Reading process value from Eurotherm 2580 DIN Rail Controller using Labview

[tryten]

Hello! 
I have two identical 2580 Eurotherm DIN Rail Controllers, which have different modules(AI,AO etc) connected to their racks. These two controllers are connected to my PC via 2-wired RS485 cable (Modbus) to a MOXA Nport 5430 server with 4 RS485 ports, which from there is connected to the PC via ethernet(TCP/IP). I have used the Nport Windows Driver Manager to map the 4 COM ports into my computer. The Eurotherm specific program (iTools) used to configure the controllers, read out addresses, values etc for different process parameters works just fine. The controllers use baud rate 19200, no parity, 1 stop bit, and this I have also configured in VISA and for the Nport server.

I am now trying to read the process values and write setpoint values to the controllers using Labview 2017. For now I am trying to simply read a temperature measurement (at address 6455) I have in the first Eurotherm controller , which is connected to the Nport at port 2 (COM 3 in my computer/Labview). I would like some help on how I can do this? What interface/libraries should I use in Labview? Modbus library? VISA? How can I access address 6455 in the Eurotherm from Labview, what is the command used for this? An example VI of a similar case would be extremely helpful.

I havent found any NI drivers specific for my Eurotherm controller series. Also, the manuals for the Eurotherm controller does not describe the command set and protocols for reading and writing to its registers, so not much help there. I did briefly attempt to use the Modbus library 1.1.5.39, but havent succeeded so far. Also, I tried to use the VISA test panel to read the controller IDs, and got the error message VISA:  "(Hex 0xBFFF0015) Timeout expired before operation completed."

Thanks in advance!

[tryten]

I now managed to successfully read process values from my PLS, using the Modbus 1.1.5.39 library! So case solved there 🙂

However, I have a question related to this: 

In my project I have a main.vi and subVIs inserted into it. The subVIs will need to indicate process values and write to output modules in the PLS. I am displaying the front panels of the subVIs in a tab control in main.vi. How should I set up the modbus communication ports COM3 and COM4 to my two controller modules? In main.vi or in a subVI, and use local variables to send data between subVIs? My application is multithreaded, so I need to be able to read and write from the different subVIs independently.

Thanks in advance!