Temperature Controller

[Rewire]

I have been asked to connect 14 Temperature controllers (Eurotherm 94C) with wonderware. The original concept was with modicon PLC (984). The PLC has been ripped out and a ALLEN bradley PLC (5/04) is being used to replace this. There is also a Xycom touchscreen running Wonderware. I would like to be able to communicate directely to the instruments via Wonderware but I believe that this cannot work. Am i correct in that i need to use a Allen Bradley Basic Module and set up a RS-485 network for the controllers and then use the processor port as a route to Wonderware. Or is there something out there that will allow me to by-pass the AB basic module and talk directely to wonderware. I do not believe that RSView32 would offer a better mouse trap. All we want to do is to be able to duplicate the temperature controller on the Xycom screen. The data that we would be interested in would be to monitor the controller status and temperature preset and actual.Any dialog would be appreciated with regards to communication protocol.

 

[artecerv]

The general set up is to use PLC’s to concentrate I/P’s and O/P’s and serve as interface to field information. The HMI/SCADA should interface to these controllers and access tags (read & write) in their memory. I don’t know much about Wonderware but what I have just said apply to most of the HMI/SCADA softwares I know.

In my humble opinion use the BASIC module to create a RS-485 multi-drop network seems to be the way to go (I assume that you have investigated other communication options like: Profi-bus, Modbus RTU, Modbus TCP/IP or DeviceNet). The data can be stored in REAL or ASCII registers (accesses by the Wonderware).

The only draw back of using the BASIC module is that you will end programming the whole communication protocol (whatever it is) and because of that extensive testing is recommended.

Have a happy and safe New Year.

Regards,

 

[NWBeaver]

Rewire,

Here are my thoughts on the subject.

First, I did a quick check on the Eurotherm 94C specs, and it appears that they use RS422 and perhaps the Modbus protocol.

It seems to me that Wonderware should be able to function as a Modbus master and talk directly to each of the Eurotherms as a slave device. There are some limitations to RS422 though, so it might be worth considering using Ethernet Serial Servers to allow the RS422 devices to appear on an ethernet LAN, assuming your system has ethernet capabilities. I would talk to Wonderware rep, since it sounds like you really don't want to have to go the PLC route.

If you were to go the PLC route, I would take a look at the communication modules made by ProSoft. They make a wide variety of modules for different protocols, such as Modbus or ASCII. The InRAX series of modules are made to fit in a PLC chasis. I have used one for ControlLogix, with good results.

See

http://www.prosoft-technology.com/

 

[danw2]

Wonderware is an HMI program. It can have a Modbus driver (drivers are usually optional) and Wonderware acts as a Modbus master.

The 94C probably talks Modbus, which means that Wonderware can probably talk directly to the controllers, all on one serial link.

There's another simple option, since you just want to "create the controller faceplates on the screen".

An alternative HMI program, Specview, puts up Honeywell controller faceplates and even auto recognizes the controllers on the serial link.

Eurotherm is listed on Specview's site as a compatible device. I'd check and make sure that the Eurotherm faceplate is part of the package. Specview runs on any PC, even older Win 98 boxes.

 

[Rewire]

I would like to thank everyone with this thread, I spent a couple of days playing with basic and a AB basic module, it seams like a step backwards, possibilities are there though. My second response was the most useful, as was the third. I played with the modbus drivers and i am now able to see the Eurotherm instruments on Com3 (we bought a second RS232 card, there is a 422 converter behind this talking to the instruments). The modbus driver works great the detailing of the Modicon registers is kind of weak though. my holding registers in Wonderware are 40001 to 40100 perhaps more. I am now trying to toggle individual bits but it appears to be a hit and miss thing. Has anyone ever mapped out the bits (besides the Eurotherms modbus (Jbus) booklet).

I would highly recommend that the wiring be checked we found that the eurotherm 422 connections are reversed and this is mentioned in a help file with in a program from Eurotherm. After hours of trying with Wonderware to communicate, I downloaded a program called Eurotherm Sampler Version 2.0 and this program basically pointed to the error in wiring of the instrument.

I would like to be able to preset the temperature in the instrument. I can read all parameters but I am having difficulties with the Modicon registers.

Any help with how to manipulate the Modicon registers would be usefull to me.