VISA Code to read conductivity with an eDAQ EPU357 Isopod - error -1073807194

[Mike-ANL]

I'm trying to develop some Labview 2019 code to read and log conductivity with an eDAQ EPU357 probe and one of their Isopods, which connects to the PC with a USB port.  The code sends a text string as a command to the device which then returns a text string result.  They have sample code available but claim to have never tested the code.  I've simplified the code a bit and am trying to use it to collect data about once per second.  I have one VI that just initializes the USB port for baud rate, etc which is uploaded below.  When I attempt to run that I get this error message:

"Error opening resource:
ASRL3::INSTR

VISA: (Hex 0xBFFF0072) The resource is valid, but VISA cannot currently access it."

Can someone suggest a fix or something for me to check out?

I've run TeraTerm with the device and get the expected results.  I've closed down TeraTerm and used the VISA Clear coomand to (presumably) reset the USB port before running the LabView port initialization VI that gives me the above error message.

I used MAX to determine the port address (COM3) and have tried to open a VISA test panel but get the same error message:

"

Error opening resource:
ASRL3::INSTR

VISA: (Hex 0xBFFF0072) The resource is valid, but VISA cannot currently access it."

So far as I can tell nothing else is trying to use the port when I get the errors with my Initialize routine or attempt to run the VISA test panel.

[rolfk]

This error typically occures when the port is already open by a different application. Windows does not allow sharing of serial ports between processes.

[Mike-ANL]

Thanks Rolf.  I could have sworn I had checked to make sure no other apps were accessing that USB port while trying to run the VI code but will try again.

Are there any utilities in LV or Windows that can tell me if something is using a USB port?

Mike

[rolfk · Accepted solution]

LabVIEW definitely not. On Windows level you might be able to find something in the famous Sysinternal tools. It's basically kernel level stuff and that isn't easy to get information for from user space level.