Ref: P.ppt (6/6/2014) 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 (6/6/2014) 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 (6/6/2014) 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 (6/6/2014) 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 (6/6/2014) 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 (6/6/2014) 7 EUROTHERM CONTROLS General Benefits of using Fieldbuses Wiring Cost reduction ( % 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 (6/6/2014) 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 (6/6/2014) 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 (6/6/2014) 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 (6/6/2014) 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 (6/6/2014) 12 EUROTHERM CONTROLS Eurotherms Profibus Range T940 SCADA - PC Cards Wonderware, Wizcon, Interlution 2000F PID Controllers T630 Process Controller Thyristor Power Controllers Chart Recorders AC/DC Drives 2900 ° CPU Heat Temp Inner Temp Main Air Main FanAux Air Aux Fan Run Cool Raise Lower Reset Hold Servo Fridge Light 1 Load Light 2 Loop Relay 4DI/DO Multi-loop PC3000/PC300 T800
Ref: P.ppt (6/6/2014) 13 EUROTHERM CONTROLS GSD 1 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 1 Gerätestammdaten
Ref: P.ppt (6/6/2014) 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 (6/6/2014) 16 EUROTHERM CONTROLS Profibus DP Slave State Machine Config Datafrom GSD File User Parametisation Data from GSD File
Ref: P.ppt (6/6/2014) 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 ( 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 (6/6/2014) 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 userss terms, and manage type definitions automatically...
Ref: P.ppt (6/6/2014) 19 EUROTHERM CONTROLS Eurotherm GSD File Editor Creates Custom GSD file for use by network configurators
Ref: P.ppt (6/6/2014) 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 (6/6/2014) 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 (6/6/2014) 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 (6/6/2014) 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.