Visa open, write, close

[BertMcMahan]

Thanks for the info! I would have assumed that trying to read a branched/closed VISA session would have resulted in an "invalid reference" error. Your explanation makes sense- thank you for typing it out.

[Ben]

VISA open vs close

There is an option to automatically close VISA session on exit that implies they stay open.

Sea G-Story time!

Spoiler

I was handed an application that used multiple instruments that were all VISA based, a Temp Chamber that used VISA to talk Modbus which were all used to calibrate instruments that were themselves serial based.

Between the "automatic discovery" of DUTs to calibrate and new instruments being added to the game, there were times when an instruments was discovered but then found not to be a DUT... Or Windows deciding a port was idle too long and had to be closed to save the planet...

I ended up having to add  logic to detect if there was a VISA write error (Writing to a serial port has to be one of the safest operations if thing don't mess with closing ports) and if so re-open the port.

I did not develop the original code and I passed it off to a rookie as quickly as I could!

Ben