Eurotherm/ModBus trouble

[RMy]

I am stuck. I communicate with an Eurotherm 2416 controller via ModBus. This works for some hours, then LabView hangs and I have to reboot. I use the Allcomms VI's found on internet. This VI's works perfect with another 2416. I have tried "everything" to solve this. Does anyone have any suggestion what could be wrong and what I should try?

[mikeporter]

When you say it "hangs" what exactly do you mean? Does the system respond at all, or does LV freeze? Where did you get the drivers you are using? I'm not familiar with those, but I'll grab a copy and look at them if you tell me where you got them.

Mike...

[RMy]

"Hangs" - Computer works, but LV is not responding (shows only a white screen) and is not possible to close/shut down. I think the VI's are linked to somewhere at the NI-website, but I attach them together with the VI where I use these drivers. This VI is a sub-VI in a larger application that works fine as long as I dont implement the Eurotherm part.
Actually, I have 4 Eurotherm wired together (RS485) and connected to computer via RS485/RS232 converter. I have tried to use only one controller but LV still "hangs" after some hours. I have tried other communication parameters (baud rate, parity) with same results.

Rune

[mikeporter]

Thinking about your problem last night it occurred to me that the name of the drivers (ALLCOMM) sounded vaguely familiar. And the feeling was confirmed when I saw the drivers you posted. I remember downloading them several years ago and spending a lot of time fixing them. They are horrible code and it would be a gift to the LV community if whoever is hosting them would throw them away and replaced them with something that worked.

In any case, this evening when I get back to my apartment I'll try posting you the drivers I use for Modbus. In the mean time, email me directly. I have had problems in the past with posting large files to the forum and if I have your email address I can send them directly to you if there's any trouble.

Mike...


mlportersr@webtv.net

[mikeporter]

Just tried to post my drivers but the file is too big. Send email me and I'll send them to you directly.

Mike...

mlportersr@webtv.net

[RMy]

Problem solved! First I changed to better "Comms"-VI's. First without further luck, but finally I was able to see where LV hangs. Because I had put the "Comms"-VI inside a while-loop, the serial port was initiated/opened each iteration of while loop. Thats the result of non-critical use of other persons VI as sub-VI... (But, it worked fine on another setup though.) When I placed the serial port initiation before the while loop, everything worked fine.

I am using a 4-port serial board from NI in my setup. In the other setup, the computer serial port is used. Could this have anything to do with?