Restarting a given COM port

[LTBALAZS]

Hi,

I keep loosing communication with an instrument randomly. Sometimes data acquisition works trouble free for days , sometimes for a couple of hours. After I've lost the communication i must restart both the PC and the instrument.

Can i force a specific COM port to restart run-time in labview? I am using an RS232 DB9 connector with shielded cable of length 1 meter.

Have you got any ideas how to solve this technical issue?

Kind regards,

Balázs

[LucianM]

What do you mean by restarting the COM port? You can close it by calling VISA Close and then open/configure it again. Do you keep the port open all the time while the program is running? Any error when the communication is lost?

[LTBALAZS]

Yes, opening and configuring it again does not help. Please visit this topic to see the errors.
https://forums.ni.com/t5/LabVIEW/Communication-stucks-with-Ketihley-2700-data-logger/td-p/4021341

[Eric1977]

At any point does your program go into a idle state for a period of time? Are you using a serial to USB converter?

It would help us if you uploaded your VI too.

[Frozen · Accepted solution]

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@LTBALAZS wrote:

 After I've lost the communication i must restart both the PC and the instrument.

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Yikes! Assuming that the SW is written correctly, this might indicate a ground loop or ESD problem. Or maybe a power problem? Have you try using a laptop?

Another thing to try is to throw away the Keithley supplied instrument drivers and code up your own.

BTW. It is very hard to troubleshoot intermittent problems like yours.

[LTBALAZS]

Hi, it was ground loop problem.