Problem with Modbus communication

[IanLloyd]

I am trying to control an environmental chamber using Modbus over serial.

The application works fine for a while. At some point it just stops responding you can't write a new set point and it doesn't read the set points and actual values.

When you click exit you get the vi resetting box that sits there until you use task manager to close it.

I have run the application whilst logging the output to NI Trace and attached the file.

I have never looked at one of these files before but I can't see anything different at the point it stopped at 08:56

I hope that somebody who knows more about these files can see something to point me in the right direction.

I am using the Plasmionique Modbus Master v1.3.6.1 by Plasmionique Inc from VI package manager

[LVNinja]

Hi 

I wasn't able to open the Vi file, i'm using version 2020. 

Does your vi opens and closes the Modbus library all the time ? 

I noticed some viClose occurences on the trace file. Is it possible that the driver is closed and then the program asks to execute a task with the driver closed  ? 

[IanLloyd]

Thanks for looking at this.

I have attached the vi saved for version 2020

I believe I only close the modbus library after the press of the stop button.

[LVNinja]

Thank you for sharing your code. 

my suggestion is to identify what side is having issues, on the computer side or in the instrument side. 

Try increasing the wait time from 1000 ms to a larger number to evaluate if the module needs more time whne responding to read register requests. 

check the documentation of the MODBUS device to see if there is any limitations on time to respond, buffer, of the communication bus etc.