitations are adhered to and the required spare capacity exists.

• PN/PA Proxy manufacturers generally cater for vendor neutral GSDML file based integration of the Proxy.

• Siemens “SIMATIC CFU PA” (6ES7655-5PX11-0XX0) can only be used with S7 PLCs as the I/O Controller (S7-300, S7-400 and S7-1500).

2.17 Integration of Profibus DP Slave devices Usage of Profibus DP Slaves is to be avoided unless:

• A Device that is mandated to be used is not available with a Profinet I/O Device interface • It is for a brown-field site PLC upgrade where existing Profibus DP Slave devices need to be

integrated If integration of DP Slaves is required, PN/DP Proxies are employed for the transition from Profinet to Profibus DP as per example in Figure 17 below:




(PN/DPProxy)

Switch

I/OController

DPSlave

DPSlave

DPSlave

DPSlave AT

T

I/ODevice

I/O

Device

I/O

Device

I/O

Device

I/O

Device

I/O

Device

Figure 18: PN/DP Proxy usage example

Points to note:

• PN/DP Proxy manufacturers generally cater for vendor neutral GSDML file based integration of the Proxy.

• Siemens PN/DP proxy (part number 6GK1411-5AB10) can only be used with Siemens S7 PLCs as the I/O Controller (S7-300, S7-400 and S7-1500).

• It is the Designer’s responsibility to check the PN/DP Proxy’s datasheet to ensure the limitations are adhered to and required spare capacity exists.

Key differences between Siemens and GSDML file based PN/DP proxies are listed in Table 5 below.

Manufacturer/ Type

Siemens “IE/PB LINK PN IO” (6GK1411-5AB10) GSDML file based PN/DP Proxy

Proxy functionality

Semi-transparent Each DP Slave counts towards the number of configured I/O devices.

Not transparent Proxy counts as one I/O Device irrespective of the number of underlying DP Slaves. Underlying DP Slaves are presented as I/O modules inside the Proxy.

Can be used with any I/O Controller?

No (only useable with Siemens S7 PLCs) Yes

Number of DP Slaves behind one Proxy 65 Depends on chosen Proxy, check

datasheet

Amount of I/O per Proxy 2048 Bytes

Depends on chosen Proxy, check datasheet (but never more than 1440 Bytes)

Other Easy integration into Siemens S7 based control systems

Profinet GSDML I/O device file shall be created via proxy manufacturer supplied engineering tool

Table 5: PN/DP Proxies differences




2.18 Designer Checklist The following checklist shall be used to ensure that the Profinet design meets the requirements of this standard. The answer shall be “Yes” to all the questions.

Chapter Criteria YES?

2.1.1 Line Topology is NOT used?

2.1.3 Tree Topology is NOT used?

2.1.4 MRP backbone is used if more than 1 (one) Switch is in the Network?

2.1.4 If MRP is used, only Ethernet switches are part of the ring?

2.2 Only Conformance Class B compliant I/O Devices are used?

2.3 Only compliant Ethernet Switches are used?

2.4 Number of I/O Devices per Network does not exceed the 70% rule?

2.4 Number of I/O Devices per Network does not exceed 200?

2.5 Drawings show Device Names?

2.6 Drawings show Devices IP addresses?

2.6 Each Profinet Network has its own IP address range?

2.7 Drawings stipulate the Update Times?

2.8 Estimated Network Load is <=25%?

2.8 Estimated Network Load is shown on drawings?

2.9 SCADA is connected separately to the Profinet Network?

2.10 Only one I/O Controller per Network?

2.15 Ethernet copper cable runs are <=80 meters?

2.15 Ethernet copper cable run lengths are shown on drawings?




Profibus DP Design 3

3.1 Topology Profibus DP does generally support a number of different topologies such as (linear) bus, tree, (redundant) ring and star as well as combinations of these.

The overall topology of the Profibus network is to a certain extent pre-determined by the physical layout of the distributed periphery within the Plant. There are nonetheless certain topology design decisions to be made and care shall be taken to avoid impractical or inferior topology designs.

The topology design drawing shall include the following information:

- Estimated cable length for each cable run. - Bus speed. - Termination requirements. - Node addresses. - Estimated DP cycle time.

The copper segments of a Profibus-DP network shall be a linear, multi-drop network.

Copper Profibus-DP sections shall obey the same rules as the RS-485 system on which it is based.

3.1.1 Fibre optic Fibre Optic cabling may be required for certain parts of overall Profibus network for example due to requirements for extended outdoor cable runs (see DS 43-06 for more on this).

Permissible Fibre Optic topologies are:

- Linear bus (also known as “Line”). - (Redundant) ring. - Star.

The following shall be noted and considered when designing the fibre optic topology:

- Preference should be given to using the redundant ring topology in cases where two or more fibre runs are involved (i.e. three or more OLMs are linked together via fibre optic cable). The advantages that ring redundancy offers outweigh the extra costs for the extra fibre run required to convert from line to ring. An exception to this rule is where a number of OLMs are used in line to be able to span greater distances.

- The three possible fibre optic topologies should be treated as mutually exclusive and should not be “mixed and matched” within one Profibus network unless specific reason exists in which case the matter shall be referred to the Principal SCADA Engineer.

- The maximum bridgeable distances between two OLMs is an ideal maximum and only valid for uncut lines without any optical couplings. An optical power budget calculation should be done to calculate and verify the system reserve for any fibre runs which exceed half of the maximum bridgeable distances between two OLMs.

o Example: Siemens Glass multimode OLM (e.g. type G11 or G12) allow for up to 3 kmS between two OLMs. An optical power budget calculation is only required with these OLMs for fibre cable length of more than 1.5 km between two OLMs.




- Each OLM causes a slight delay (~ 6 tBit) in the transmission of the Profibus message due to the required signal conversion. This may need to be taken into account when calculating the bus parameters unless the configuration software allows for inclusion of the number of OLMs and fibre cable length in its calculation.

3.1.1.1 Fibre Optic Linear bus (Line) Topology

OLM

DPSlave

DPSlave

DPMaster

DPSlave

DPSlave

DPSlave

Fibre Optic Line

RS 485

Fibre Optic

OLM

DPSlave

OLM

Figure 19 Example Fibre Optic Line Topology (Note: RS485 Termination requirements not shown)

Points to note:

- None

3.1.1.2 Fibre Optic (redundant) Ring Topology

(redundant) Fibre Optic Ring

DPSlave

DPSlave

DPSlave

DPSlave

DPSlave

RS 485

Fibre Optic

OLM OLMOLM

DPMaster

DPSlave

DPSlave

OLM

Figure 20 Example Fibre Optic Ring Topology (Note: RS485 Termination requirements not shown)

Points to note:

- Due to the OLM inbuilt automatic monitoring functionality and self healing nature of the ring, the Profibus bus timings and setup (i.e. Highest station address, Slot time, Min TSDR and Retry value) shall be adjusted in accordance with the OLM manual (Note: Some Profibus configuration software packages have OLM/fibre based topologies configuration included and are able to automatically calculate and adjust the bus parameters accordingly).




3.1.1.3 Fibre Optic Star Topology

DPSlave

DPSlave

OLM

OLM OLM

OLM

OLMOLM

DPSlave

DPSlave

DPMaster

DPSlave

DPSlave

DPSlave

RS 485 Star Segment!

RS 485

Fibre OpticOLM OLM OLM

Fibre Optic “Star”

Figure 21 Example Fibre Optic Star Topology (Note: RS485 Termination requirements not shown)

Points to note:

- The OLMs are linked together via their RS485 ports to create a (hub like) Star coupler. The small but important RS485 star segment now becomes the main backbone of the whole Profibus network (whereas the fibre is the backbone of the Profibus network in a redundant ring configuration)!

- The RS485 Star segment shall be carefully wired and kept as short as possible (NOTE: The rule of a minimum of 1 meter cable between two adjacent devices shall still be complied with).

- Connection of any other bus participants (e.g. Masters, Slaves) to the RS485 Star segment should be avoided altogether.

- Segment monitoring of the RS 485 channel should be turned off on each of the Star coupler OLMs to keep up a high availability of the RS485 Star segment and therefore of the whole network.

For these reasons, Fibre Optic Star Topologies should be avoided altogether unless specific design criteria exist in which case the matter shall be referred to the Principal SCADA Engineer.

3.1.2 RS 485 (copper) Permissible RS 485 topologies are:

- Linear bus (Line). - Tree.

The following shall be noted and considered when designing the RS 485 bus segments:

- Number of devices per RS 485 Segment. - RS 485 Segment cable length/desired Bus speed. - Termination. - Minimum of 1 meter cable between nodes.




3.1.2.1 RS 485 Linear bus (Line) Topology DP

SlaveDP

SlaveDP

SlaveDP

Slave AT

AT Active Terminating Resistor

T Termination activated on Device or Plug

ATDP

Master

Figure 22: Example RS 485 Line Topology

Points to note:

- None

3.1.2.2 RS 485 Tree Topology DP

SlaveDP

SlaveDP

SlaveDP

Slave AT



Repeater

DPSlave

AT DPSlave

DPSlave

DPSlave

AT

T

Repeater AT

ATDP

Master

Figure 23: Example RS 485 Tree Topology

Note: The cascading depth of repeaters (i.e. permissible number of repeaters downstream of each other) is limited and depends on the type of repeater (e.g. 9 in case of Siemens repeaters).

3.2 Number of Devices per RS 485 Segment It is generally permissible to connect up 32 devices to a single RS 485 segment. In practice this should be avoided though as it leaves no “space” for the temporary connection of diagnostics or troubleshooting tools to the segment. Furthermore, any additional devices required to be added in the future half way though the segment would require additional repeaters somewhere in the field or a redesign of the segment.

The 20% spare capacity rule is to be applied to the number of devices per RS 485 segment and no more than 26 devices shall be foreseen per Segment in the original design.

For ease of troubleshooting and maintenance related tasks, only “Piggyback” Profibus Plug shall be used for devices with a DB9 Plug connection.

In principal all devices which do have an RS 485 interface (driver chip set) shall be counted as a “device” irrespective if they have node address and participate in the bus communication or not.

The following is a list of Profibus items that shall be included in the device count on the RS 485 segment:

- DP Masters (e.g. PLCs, PCs). - DP Slaves (e.g. I/O stations, Valves, Instruments).




- Diagnostic tools (e.g. Profitrace). - Repeaters (incl. Diagnostic Repeaters). - OLMs. - DP/DP couplers. - DP/PA links. - DP/PA couplers (Only if directly connected to the DP bus, not if located behind a DP/PA link) - Surge Arrestors (even though they are passive devices without an RS 485 driver chip interface,

their capacitive mismatch influences the signal quality).

Profibus items which do NOT count as a “device”:

- Active terminating resistors - Profibus Plugs on a device (irrespective if termination is activated on them or not)

3.3 Node Addresses The following Node address assignment rules apply:

Address Device

0 Not to be used (reserved for the connection of temporary Class 2 master diagnostic tools)

1 Main DP Master (Main PLC)

2…n Additional Masters

(i.e. other DP Master PLCs, HMI stations, permanently installed Device Manager PCS or Class 2 Master Diagnostic stations etc.)

n…125

(nminimum = 10)

DP Slaves

(Note: Use 10 as the minimum address)

Table 6: DP Node address assignment

DP Slave address numbers shall - where possible - be assigned with consideration to their associated Plant area.

Example Node Address assignment for a Water treatment Plant with 8 Filters:

Each Filter has 6 associated Profibus DP Slaves associated with it (e.g. one general I/O Station, one Flow meter with DP interface and 4 Valves with DP interface).

Similarly to the Instrument number reflecting the associated Filter number, the DP Slave addresses may, as an example, be logically allocated as follows:




Address Device

0 Free

1 Main PLC

2…n Reserved

10-15 Filter 1 Slaves (16-19 reserved for Filter 1)




50-55 Filter 5 Slaves(56-59 reserved for Filter 5)




90-109 Not used (deliberately kept free for future Filters)

110-125 Remaining other Plant general Profibus DP Slaves

Table 7 DP Slave Addresses

3.4 Number of Nodes on a Profibus network A distinction is made between the total number of Nodes on the Profibus network versus the number of devices per individual RS 485 segment.

Every device that participates in the communication and does have a Node address (i.e. Masters and Slaves) is to be taken into account for this.

The following is a list of Profibus devices that require a Profibus address and shall be included in the Node count on the network:

- DP Masters (e.g. PLCs, PCs) - DP Slaves (e.g. I/O stations, Valves, Instruments) - Diagnostic Repeaters - DP/DP couplers - DP/PA links

A single Profibus network is in principle capable of containing a total of 126 Nodes (Address range 0 to 125) across several RS 485 segments. Since address 0 is not to be used, a maximum of 124 DP Slaves could in theory be connected to the Master port of the PLC (and if the PLC has more DP-Master ports, each is again capable of containing another 124 Nodes).

Designs with more than 80 DP-Slaves on a single Profibus Network are be avoided in order to keep the bus cycle time at an acceptable level (see 3.5 below for more on this).

3.5 Bus cycle time To determine the feasibility of the Profibus Network design with regards to the bus cycle time, the designer shall take into account the total number of nodes, the amount of I/O data that is to be exchanged and the bus speed.

For any given bus speed, there is a linear relationship between the number of DP-Slaves on the bus, their I/O count and the bus cycle time (i.e. the more Slaves and/or the more I/O bytes per Slave, the longer it takes to complete a bus scan and refresh all inputs and outputs).

The (simplified) formula to calculate the typical bus cycle time in a Mono-Master Profibus DP network is:

Equation 1: Typical DP cycle time equation (Mono-Master system)




𝐷𝐷𝐷𝐷t = 380 + 300 ∗ NDPS + BitDP ∗ TIOB Bsd

+ 0.000075𝑠𝑠

NDPS: Number of DP Slaves (eg 20) BitDP: Bits per DP Byte (constant: 11 bit/byte) TIOB: Total of all Input and Output Bytes (eg 496) Bsd: Bus Speed (in bits per second)

Formula courtesy of Andy Verwer (MMU PROFIBUS Competence Centre)

Note: the above formula assumes an averaged amount of I/O data per Slave (and as such it also assumes that every Slave has input & outputs). It nonetheless provides a good enough indication of the expected typical bus cycle time when operated in normal cyclic I/O data exchange. The number of repeaters or OLMs, Bus retries, or diagnostic data messages etc. are not taken into account.

Even though Water related process control systems typically do not have any high speed I/O reaction or bus cycle time requirements, the following rules apply:

1. The calculated typical bus cycle time shall be able to accommodate the fastest changing input signals.

One example would be flow meter count pulses. If litre pulses are required to be counted at a maximum flow of 10 litres/second, the input would change state every 50 ms at maximum flow. This would require a typical bus cycle time well below 50ms to avoid that pulses can go undetected (which in turn would lead to falsified results of the PLC based totaliser count). Alternative arrangements shall be sought in this case for the affected inputs (e.g. wired back to an Input card in the central rack, usage of high speed counter cards etc.).

2. The calculated typical bus cycle time shall not exceed 100ms. If this can’t be avoided the matter shall be referred to the Principal SCADA Engineer.

Profibus Master configuration tools (e.g. Siemens Step 7) will calculate the typical bus cycle time automatically for any given configuration and may also be used to estimate it.

If PA devices are part of the overall Profibus network, their impact on the DP bus cycle time depends on the type of DP/PA link used.

- Siemens DP/PA Link: The Siemens DP/PA link is a DP Slave which holds and buffers all the values of the underlying PA Slaves (up to 244 Bytes of I/O per DP/PA link). It is simply to be added to the above formula as ONE DP Slave with an I/O count comprising of the sum total of each connected PA Slave.

- P&F DP/PA Gateway: P&F DP/PA Gateway is transparent for the DP Master who treats each PA Slave just like a DP Slave. Each PA Slave with its respective I/O count is as such to be included into the above formula. Note that the Gateway itself is also a DP Slave with 1 Byte I/O.

3.6 Bus speed & Segment Cable Length Profibus offers the choice of 10 different baud rates. The baud rate also determines the maximum permissible RS485 segment length; their relationship is shown in the table below:

Table 8: Profibus DP Maximum Segment length versus Baud rate Baud rate (Kbit/s) 9.6 19.2 45.45 93.75 187.5 500 1500 3000 6000 12000

Segment Length (m) 1000 1000 1000 1000 1000 400 200 100 100 100

Note 1: The Profibus Standard allows 1200m, this has however been limited to 1000m for the purpose of this Standard

Note 2: These lengths are defined for Segments with 32 Devices attached to it.




1500 Kbit/s is the preferred baud rate and the Profibus design should accommodate this baud rate.

500 Kbit/s may be chosen as an alternative (note the bus cycle time impact). This alternative shall however be submitted to the Principal SCADA Engineer for approval.

The design shall show the estimated cable length for each Device and Segment.

Baud rates higher than 1500 Kbit/s are not necessarily supported by all DP Slaves and also require extra care with auxiliary equipment selection. They should be avoided unless specific reasons exists (i.e. Bus cycle time requirements) which warrant its usage.

3.7 Spurlines Spurlines are caused by branches of the main DP bus line and shall NOT be deliberately included in either the design or implementation.

T-Tap orJunction Box

Bus Cable

Spur

DPSlave

Bus Cable

DPSlave

Figure 24: Spurline example Figure 25: Typical “loop through” connection

Points to note:

- The end of a Spurline shall NOT be terminated.

- Spurlines cause problems due to their capacitive influence. Additional devices in the spurline like surge arrestors have a compounding affect and their capacitance shall be taken into account.

Since Spurlines shall not be deliberately included in either the design or implementation, the allowance shown in Table 8 below is to be used only to verify the design which includes equipment with known internal spurlines.

Table 9: Maximum permissible TOTAL Spurline length per Segment versus baud rate Baud rate (Kbit/s) 9.6 19.2 45.45 93.75 187.5 500 1500 3000 6000 12000

Max. TOTAL Spurline Length per Segment (m) 500 500 100 100 33 20 6.6 0! 0! 0!

Max. TOTAL Capacity of Spurs (nF) 15 15 3 3 1 0.6 0.2 0 0 0

Note: The maximum total capacitance of the spur is the same as the maximum total spurline length if type A Profibus cable is used (with <30pF/m).

There may be cases where the “loop through” connection is not feasible to avoid a spurline. This could be due to long cable runs out to an individual device in combination with surge arrestor requirements. A different method to overcome this problem is the usage of a repeater as shown in Figure 25 below.




Bus Cable

DPSlave

Repeater

T

T

Figure 26: DP Repeater usage to avoid spurlines

In this case the repeater creates a complete new RS485 segment, capable of handling up to 31 devices (it is NOT a spurline, note also the termination requirements).

If a number of devices require repeater based connections, the costs aspect of one repeater per device becomes uneconomical (on top of installation and space requirements). In this case devices known as “Repeater Hubs” are to be employed instead. These “Repeater Hubs” are what the name suggests, a number of repeaters bundled inside a single device.

Bus Cable

T

T

T

T

T

T

T

Repeater Hub

DPSlave

DPSlave

DPSlave

DPSlave

AT

DPSlave

T

T

DPSlave

Figure 27: DP Repeater Hub usage example

Just like repeaters, each newly created segment that branches of the hub is a fully fledged RS 485 segment, capable of handling up to 31 devices.

3.8 Termination Each RS 485 segment requires active termination on either end of the segment (active termination refers to the fact that +5V is required to power the termination).

+ 5V

B Line

A Line

GND

390 Ω

220 Ω

390 Ω

Pin 6

Pin 3

Pin 8

Pin 5

DB9

Connector

Figure 28: Profibus DP termination structure and DB9 connector pin assignment.




It is mandatory for a device with a DB9 Connector to comply with the above Pin layout and provide the 5V as well as ground connection. Most DB9 Profibus Plugs have a switchable termination resistor combination inbuilt and as such allow termination via the Plug.

Devices without DB9 connector (e.g. terminal connection, M12 plugs) will typically have switchable termination resistors inbuilt. This shall however be verified in case the device is to be the first or last in the segment.

Note that removal of a DB9 connector with switched on termination in the Plug from a device will lead to a loss of proper segment termination as it removes the 5V as well as the Ground connection and leaves only the 220 Ω between B and A line! Note further that powering off a device at the start or end of the segment will also lead to a loss of proper segment termination!

To overcome the associated risk of upsetting the whole RS 485 segment, external active termination resistors are to be installed if any of the following is true:

- The Segment contains more than 1 DP Slave. - The Segment contains more than 2 Devices with RS485 interface. - In addition, an active terminator shall always be used at the PLC end to aid with the connection

of troubleshooting tools without the need to touch the CPU.

Devices where it is permissible to use inbuilt or DB9 Plug terminations are:

OLMs (in cases where only Slaves are connected on their RS 485 port)

- Repeaters (in cases where only Slaves are connected to the port which creates the new Segment. See also “Notes 1 and 2” in Figure 29 below as an example for this).




DPSlave

T

DPSlave

T

DPSlave

DPSlave AT

Repeater

DPSlave

T T

DPSlave

Repeater

T TDP

SlaveDP

Slave

T

NOT ok. More than 2 Devices with RS 485 interface on one Segment. Active terminating resistor must be used.

NOT ok. More than 1 DP Slave on one

Segment. Active terminating resistor must be used.

DPSlave

NOT ok. More than 1 DP Slave on one

Segment. Active terminating resistor must be used.

NOTE 2:Active terminating resistor required to maintain integrity of this Segment in

case of repeater failure



NOTE 1:OK, if repeater or power to it fails, this

segment will be “lost” anyhow.(Repeater is treated like a DP Master

at Segment start in this case).

DPMasterAT AT

DPMaster

ATDP

Master ATDP

Master

Figure 29: Correct and incorrect DP Segment termination examples

3.9 Certification Designers shall ensure that Profibus Master and Slave devices are certified by a Profibus International approved test laboratory. The Designer shall submit to the Water Corporation a copy of the valid and current certificates for these devices at the time of submitting the Topology drawings for the Water Corporation’s comment.

Device certification gives the user assurance that the device complies with the Profibus specifications and only certified Profibus Masters and Slaves shall be used in the design. Devices (Masters and Slaves) from manufacturers who are unable to supply current and valid certificates for their devices by a Profibus International approved test laboratory shall not be used in the design.

Note that Profibus device certification is only available for Master and Slave devices. Standard Repeaters, OLMs, Plugs or other Profibus items that are neither Master nor Slave are not certifiable (The DP Slave interface functionality of Diagnostic Repeaters or DP/DP couplers for example can be certified though).

3.10 Cable specification DP Cable type A shall be used for all Profibus DP RS485 cables which has the following characteristics:




Parameter Value

Cable design Twisted pair, shielded

Impedance 150 Ω +/- 15 Ω (at 3 to 20Mhz)

Capacitance < 30pF/m

Loop resistance < 110 Ω/km

Wire diameter > 0.64 mm

Core cross section > 0.32 mm2

Table 10: DP cable type A specification




Profibus PA Design 4

4.1 Topology Profibus PA supports tree and linear bus topologies. Unlike DP, connection of PA devices to the bus is typically done via spurlines, which either branch of dedicated junction boxes or individual “T” taps. Note that the 2 wire bus does also serve to supply power to the PA devices.

The topology design drawing shall include the following information:

- Estimated cable length for each cable run. - Termination requirements. - Node addresses. - Current consumption and Voltage drop per PA Segment. - Estimated PA cycle time.

PA “Trunk”

DP/PA Link/

Couplers

24V

PASlave

PASlave

PASlave

PASlave

PASlave

PASlave

“T”Tap

“T”Tap

T

DP network

JunctionBox

PASlave

PASlave

PASlave

PASlave

PASlave

PASlave

PASlave

PASlave

Note: Each PA spurline is assumed to be <= 90m in this example.

PA Device Manager Station (configuration, maintenance, diagnosis …)

JunctionBox T

DPMaster

Gateway

Plant Ethernet network

Figure 30: Typical PA Topology example including termination requirements & Device Manager Station

4.2 DP/PA Link and Coupler selection There are in principal the following two different ways to link a (Manchester bus powered) PA network to a (RS 485) DP network:

1. Directly via PA couplers (NOT TO BE USED)

2. Indirectly via PA couplers behind a DP/PA link (TO BE USED)

Item 1 requires the DP network to operate at reduced baud rates (45.45 for Siemens PA couplers and 93.75 Kbit/s for P&F Segment couplers). PA couplers shall not be directly connected to a DP network and the associated design requirements for direct PA coupler connection to a DP segment will not be further discussed.

This leaves item 2 and the designer is faced with making the choice between a Siemens or a Pepperl & Fuchs or a PROCENTEC based solution.




Siemens, P&F and PROCENTEC employ different strategies concerning the functionality of their DP/PA link/coupler combination. The general differences are outlined in the selection Table 10 below.

Table 11: Siemens versus P&F vs PROCENTEC DP/PA Link selection guide

Manufacturer/

Type

Siemens DP/PA Link

(IM153-2)

P&F DP/PA Link

(HD2-GTR-4PA)

PROCENTEC ComBricks

(Headstation, RS485 or FO DP module and PA link modules)

Gateway functionality

DP/PA Link is a DP Slave.

It is not transparent for the DP Master (PLC). It is however transparent for PA Device Manager/ Configuration tools which are connected to the DP network.

Transparent

(Note that the Link is nonetheless a DP Slave and shall be configured with 1 Byte I/O data)

Transparent

PA Slave addressing

Independent of DP network.

PA Slaves behind the Link do not “consume” DP node addresses.

First usable PA address is 3.

Part of the entire DP network (due to the Links transparency).

Each PA and DP device shall have a unique node address across the whole network.

Part of the entire DP network (due to the Links transparency).

Each PA and DP device shall have a unique node address across the whole network.

Number of PA couplers behind a

DP/PA link 1-5 1-4

1-9

(Note: additional power module required if more than 4 DP or PA modules are in one ComBricks station)

Number of PA Slaves per Coupler

1-31

(Note: see 4.3 below for limits as per this standard)

1-31

(Note: see 4.3 below for limits as per this standard)

1-31

(Note: 4.3 below for limits as per this standard)

Number of PA Slaves per

Link/Coupler arrangement

1-64

(Note: Shall not exceed 244 Bytes of I/O per Link).

1-124 1-124

Number of PA Slaves on one Profibus DP

1-7936

(theoretically, 64 PA Slaves per

1-123

(123 PA Slaves across 4 couplers on one

1-124

(124 PA Slaves across up to 9 couplers on




network. DP/PA Link, 124 links in total) DP/PA Link, note that the Link occupies a node address too).

one DP/PA Link).

Amount of data 244 bytes of I/O for all PA Slaves behind each DP/PA link 244 bytes of I/O per PA device. 244 bytes of I/O per PA device.

Bus parameters Standard Watchdog time of PA network shall be adjusted

Standard

(Note: Caters for individual adjustment though if desired via the Headstations web interface)

Others

Easy to configure if DP Master is a Siemens PLC, more complex to configure if DP Master is a non-Siemens PLC.

GSD files of each PA device shall be converted. P&F does provide a conversion tool for this.

Optional advanced PA network Diagnostic module available.

GSD files of each PA device is recommended to be converted. PROCENTEC does provide a conversion tool for this.

Allows direct fibre optic DP to PA transition.

Out of the box DP and PA diagnostics and 24/7 Network monitoring. (Ethernet connection to ComBricks Headstation required)

NOTE: The above table lists the maximum capabilities for comparison purposes which are not necessarily the permissible values as per this standard.




LInk

C1

C2

C3

C4

C5

1-5 couplersper Link

1-31 PA Slaves per Segment

C1

C2

C3

C4


1-123 PA Slaves per Link

1-31 PA Slaves per Segment.

Each PA Slave with up to 244

Bytes I/O.PA Cycle time per

Segment.

DP/PA link “consumes” 1 DP Slave address.

PA Slaves do NOT “consume” a node address on the DP

network (Link is NOT transparent).

Max. 244 Bytes of I/O for all PA Slaves behind the Link!

DP/PA link “consumes” 1 DP Slave address.

EACH PA slave “consumes” a node address on the DP

network (Link is transparent).

Up to 7936 PA Slaves per DP network

DPMaster


DPMaster

LInk

1-64 PA Slaves per Link.

PA cycle timeper Link.

Siemens DP/PA Link/Couplers Framework(IM153-2)

Pepperl & Fuchs DP/PA Link/Couplers Framework(HD2-GTR-4PA)

PROCENTEC ComBricks DP/PA Link Framework(Headstation, RS485 or FO DP module and PA link modules)

C1

C2 ... C

9


1-124 PA Slaves per Link

1-31 PA Slaves per Segment.

Each PA Slave with up to 244

Bytes I/O.PA Cycle time per

Segment.

EACH PA slave “consumes” a node address on the DP

network (Link is transparent).


DPMaster

DPHS

Diagnostic PC

Figure 31: Siemens versus P&F vs PROCENTEC DP/PA Link Framework overview

Note that Siemens, P&F and PROCENTEC continue to develop their products which may lead to enhanced and/or slightly changed functionalities. It is the designer’s responsibility to be aware of current DP/PA Link and coupler functionality and selection decisions should be based on current information (refer to the product manuals).




4.3 Number of PA Devices per Segment/Coupler While it is in principle permissible to connect up 31 PA Slaves to a PA Segment (Coupler) this is to be avoided for a number of reasons such as PA cycle time considerations, spurline length limitation, etc.

There shall be a maximum of 18 PA Slaves per PA Segment/Coupler.

Note that this number may be further limited by the current consumption, voltage drop and/or required spurline length (see sections 4.4 & 4.5 below for more on this).

If a Siemens DP/PA Link is used, the maximum permissible amount of 244 Bytes of I/O data per DP/PA Link shall also be considered, as this limits the number of PA Slaves DP/PA per Link. For example, if a design has one Siemens DP/PA link with 3 PA Couplers and 18 PA instruments per Coupler, even if each instrument is configured to only transmit one Analogue value (i.e. uses 5 Inputs Bytes), the total amount of Input Bytes would be 270 Bytes for the DP/PA Link (3 Couplers * 18 Instruments * 5 Bytes Input).

Each coupler behind the DP/PA link creates its own PA Segment, if more than 18 PA Slaves are required, it can be achieved by adding another coupler to the existing link or another DP/PA Link/Coupler assembly to the DP network.

Preference should be given to keep the spurline of each connected PA device below 30 meters. This way another 6 PA devices can be added to the PA segment at a later stage and each can still branch off 30 meters from the main PA trunk (see also section 4.4 below for more on this).

4.4 Spurlines, Splices and Cable length The maximum permissible length of a (or each) spurline in a PA segment depends on the total number of spurlines in the segment (note that this is not necessarily the total number of PA devices).

Total Number of Spurlines 1-12 1 -14 15-18 19-24 25-32

Maximum Length of

EACH Spurline (Not Ex) 120m 90m 60m 30m <1m

Maximum Length of

EACH Spurline (Ex) 30m 30m 30m 30m <1m

Table 12: Permissible Spurline length versus total Number of Spurlines per PA segment

“Spurs” with less than 1 meter cable lengths are considered “Splices” and are NOT counted as a spurline. This is an important distinction as using splices may positively affect the maximum available spurline length.

Consider the following example based on a PA segment with a total of 15 PA instruments connected to it:

- The maximum spurline length would be 60 meters if each PA instrument is connected to the PA trunk with a spurline of more than 1 meter in length.

- If it is possible to connect one (or more) PA instruments via a “Splice” to the PA trunk (cable length less than 1 meter), each of the remaining 14 instruments can now be connected with a spurline length of up to 90 meters (there are only 14 spurlines in the system now).

The maximum length of all Splices needs to be checked though and shall comply with the following:

Total PA Segment cable length (including spurs) Maximum TOTAL length of all splices per PA

Segment > 400 meters 8 meters




< 400 meters 2% of total PA cable length Table 13: Permissible Total Splice length versus total PA Segment cable length

The maximum segment length is 1900 meters per PA Segment. Note that the sum of all spurlines shall be included in this value and that it is applicable for usage of Profibus PA cable type A. Note further that this number also depends on the current consumption and voltage drop and spurline length (see sections 4.4 & 4.5 below for more on this).

The PA “Trunk” is the cable between both termination points

DP/PA Link/

Couplers

0.5 m

15m 10m

15m

PASlave

PASlave

PASlave

PASlave

“T”Tap

“T”Tap

T

Spurline

Splice

5m

JunctionBox

20m

Spu

rline

15m Spurline

7m

5mPA

Slave

Spurlines

DPMaster

To be avoided

0.5m

PASlave

4m

PASlave

“T”Tap

11m S

purlineTo be avoided

“T”Tap

JunctionBox

T

Figure 32: PA Segment Spurline, Splice and connection examples

With reference to Figure 31 the following applies to achieve simple, clean and easily maintainable PA architectures:

- Only ONE PA Slave shall be connected to a Spurline (even though the PA standard permits up to three PA Slaves per Spurline it shall be avoided to keep the design “clean”).

- Junction boxes shall NOT be connected to the main trunk via a Spurline (even though this is generally permissible it shall be avoided to keep the design “clean”).

- Preference should be given to the use of Junction boxes with built-in Spurline protection. These monitor the spurline current and protect the bus if a short circuit occurs on a spurline.

4.5 Segment Current consumption and Voltage Drop calculations Owing to the bus powered nature of each PA segment, its design requires calculation of its current consumption and Voltage drop to ensure proper operation.

The formula for the current consumption on a PA segment is:

Equation 2: PA Segment current consumption equation ( ) ( ) ( )DnFDEDnBCFDEDBCDFDEDBCDPASeg IIIIIII ++++++= ...2211

IPAseg < Is

IPAseg: Total current consumption of the Segment

IDxBC: Basic Current consumption of the Device

IDxFDE: Fault Disconnection Electronics Current consumption of the Device

Is: Current Supply of the PA Coupler




PA devices limit their current in case of a failure to avoid short circuiting of the (powered) bus. The fault current is known as the FDE value of the PA device (Fault Disconnection Electronics). The FDE is the maximum current that the PA device may draw on top of its basic current consumption. The FDE value is stated in the manual of the PA device (note that some PA devices do not have an FDE). Since it is unlikely that all devices fault at the same time the following rules apply for the usage of the FDE in the current calculation:

Number of PA devices per Segment

Number of FDEs to be included in current consumption calculation.

Always use highest FDES for worst case scenario

1-5 1

6-10 2

11-15 3

16-20 4

21-25 5

25-31 6

Table 14: FDE inclusion rules based on number of PA devices per Segment

Once the maximum current consumption per PA Segment is known a check is to be made to ensure it does NOT exceed the power supply capability of the chosen PA coupler.

Following this, the voltage on the last PA device is to be calculated and checked (The “last” PA device on the Segment is the one with the longest overall cable length to/from the PA coupler).

The formula for the Voltage drop calculation is:

Equation 3: PA Voltage drop equation:

( )SegcablePASegSLD LRIUU ∗∗−= ULD > Umin

ULD: Bus Voltage on last PA device US: Bus Supply Voltage of the PA Coupler IPAseg: Total current consumption of the Segment Rcable: Cable resistance per unit length (44 Ω/km for PA cable type A) LSeg: Length of ALL cables (including spurlines) in the Segment (in km) Umin: Minimum specified operating voltage of the last PA device

Once the Voltage on the last PA device is calculated a check is to be made to ensure it is NOT below its minimum specified operating voltage for the PA device.

Note: Pepperl & Fuchs Segment checker or ABB’s DTD 100 Profibus Layout tool may also be used for this task; its results do not however relieve the designer from their duty of care.

4.6 Bus cycle time Bus cycle times of PA networks are in general longer compared to DP. DP typical fast I/O updates times are also not required on PA since its purpose is to contain analogue instruments and devices who do not require signal update times in the low millisecond range.

The design shall nonetheless estimate the expected PA cycle time to ensure proper analogue control and PID reaction times.

Due to the fact that Siemens and P&F DP/PA links operate differently in the way they buffer the PA data and handle the underlying PA Segment couplers, they also have different ways to calculate the PA cycle time. To make the PA cycle time calculation independent of the equipment selection, the simplified formula below is to be used irrespective of the employed Links.




The (simplified) formula to calculate the typical PA cycle time is:

Equation 4: PA cycle time equation

AcyclmsNmsNPA addCVPASt +∗+∗= 5.115 NPAS: Number of PA Slaves. 15ms is the typical data exchange time for a Standard PA Slave with one cyclic value (i.e. 5 Bytes of data)

NaddCV: Number of every additional cyclic analogue value (5 bytes long) which increases the cycle time by an average of 1.5 ms.

Acycl: Additional Acyclic component caused by the Device Manager Station (for configuration, calibration, device data backup etc.). Assumed to be 20ms.

Siemens Link/coupler Note: The calculated PA bus cycle time is applicable for the whole PA network behind the DP/PA link irrespective if the PA Slaves are located on one or across a number of couplers behind the link.

P&F Link/coupler Note: The calculated PA bus cycle time is applicable and shall be calculated for each individual PA segment behind the DP/PA link.

4.7 Termination Each PA segment requires termination on either end of the segment. PA termination differs from DP termination and comprises of a 100Ω (+/- 2 Ω) resistor in series with a 1μF (+/- 0.2 μF) capacitor.

Segment couplers (at the beginning of the PA trunk) have built in terminators. In some couplers the terminator can be switched off, in other it is always terminated at the coupler. Some junction boxes have a built in terminator that can be switched on or off when required. Unlike DP devices, the vast majority of PA devices do not have inbuilt terminators.

The following PA termination rule applies (see also Figure 29):

- PA termination shall always be activated at the segment coupler which is considered the start of the segment. The PA cable shall not be looped through the Segment coupler.

- The other termination shall be made via an external PA terminator which has to be located in close proximity to the “last” junction box (the one farthest from the PA Coupler). Even though non-EX rated PA junction boxes usually offer switchable inbuilt PA termination, this shall not be used.

4.8 Device Manager PC A PA Device Manager PC shall be included as part of the design.

This PC will be a permanent part of the installation and requires a connection to the Profibus DP network (not the PA segments, the Device Manager software on the PC will access the PA instruments via the DP/PA link).

Connection of the PC to the DP network is possible in two different ways:

1. Indirectly via an Ethernet to Profibus DP Gateway.

Indirectly by means of routing through the PLC onto the Profibus network.

The connection to the DP network via method 1 or 2 also means that a node address is required for the Gateway or PC on the DP network. This is to be a Master node address and shall be the next free address within the Master address range as per Table 6.

Preference shall be given to method 1 which has the following advantages over method 2:




- The PC can be located anywhere on the SCADA Ethernet network (i.e. no need to run/extend the Profibus cable to where the PC is meant to be located).

- One Device Manager PC can be used for all devices even if more than Profibus network (or PLCs with Profibus networks) exists in the Plant.

Method 3 is a Siemens specific method and requires S7-400 hardware (and Siemens PDM Device Manager software). It shall only be considered for larger Plants which have been designated to be a Siemens PCS7 application.

4.9 Certification Only certified PA slaves shall be used in the design.

4.10 Cable specification PA Cable type “A” shall be used for all Profibus PA cables, it has the following characteristics:

Parameter Value

Cable design Twisted pair, shielded

Nominal Conductor cross sectional area 0.8 mm2 (AWG 18)

Loop resistance (direct current) 44 Ω/km

Impedance (31.25kHz) 100 Ω (+/- 20%)

Attenuation (39 kHz) 3 db/km

Capacitive asymmetry 2 nF/km

Max. propagation delay change (7.9 to 39 kHz) 1.7 μsec/km

Shield coverage 90%

Table 15: PA cable Type A specification

4.11 Explosion Safety Explosion safety for Profibus PA is based on the FISCO model (Fieldbus Intrinsically Safe Concept, developed by the German Federal Physical Technical Institute in cooperation with manufactures).

The FISCO model considerably simplifies the design requirements, installation and operation of Profibus PA in hazardous areas. The model is based on the specification that a network is intrinsically safe and requires no individual intrinsic safety calculations when the relevant four bus components (field devices, cables, segment couplers and bus terminators) fall within predefined limits with regard to voltage, current, power, inductance and capacity.

Intrinsically safe design for usage of Profibus PA in hazardous areas shall be done by a person whose relevant competencies have been formally assessed as stated in DS 28.

The FISCO model is based on the following prerequisites which are to be adhered too in the PA Ex design:

1. To transmit power and data the bus system uses the physical configuration as defined by IEC 61158-2 (which is the case with Profibus PA for example).

2. Each bus station shall fulfil the following capacitive and inductive requirements:

- C < 5 nF

- L < 10µH

3. The basic current consumption of a bus station is at least 10mA.




4. The Bus shall be terminated at both ends with a PA typical RC terminator combination that complies with the following:

- R = 90 … 100 Ω

- C = 0 … 2.2 µF

5. Only one active source is permitted on a bus segment (i.e. the PA coupler/PA power module), all other components work as passive current sinks.

6. The Power, Current and Voltage that each device is capable of handling shall be greater or equal to the Power, Current and Voltage that is supplied to it. In other words, the following applies:

- UIn > UOut of related piece of equipment (e.g. PA coupler, Segment protector)

- IIn > IOut of related piece of equipment (e.g. PA coupler, Segment protector)

- PIn > POut of related piece of equipment (e.g. PA coupler, Segment protector)

7. The maximum permissible PA bus length including all spurlines is 1000 meters.

8. The maximum permissible Spurline length is 30 meters.

9. Bus cable shall comply with the following specification:

- R’ = 15 … 150 Ω/km

- L’ = 0.4 … 1 mH/km

- C’ = 80 … 200 nF/km

Note that PA Cable type “A” fulfils this criteria.

Only FISCO certified devices are to be used in intrinsically safe PA designs which also automatically ensures adherence to the requirements of item 2, 3 and 4.




Installation 5This chapter assumes that the Plant design incorporates a proper earthing and equipotential bonding regime.

The Installer shall comply with the DP, PA and Profinet installation guidelines as listed in section 1.6.

5.1 Shield connection The Profibus or Profinet cable shield shall always be connected at both ends of each cable run. The only exception to this rule may come from installation requirements in hazardous areas where, for instance, a capacitive shield connection may be called for (the design of this is to be done by a person whose relevant competencies have been formally assessed.)

The cable shield shall be connected to a functional earth where the cable enters (or exits) a cabinet as shown in Figure 33 below. Note that these shall not be used as a substitute for strain relief. Care shall be taken when cutting off the outer sheath of the cable to avoid damage to the shield braid.

Figure 33: Cabinet entry/exit points cable shield connection examples (courtesy Siemens Simatic Profibus Networks Manual)

Pigtails shall not be used to connect the shield to the functional earth. Pigtails create an inductance which effectively renders the shield to earth connection useless against high frequency interference. Instruments or devices without provision for a shield clamp (i.e. terminal connection only) should be avoided.

In-line DIN rail mounted Surge arrestors shall be equipped with a shield clamp as shown in Figure 34 below.

Figure 34: Shield clamp usage for DIN rail mounted surge arrestors (courtesy Siemens Simatic Profibus Networks Manual)

5.2 Cable handling and protection Care shall be taken to prevent damage due to excessive tension or pressure, kinking or twisting as well as bending radius violations.




Manufactures specify a maximum tensile strength for the cable which shall not be exceeded during the cable installation (e.g. pull by hand only without applying force).

Maximum bending radii as per the cable manufactures’ specifications shall be observed (if these are not available the radius shall be greater than 10 times the cable diameter for permanent installations). This is particularly important during installation within cabinets where excess cable is being “stored” within the duct.

Cables shall not be run or laid over sharp edges. Cable glands are to be used for entry and exit to cabinets.

Sections of cable which have been exposed to undue stress (e.g. been accidentally squashed, pinched, kinked, twisted, stepped on etc.) shall not be used for the installation.

5.3 Cable spacing Cables are classified into the following 4 categories according to their voltage level and application:

Category I: Bus signals, shielded (e.g. Profibus, Profinet, Ethernet) Bus signals, unshielded (e.g. AS-Interface) Data signal, shielded (e.g. Printer, counter inputs etc.) Analog signals, shielded (< 25V) Digital Process signals, unshielded (< 25V) DC Voltage, unshielded (< 60V) AC Voltage, unshielded (< 25V)

Category II: DC Voltage, unshielded (>60V and < 400V)

AC Voltage, unshielded (>25V and < 400V)

Category III: DC and AC Voltage, unshielded (> 400V)

Telephone cable

Category IV: Category I to III cables with direct danger of lightning strike

Cables from within each category can be laid together in common bundles or cable channels.

Figure 35 below shows the required clearance of Profibus or Profinet cables to cables from the other categories if placed side by side. Cables of different categories may only cross each other at a 90 degree angle.




Figure 35: Air gaps Cable spacing requirements (side by side cable placement)

If it is not possible to maintain these distances, the Profibus or Profinet cable shall be run in steel conduits or segregated from the other category cables by means of metallic partitioning of the cable tray. Metallic partitions shall be electrically bonded to the cable tray.

5.4 Fast connect system Only Fast Connect Cable and Fast Connect Plugs shall be used for the installation. Cable stripping is to be done with the applicable Fast Connect Stripping tool. This avoids any potential for time consuming and costly troubleshooting of the connection due to improper Stanley knife related cable stripping.

5.5 Minimum Profibus DP cable length between devices Irrespective of the chosen baud rate, a minimum of 1 meter cable shall be installed between two neighbouring devices with an RS485 interface.

5.6 DB9 Connectors and Profibus installation cable path

Make sure that the Cable Shield is in correct position

to ensure full proper contact with shield clamp

in Plug!

Terminator ON

Terminator OFF

If termination is ON, the second channel is disconnected.

DB9 connection for first and last station on the bus

DB9 connection for all other stations on the bus

A1

B1

A2

B2

A1

B1

A2

B2

Figure 36: DB9 Connector cable connection

50cm

10cm

10cm

50cm

50cm

20cm

Cable Category II

Cable Category III

Cable Category I

Cable Category IV




Figure 36, above, shows the correct connection method for DB9 connectors and what to watch out for. Note that switching on the inbuilt termination resistor does not only “activate” the termination resistors but more importantly disconnects the outgoing channel. Only DB9 plugs that offer this feature are to be used (see recommend equipment list).

The disconnection functionality of the second channel is a very useful “feature”. It greatly helps in cases of troubleshooting Profibus installations or if parts of the installation are required to be taken out for maintenance work while maintaining the remaining bus with proper termination. For it to be properly utilised though, the following cable path rule shall be adhered to:

Starting from the DP Master (PLC), the Profibus cable shall loop through each DB9 Plug by “entering” it on the “left” and “leaving” it on the right as shown above (“left” and “right” as per above).

DPMaster

DPSlave

DPSlave

DPSlave

DPSlave

DPSlave

DPSlave

AT

Normal Situation

DPMaster

DPSlave

DPSlave

DPSlave

DPSlave

DPSlave

DPSlave

AT

Plug with Terminator ON

Plug with Terminator OFF

Troubleshooting situation

Activation of Plug Terminator isolates downstream path

Figure 37: Designated Profibus Cable path example

Loop through connection on devices without DB9 connectors (e.g. terminal strip connection or M12 Plugs) still require adherence to the cable path rule.




PLC and SCADA configuration 6

6.1 PLC configuration Each PLC vendor uses their own configuration software to allow creation of Profibus or Profinet related setup. While there may be differences in the user interface, the common aim is to facilitate the setup of the bus parameters and configuration of all Devices irrespective of the manufacturer.

6.1.1 GSD files 6.1.1.1 Profibus

Configuration of each DP or PA Slave requires a corresponding GSD file for each Slave. A Profibus DP or PA Device Manufactures may enhance or further develop the functionality of their products. Since this may lead to revised GSD file being available it is imperative that the correct GSD file version for the chosen Slave is being used for the DP Master configuration.

6.1.1.2 Profinet GSDML files are used for the integration and configuration of Profinet I/O Devices. GSDML files are simply GSD files written in XML (Extensible Markup Language). As with GSD files, it is imperative that the correct GSDML file version for the chosen I/O Device is being used for the I/O Controller configuration.

6.1.2 Device Watchdog time (Response monitoring) Profibus Slaves and Profinet I/O devices incorporate a Watchdog functionality (sometimes also called “response monitoring”). This is a time based monitoring mechanism inside the Device which monitors the repeated (cyclic) occurrence of communication with the PLC. Devices will go into a safe state upon expiry of their watchdog time. This is an important and useful feature to avoid potentially dangerous Plant states in cases of communication problems or bus failures.

Depending on the Device and implemented functionality (consult the device manual), it may support entering different pre-defined “Safe States” upon detection of a bus fault.

Safe state examples for a Valve actuator may entail:

- Stay (e.g. actuator will remain in last position) - Open (e.g. actuator will open fully) - Close (e.g. actuator will close fully) - Move to position x (actuator will move to a configurable position value)

The following rules apply for Watchdog monitoring:

• Watchdog monitoring shall be enabled for each Device.

• The Safe state position needs to be defined for each Device and configured accordingly in the DP Master or I/O Controller setup

The Safe state position needs to be defined for each Device and configured accordingly in the DP Master or I/O Controller setup.

6.1.3 DP Master or I/O Controller bus monitoring While the Devices themselves will go into a safe state if communication with the PLC is lost, the DP Master or I/O Controller will also recognise “lost” devices. The associated PLC logic shall capture Devices’ communication faults/dropouts (per individual Device) and raise a SCADA Alarm (per individual Device) to inform the Operators that either device control has been lost and/or inputs are no longer updated.




6.2 Diagnostics Apart from the “normal” cyclic I/O data exchange between each Slave and the PLC, Devices are also capable of issuing Diagnostics data.

6.2.1 Profibus Diagnostics The format of the first 6 Bytes of the diagnostic message are standardised cannot be changed by the slave manufacturer. These 6 Bytes are the so called “Standard Diagnostics” and contain general information related to the slave (e.g. the Device ID number, bits to indicate if it is parameterised, in data exchange etc.).

Following these, the device/instrument manufacturer may choose to develop and add extended diagnostic information which is specific for their device. The manufacturer decides on the meaning and length of the extended diagnostic data for their Slave.

“Simple” slaves (usually non-modular ones like flow meters, pressure transmitters, valve actuators, drives etc.) will typically have a predetermined fixed amount of extended diagnostic data. The assignment of which bit has what meaning in the extended diagnostic messages can be found in the slave manual and/or its GSD file (Note that not all manufactures chose to add these to the GSD file).

An example of some of the extended diagnostics bits from Profibus PA pressure transmitter are:

Unit_Diag_Bit(24) = "Hardware failure electronics" Unit_Diag_Bit(27) = "Electronic temperature too high" Unit_Diag_Bit(29) = "Measurement failure" Unit_Diag_Bit(31) = "Device initialization failed" Unit_Diag_Bit(32) = "Zero point error" Unit_Diag_Bit(33) = "Power supply failed" Unit_Diag_Bit(34) = "Configuration invalid" Unit_Diag_Bit(66) = "A115: Sensor overpressure" Unit_Diag_Bit(68) = "A120: Sensor underpressure" Unit_Diag_Bit(72) = "A610: Calibration error"

An example of all of the extended diagnostics bits from a Profibus DP valve actuator are:

Unit_Diag_Bit(24) = "Motor Thermostat" Unit_Diag_Bit(25) = "HI-HI Torque in Opening" Unit_Diag_Bit(26) = "HI-HI Torque in Closing" Unit_Diag_Bit(27) = "Actuator blocked in Opening" Unit_Diag_Bit(28) = "Actuator blocked in Closing" Unit_Diag_Bit(29) = "HI-HI Temperature" Unit_Diag_Bit(30) = "Position Sensor Failure" Unit_Diag_Bit(31) = "Speed Sensor Failure" Unit_Diag_Bit(32) = "Main Voltage Fault" Unit_Diag_Bit(33) = "K1 Contactor Failure" Unit_Diag_Bit(34) = "K2 Contactor Failure" Unit_Diag_Bit(35) = "Configuration Error" Unit_Diag_Bit(36) = "Hardware Error" Unit_Diag_Bit(37) = "Low Alkaline Battery" Unit_Diag_Bit(38) = "Lost Phase" Unit_Diag_Bit(39) = "No response from base card"

A slave will only inform the DP Master about the availability of diagnostic data if and when the need arises. The DP Master will then automatically request these diagnostic data the next time it polls the Slave.




Diagnostic data of more “complex” slaves (e.g. modular I/O stations) on the other hand are generally not fixed in their length and/or assignment of bits (owing to the freely configurable nature of the Slave). While this makes PLC logic based evaluation of the received diagnostic data more “complex” too, it is still desirable to do so.

As it can be seen from the above examples, diagnostic data yield important additional information about the status of the slave, as such the following applies for the evaluation of them in the PLC logic and SCADA system:

1. A general “Received Diagnostic message from slave xyz” is to be generated for every slave (DP or PA, modular or not modular slave) and alarmed on the SCADA system.

2. A detailed diagnostic (popup) screen is to be configured for each slave with fixed Diagnostic data assignment. This screen will display the details of the diagnostic message. Consideration should be given to develop these for all Slaves including “complex” ones.

Alternatively, a dedicated Diagnostic Station PC may be employed to allow read out and evaluation of slave diagnostic data (Class 2 Master functionality). In cases where PA instruments are used, the PA Device Manager Station PC shall be set up and used for this purpose.

6.2.2 Profinet Diagnostics While even more comprehensive than Profibus Diagnostic data, the same intent and handling as described in 6.2.1 above applies.

Figure 38: Siemens ET200MP GSDML file channel Diagnostic example




Figure 39: Danfoss FC Series drive GSDML file channel Diagnostic example

6.3 Profibus DP Bus parameters DP master configuration tools will generally opt for the default bus parameters as shown below for 500 and 1500 kbit/s.

500 kbit/s 1500 kbit/s TSlot (bit times) 200 300

Max. TSDR (bit times) 100 150

Min. TSDR (bit times) 11 11

TSet (bit times) 1 1

TQuiet (bit times) 0 0

Gap factor 1 10

Retry Limit 1 1

HSA 126 126

Table 16: Default DP Bus parameters vs. Baud rate

The following three parameters of each DP network are to be modified in the configuration (this improves network stability in general and allows “ride through” of short lived interference):

Retry limit: Change from 1 to 5

Min. Tsdr: Change from 11 to 22

TQuiet: Change from 0 to 9




Appendix 7

7.1 List of figures Figure 1: Profinet Line Topology example 15 Figure 2: Profinet Line Topology example detail 15 Figure 3: Profinet Star Topology example 16 Figure 4: Profinet Tree Topology example 1 (multiple Star Topologies) 16 Figure 5: Profinet Tree Topology example 2 (Line and Star topology combined) 17 Figure 6: Profinet I/O Controller/Devices inbuilt switches based MRP Ring Topology example (information only, NOT to be used in the design) 17 Figure 7: Profinet Switches based MRP Ring Topology example (MRP and Star combined) 18 Figure 8: Line Topology Network Load example (1ms update time, 24 Bytes Inputs and Outputs per I/O device) 22 Figure 9: Star Topology Network Load example (1ms update time, 24 Bytes Inputs and Outputs per I/O device) 22 Figure 10: Network load calculation tool usage example 23 Figure 11: Example SCADA and OIP connection 24 Figure 12: NOT allowed - multiple PLCs on one Profinet Network 25 Figure 13: Allowed - each PLC with its own Profinet Network 26 Figure 14: S7-400 H System "Open Ring" Profinet Network example 27 Figure 15: S7-400 H System with redundant Profinet Networks example 27 Figure 16 S7-400 H System with redundant Profinet Networks with “Y” switch 28 Figure 17: PN/PA Proxy usage example 29 Figure 18: PN/DP Proxy usage example 30 Figure 19 Example Fibre Optic Line Topology 33 Figure 20 Example Fibre Optic Ring Topology 33 Figure 21 Example Fibre Optic Star Topology 34 Figure 22: Example RS 485 Line Topology 35 Figure 23: Example RS 485 Tree Topology 35 Figure 24: Spurline example Figure 25: Typical “loop through” connection 39 Figure 26: DP Repeater usage to avoid spurlines 40 Figure 27: DP Repeater Hub usage example 40 Figure 28: Profibus DP termination structure and DB9 connector pin assignment. 40 Figure 29: Correct and incorrect DP Segment termination examples 42 Figure 30: Typical PA Topology example including termination requirements & Device Manager Station 44 Figure 31: Siemens versus P&F vs PROCENTEC DP/PA Link Framework overview 47 Figure 32: PA Segment Spurline, Splice and connection examples 49 Figure 33: Cabinet entry/exit points cable shield connection examples (courtesy Siemens Simatic Profibus Networks Manual) 54 Figure 34: Shield clamp usage for DIN rail mounted surge arrestors (courtesy Siemens Simatic Profibus Networks Manual) 54 Figure 35: Air gaps Cable spacing requirements (side by side cable placement) 56 Figure 36: DB9 Connector cable connection 56 Figure 37: Designated Profibus Cable path example 57 Figure 38: Siemens ET200MP GSDML file channel Diagnostic example 60 Figure 39: Danfoss FC Series drive GSDML file channel Diagnostic example 61

7.2 List of Tables Table 1: S7 CPU examples for I/O Device capability 19

Table 2: Profinet I/O devices 70% rule design limit 20

Table 3: Profinet update times selection table 21

Table 4: Network Load examples (24 Bytes of Inputs and 24 Bytes of Outputs per I/O Device) 22

Table 5: PN/DP Proxies differences 30

Table 6: DP Node address assignment Error! Bookmark not defined.

Table 7: Profibus DP Maximum Segment length versus Baud rate 38




Table 8: Maximum permissible TOTAL Spurline length per Segment versus baud rate 39

Table 9: DP cable type A specification Error! Bookmark not defined.

Table 10: Siemens versus P&F vs PROCENTEC DP/PA Link selection guide 45

Table 11: Permissible Spurline length versus total Number of Spurlines per PA segment Error! Bookmark not defined.

Table 12: Permissible Total Splice length versus total PA Segment cable length Error! Bookmark not defined.

Table 13: FDE inclusion rules based on number of PA devices per Segment Error! Bookmark not defined.

Table 14: PA cable Type A specification Error! Bookmark not defined.

Table 15: Default DP Bus parameters vs. Baud rate Error! Bookmark not defined.

7.3 List of Equations Equation 1: Typical DP cycle time equation (Mono-Master system)(1) 37

Equation 2: PA Segment current consumption equation 49

Equation 3: PA Voltage drop equation: 50

Equation 4: PA cycle time equation 51




7.4 Explanatory notes for Topology drawing 1 (Profibus with Siemens PA Link/Coupler) DP Devices overview table

Node Type Input Bytes Output Bytes Comments 10 Filter 1 I/O station 8 8 2*32 channel Digital input cards, 2*32 channel Digital output cards

11 Filter 1 DP/PA link 45 0 Number of Input and Output Bytes is the sum of underlying PA devices Input and Output Bytes.

12 Filter 1 Valve 1 8 4 Based on data sheet of selected Valve



20 Filter 2 I/O station 8 8 See Filter 1

21 Filter 2 DP/PA link 45 0 See Filter 1

22 Filter 2 Valve 1 8 4 See Filter 1













101 VSD 1 28 28 PPO 5 type selected




I/O Bytes Total 420 192




PA Devices overview table (Shown for one Filter, Filter 1-4 PA segments are identical)

Node Type AI/AO values Current consumption FDE Min. operating Voltage Comments 3 Flow Transmitter 2 12 mA 10 mA 9 V Actual Flow and Totaliser value

4 Pressure Transmitter 1 11 mA 0 mA 9 V

5 Level transmitter 1 11 mA 0 mA 9 V

7 Pressure Transmitter 1 11 mA 0 mA 9 V

8 Flow Transmitter 2 12 mA 10 mA 9 V Actual Flow and Totaliser value

9 Analytical Transmitter 2 11 mA 5 mA 9 V PH and temperature value

7.4.1 Estimated DP cycle time: Summary for calculation: Number of DP Slaves: 24 Total of all Input and Output Bytes: 612

Estimated DP cycle time: 𝐷𝐷𝐷𝐷t = 380 + 300 ∗ NDPS + BitDP ∗ TIOB Bsd

+ 0.000075𝑠𝑠 = 9.6 ms

7.4.2 Estimated PA cycle time: Summary for calculation: Number of PA Slaves: 6 Number of additional cyclic values: 3

Estimated PA cycle time msmsmsPAt 205.13156 +∗+∗= = 114.5 ms (per Filter)

7.4.3 PA current consumption: Summary for calculation: Number of FDE currents to be used: 2 (6-10 PA devices) PA couplers supply capacity: 1000 mA PA current consumption: ( ) ( ) ( ) ( ) ( ) ( )mAmAmAmAmAmAmAmAI PASeg 1110121111111012 +++++++= = 88.0 mA (per Filter) Result: OK (1000 mA available, 88 mA required)




7.4.4 PA Voltage drop calculation: Summary for calculation: PA Cable length: 106 m (trunk length + length of all spurlines) PA couplers supply voltage: 31 V

PA Voltage drop calculation: ( )mAVU LD 106 /m 044.0088.031 ∗Ω∗−= = 30.59 V (at the PA device furthest from the Coupler)

Result: OK (30.59 V available, 9 V required)

7.5 Explanatory notes for Topology drawing 2 (Profibus with P&F PA Link/Coupler) DP Devices overview table (Note: PA Slaves are counted as DP Slaves due to the DP/PA links transparency)

Node Type Input Bytes Output Bytes Comments 10 Filter 1 I/O station 8 8 2*32 channel Digital input cards, 2*32 channel Digital output cards 11 Filter 1 DP/PA link 1 1 Link is transparent but does have a Node address and 1 byte of input & output data 12 Filter 1 Valve 1 8 4 Based on data sheet of selected Valve 13 Filter 1 Valve 2 8 4 Based on data sheet of selected Valve 14 Filter 1 Valve 3 8 4 Based on data sheet of selected Valve 15 Filter 1 FT (PA device) 10 0 16 Filter 1 LT (PA device) 5 0 17 Filter 1 PT (PA device) 5 0 19 Filter 1 PT (PA device) 5 0 20 Filter 1 FT (PA device) 10 0 21 Filter 1 AT (PA device) 10 0 30 Filter 2 I/O station 8 8 31 Filter 2 DP/PA link 1 1 32 Filter 2 Valve 1 8 4 33 Filter 2 Valve 2 8 4 34 Filter 2 Valve 3 8 4 35 Filter 2 FT (PA device) 10 0 36 Filter 2 LT (PA device) 5 0 37 Filter 2 PT (PA device) 5 0 39 Filter 2 PT (PA device) 5 0 40 Filter 2 FT (PA device) 10 0 41 Filter 2 AT (PA device) 10 0 50 Filter 3 I/O station 8 8 51 Filter 3 DP/PA link 1 1 52 Filter 3 Valve 1 8 4 53 Filter 3 Valve 2 8 4 54 Filter 3 Valve 3 8 4 55 Filter 3 FT (PA device) 10 0 56 Filter 3 LT (PA device) 5 0




57 Filter 3 PT (PA device) 5 0 59 Filter 3 PT (PA device) 5 0 60 Filter 3 FT (PA device) 10 0 61 Filter 3 AT (PA device) 10 0 70 Filter 3 I/O station 8 8 71 Filter 3 DP/PA link 1 1 72 Filter 3 Valve 1 8 4 73 Filter 3 Valve 2 8 4 74 Filter 3 Valve 3 8 4 75 Filter 3 FT (PA device) 10 0 76 Filter 3 LT (PA device) 5 0 77 Filter 3 PT (PA device) 5 0 79 Filter 3 PT (PA device) 5 0 80 Filter 3 FT (PA device) 10 0 81 Filter 3 AT (PA device) 10 0 101 VSD 1 28 28 PPO 5 type selected 102 VSD 2 28 28 PPO 5 type selected 103 VSD 3 28 28 PPO 5 type selected 104 VSD 4 28 28 PPO 5 type selected I/O Bytes Total 424 196

PA Devices overview table (Shown for one Filter, Filter 1-4 PA segments are identical, only Node addresses differ)

Node Type AI/AO values Current consumption FDE Min. operating Voltage Comments

3 Flow Transmitter 2 12 mA 10 mA 9 V Actual Flow and Totaliser value

4 Pressure Transmitter 1 11 mA 0 mA 9 V 5 Level transmitter 1 11 mA 0 mA 9 V 7 Pressure Transmitter 1 11 mA 0 mA 9 V 8 Flow Transmitter 2 12 mA 10 mA 9 V Actual Flow and Totaliser value 9 Analytical Transmitter 2 11 mA 5 mA 9 V PH and temperature value

7.5.1 Estimated DP cycle time: Summary for calculation: Number of DP Slaves: 48 (PA Slaves are counted as DP Slaves due to links transparency) Total of all Input and Output Bytes: 620


+ 0.000075𝑠𝑠 = 14.5ms




7.5.2 Estimated PA cycle time: Summary for calculation: Number of PA Slaves: 6 Number of additional cyclic values: 3

Estimated PA cycle time msmsmsPAt 205.13156 +∗+∗= = 114.5 ms (per Filter)

7.5.3 PA current consumption: Summary for calculation: Number of FDE currents to be used: 2 (6-10 PA devices) PA couplers supply capacity: 500 mA PA current consumption: ( ) ( ) ( ) ( ) ( ) ( )mAmAmAmAmAmAmAmAI PASeg 1110121111111012 +++++++= = 88.0 mA (per Filter) Result: OK (500 mA available, 88 mA required)

7.5.4 PA Voltage drop calculation: Summary for calculation: PA Cable length: 106 m (trunk length + length of all spurlines) PA couplers supply voltage: 30.0 V

PA Voltage drop calculation: ( )mAVU LD 106 /m 044.0088.030 ∗Ω∗−= = 29.59 V (at the PA device furthest from the Coupler)

Result: OK (29.59 V available, 9 V required)




7.6 Explanatory notes for Topology drawing 3 (Profibus with pure DP network, no PA) DP Devices overview table

Node Type Input Bytes Output Bytes Comments 10 Filter 1 I/O station 24 8 2*32 channel Digital input cards, 2*32 channel Digital output cards, 1*8channel Analogue input card 11 Filter 1 Valve 1 8 4 Based on data sheet of selected Valve 12 Filter 1 Valve 2 8 4 Based on data sheet of selected Valve 13 Filter 1 Valve 3 8 4 Based on data sheet of selected Valve 20 Filter 2 I/O station 24 8 See Filter 1 21 Filter 2 Valve 1 8 4 See Filter 1 22 Filter 2 Valve 2 8 4 See Filter 1 23 Filter 2 Valve 3 8 4 See Filter 1 30 Filter 3 I/O station 24 8 See Filter 1 31 Filter 3 Valve 1 8 4 See Filter 1 32 Filter 3 Valve 2 8 4 See Filter 1 33 Filter 3 Valve 3 8 4 See Filter 1 40 Filter 4 I/O station 24 8 See Filter 1 41 Filter 4 Valve 1 8 4 See Filter 1 42 Filter 4 Valve 2 8 4 See Filter 1 43 Filter 4 Valve 3 8 4 See Filter 1 101 VSD 1 28 28 PPO 5 type selected 102 VSD 2 28 28 PPO 5 type selected 103 VSD 3 28 28 PPO 5 type selected 104 VSD 4 28 28 PPO 5 type selected I/O Bytes Total 304 192

7.6.1 Estimated DP cycle time: Summary for calculation: Number of DP Slaves: 20 Total of all Input and Output Bytes: 496


+ 0.000075𝑠𝑠 = 7.9ms

7.7 Explanatory notes for Topology drawing 4 (pure Profinet) I/O Devices overview table

IP Address Type Input Bytes Output Bytes Comments 192.168.0.2 Switch 0 0 No cyclic I/O’s, excluded from calculation




192.168.0.3 Switch 0 0 No cyclic I/O’s, excluded from calculation 192.168.0.4 Switch 0 0 No cyclic I/O’s, excluded from calculation 192.168.0.5 Switch 0 0 No cyclic I/O’s, excluded from calculation 192.168.0.6 Switch 0 0 No cyclic I/O’s, excluded from calculation 192.168.0.10 Filter 1 I/O station 24 8 2*32 channel Digital input cards, 2*32 channel Digital output cards, 1*8channel Analogue input card 192.168.0.11 Filter 1 Valve 1 8 4 Based on data sheet of selected Valve 192.168.0.12 Filter 1 Valve 2 8 4 Based on data sheet of selected Valve 192.168.0.13 Filter 1 Valve 3 8 4 Based on data sheet of selected Valve 192.168.0.20 Filter 2 I/O station 24 8 See Filter 1 192.168.0.21 Filter 2 Valve 1 8 4 See Filter 1 192.168.0.22 Filter 2 Valve 2 8 4 See Filter 1 192.168.0.23 Filter 2 Valve 3 8 4 See Filter 1 192.168.0.30 Filter 3 I/O station 24 8 See Filter 1 192.168.0.31 Filter 3 Valve 1 8 4 See Filter 1 192.168.0.32 Filter 3 Valve 2 8 4 See Filter 1 192.168.0.33 Filter 3 Valve 3 8 4 See Filter 1 192.168.0.40 Filter 4 I/O station 24 8 See Filter 1 192.168.0.41 Filter 4 Valve 1 8 4 See Filter 1 192.168.0.42 Filter 4 Valve 2 8 4 See Filter 1 192.168.0.43 Filter 4 Valve 3 8 4 See Filter 1 192.168.0.101 VSD 1 28 28 PPO 5 type selected 192.168.0.102 VSD 2 28 28 PPO 5 type selected 192.168.0.103 VSD 3 28 28 PPO 5 type selected 192.168.0.104 VSD 4 28 28 PPO 5 type selected I/O Bytes Total 304 192




7.7.1 Estimated Network load: Summary for calculation: Number of I/O devices: 20 Average Input Bytes per I/O device: 16 (Roundup 304/20) Average Output Bytes per I/O device: 10 (Roundup 192/20) Result: 0.88% Network load




7.8 Explanatory notes for Topology drawing 5 (Profinet with GSDML file based PA proxy) I/O Devices overview table

IP Address Type Input Bytes Output Bytes Comments 192.168.0.2 Switch 0 0 No cyclic I/O’s, excluded from calculation 192.168.0.3 Switch 0 0 No cyclic I/O’s, excluded from calculation 192.168.0.4 Switch 0 0 No cyclic I/O’s, excluded from calculation 192.168.0.5 Switch 0 0 No cyclic I/O’s, excluded from calculation 192.168.0.6 Switch 0 0 No cyclic I/O’s, excluded from calculation 192.168.0.10 Filter 1 I/O station 8 8 2*32 channel Digital input cards, 2*32 channel Digital output cards 192.168.0.11 Filter 1 PN/PA proxy 45 0 Number of Input and Output Bytes is the sum of underlying PA devices Input and Output Bytes. 192.168.0.12 Filter 1 Valve 1 8 4 Based on data sheet of selected Valve 192.168.0.13 Filter 1 Valve 2 8 4 Based on data sheet of selected Valve 192.168.0.14 Filter 1 Valve 3 8 4 Based on data sheet of selected Valve 192.168.0.20 Filter 2 I/O station 8 8 See Filter 1 192.168.0.21 Filter 2 PN/PA proxy 45 0 See Filter 1 192.168.0.22 Filter 2 Valve 1 8 4 See Filter 1 192.168.0.23 Filter 2 Valve 2 8 4 See Filter 1 192.168.0.24 Filter 2 Valve 3 8 4 See Filter 1 192.168.0.30 Filter 3 I/O station 8 8 See Filter 1 192.168.0.31 Filter 3 PN/PA proxy 45 0 See Filter 1 192.168.0.32 Filter 3 Valve 1 8 4 See Filter 1 192.168.0.33 Filter 3 Valve 2 8 4 See Filter 1 192.168.0.34 Filter 3 Valve 3 8 4 See Filter 1 192.168.0.40 Filter 4 I/O station 8 8 See Filter 1 192.168.0.41 Filter 4 PN/PA proxy 45 0 See Filter 1 192.168.0.42 Filter 4 Valve 1 8 4 See Filter 1 192.168.0.43 Filter 4 Valve 2 8 4 See Filter 1 192.168.0.44 Filter 4 Valve 3 8 4 See Filter 1 192.168.0.101 VSD 1 28 28 PPO 5 type selected 192.168.0.102 VSD 2 28 28 PPO 5 type selected 192.168.0.103 VSD 3 28 28 PPO 5 type selected 192.168.0.104 VSD 4 28 28 PPO 5 type selected I/O Bytes Total 420 192




7.8.1 Estimated Network load: Summary for calculation: Number of I/O devices: 24 Average Input Bytes per I/O device: 18 (Roundup 420/24) Average Output Bytes per I/O device: 8 (Roundup 192/24) Result: 1.056% Network load




END OF DOCUMENT

Design Standard DS 43-04

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Transcript of Design Standard DS 43-04