Ref: P .ppt (5/24/2014) 1

EUROTHERM

CONTROLS

Profibus

Tim Linnell (Eurotherm Ltd)

Ref: P .ppt (5/24/2014) 2

EUROTHERM

CONTROLS

This Talk

Brief overview of Profibus family

Profibus DP - Where it came from, how it works

Profibus GSD Files

Profibus Slave Operation

Eurotherm GSD File editor

Future

Ref: P .ppt (5/24/2014) 3

EUROTHERM

CONTROLS

Profibus Family

Profibus DP

– Fast transfer of time critical I/O data

– Machine building/Automation ~ 10mS scan time

– „DPV1‟ adds „Acyclic‟ messages and high level data type

definitions

Profibus PA

– DPV1 Messaging + Device Profiles + Intrinsic Safety

– Slower Physical Medium (31.25 kbit/s) with loop power

– Process Applications

Profibus FMS

– „Full‟ Messaging (I/O + non time critical)

– Higher level Communications (PLC <-> PLC)

Ref: P .ppt (5/24/2014) 4

EUROTHERM

CONTROLS

„Traditional‟ PLC Control System

Internal ‘Backplane’

Transfers Input and Output data

between CPU and Modules prior

to PLC scan cycle

Data from modules ‘appears’

in I/O registers in the CPU.

Processed by application

Point to Point wiring to Plant - Essentially 1 wire per signal

Ref: P .ppt (5/24/2014) 5

EUROTHERM

CONTROLS

PLC Control With DP

Internal backplane replaced by external High Speed RS485 cable connected to Scanner Module. I/O data from devices is transferred cyclically - „appears‟ in PLC registers to be processed by application.

Modules replaced by „Devices‟ - I/O or special function

Ref: P .ppt (5/24/2014) 6

EUROTHERM

CONTROLS

Cyclic I/O Data Transfer

Slave Input Data (To PLC)

Slave Output Data (From PLC)

Temperature

Working Setpoint

Loop Output Power

Alarm Status word

PLC Registers

Target Setpoint

Manual Output

Scanner transfers I/O Data from/to PLC once each scan cycle for each slave ~ 10mS cycle

Application uses data from input registers and sets values in output registers

Ref: P .ppt (5/24/2014) 7

EUROTHERM

CONTROLS

General Benefits of using Fieldbuses

Wiring Cost reduction (35 - 40% of total)

Easier maintenance, and flexibility to add new

devices when and where needed

Use „best of breed‟, specialised, devices easily at all

points in the application - reduces load on PLC

Devices located close to point of application and

closely coupled to it

Feedback from smart devices reduces planned

maintenance and allows quality improvement via

SPC etc.

Not limited to modules produced by vendor of PLC

(or PC3000!)

Ref: P .ppt (5/24/2014) 8

EUROTHERM

CONTROLS

DP is popular with users...

Easily understandable - no need to read the spec!

Easily applicable - devices interwork without

problems

Transparent to PLC programmers

Very little ongoing network maintenance

Supported by a very wide range of device and PLC

vendors

DP systems are now being constructed on a very

routine basis without problems - not an R&D

exercise.

Ref: P .ppt (5/24/2014) 9

EUROTHERM

CONTROLS

DP is popular with vendors

Based on a range of Siemens ASICs - easy hardware

implementation for slave devices

Pre-Canned modules available (Siemens, Hilscher,

SST etc) to add DP to products without significant

hardware development

Easy to support - ASICs ensure third party devices

work in a consistent and predictable manner

Result is a healthy proliferation of different kinds of I/O

and specialised devices

Ref: P .ppt (5/24/2014) 10

EUROTHERM

CONTROLS

Why Eurotherm chose Profibus DP

DP is currently the best choice for networking PLCs

with I/O and other devices. Fast, simple, and

available.

DeviceNet is too limited in bandwidth for larger

applications, and third party support not as

comprehensive.

Foundation Fieldbus not widely adopted.

Profibus DP now adopted within Eurotherm as our

main Fieldbus platform.

Ref: P .ppt (5/24/2014) 11

EUROTHERM

CONTROLS

Profibus - Weaknesses.

Limited „acyclic‟ capacity. Not good for SCADA or

large scale file transfers.

Not really plug and play (like DeviceNet)

No pre-defined Function Block library (like FF)

Ref: P .ppt (5/24/2014) 12

EUROTHERM

CONTROLS

Eurotherm‟s Profibus Range

T940

SCADA - PC Cards

Wonderware, Wizcon,

Interlution

subselect.me

OK OK OK OK OK OK OK OK OK OK

2000F PID Controllers

T630 Process Controller

Thyristor Power Controllers

Chart Recorders

AC/DC Drives

2900 e °

CPU

Heat

Tem

p

Inner

Tem

p

Mai

n A

ir

Mai

n F

an

Aux A

ir

Aux F

an

Run

Co

ol

Rai

se

Lo

wer R

ese

t

Ho

ld S

erv

o

Fri

dge Lig

ht

1

Lo

ad

Lig

ht

2

Loop Loop Relay 4 DI/DO 8

2500 Multi-loop

PC3000/PC300 T800

Ref: P .ppt (5/24/2014) 13

EUROTHERM

CONTROLS

GSD1 Files

Define third party devices to Profibus DP network

configuration tools.

Include timing information, supported baud rates,

links to bitmap images, etc.

Include details of I/O Mapping and „Parameterisation‟

Contents downloaded to Slave devices on network

startup

In Eurotherm products, define the set of device

variables transferred over Profibus. Set up using our

„GSD File Editor‟ 1Gerätestammdaten

Ref: P .ppt (5/24/2014) 14

EUROTHERM

CONTROLS

DP Network Configuration

GSD

GSD

GSD

Ref: P .ppt (5/24/2014) 15

EUROTHERM

CONTROLS

DP Slave Operation

Units first „parameterised‟ by Master

– Sends up to 244 bytes of Vendor Specific Data

– Data comes from GSD file

– In Eurotherm devices, defines content of I/O messages

Units then „Configured‟ by Master

– Up to 244 bytes Type and Size data defining I/O

– Data comes from GSD file

Slave enters „Data Exchange‟

– Exits back to parameterisation on timeout

– “Diagnostic” requests made on status change or fatal error

“Diagnostics”

– Not well understood (even by Siemens!)

– Flagged during I/O exchange

– Provide indication of Fatal Device Fault or

– Provide indication of Status (e.g. sensor fail)

Ref: P .ppt (5/24/2014) 16

EUROTHERM

CONTROLS

Profibus DP “Slave State Machine”

“Config Data”from GSD File

“User Parametisation Data ”from GSD File

Ref: P .ppt (5/24/2014) 17

EUROTHERM

CONTROLS

Why Use a GSD Editor?

Profibus designed for simple bulk I/O devices (e.g.

16 words I + 0)

Our products are much more complex (500-3000

parameters).

Impossible to choose a universal subset for I/O, and

wasteful of bandwidth to transfer unnecessary

variables.

Best approach to allow I/O mapping selection by

users on a per application basis

Ref: P .ppt (5/24/2014) 18

EUROTHERM

CONTROLS

Problems

GSD file provides user data. Obvious place to define

I/O transfer, and values from file may be changed by

user using network configuration tool

However data type definitions are also in the GSD

file, and closely coupled to I/O definition.

Data type definitions are not usually changeable

using the network configuration tool

Solution Chosen - Create a GSD Editor tool to define

I/O transfer in users’s terms, and manage type

definitions automatically...

Ref: P .ppt (5/24/2014) 19

EUROTHERM

CONTROLS

Eurotherm GSD File Editor

Creates Custom „GSD‟ file for use by network configurators

Ref: P .ppt (5/24/2014) 20

EUROTHERM

CONTROLS

Why Use the GSD File editor

Very easy to use - drag and drop interface

Allows optimum use of network „bandwidth‟ - only

transfer the variables you need

Permits very flexible use of devices - no need for a

„lowest common denominator‟ mapping

Avoids manual editing of GSD file employed by

other vendors - error prone and complicated

Build up a library of GSD files for different

applications

Use the PLC to „wire‟ between device variables for

complex control strategies

„Web‟ button for latest hints and tips on-line

Ref: P .ppt (5/24/2014) 21

EUROTHERM

CONTROLS

Demand Data

Cyclic Data interchange is great, but…

– Relentlessly overwrites values set via the front panel of the

instrument (though this can be overcome with sequence logic)

– Allows access to a limited number of device variables

„Demand Data‟ provided to solve this problem

– Uses 4 words in the input and output areas

– Allows read or write access to all device variables „on demand‟

– Uses a simple „mailbox‟ system, easily programmable using a PLC

sequence program

– Switched on or off by the GSD File Editor

– Supported by specialised PC3000 Function Blocks

DPV1 provides “proper” acyclic messaging (currently 2500 E-

Suite only)

Ref: P .ppt (5/24/2014) 22

EUROTHERM

CONTROLS

Future

Profibus group pushing ProfiNet (Profibus on

Ethernet)

Various other developments (Plug and Play,

ProfiSafe, Expansion of Profibus PA).

May be better long term bets for higher level

Ethernet protocols (e.g. FF)

Ref: P .ppt (5/24/2014) 23

EUROTHERM

CONTROLS

Conclusion

Profibus DP allows easy interconnection of

Eurotherm and third party devices

Good for small scale “Machine Building” networks

Less good as a SCADA network

GSD file editor and „Demand Data‟ allow great

flexibility of operation with Eurotherm slaves.