Could a long delay (~30 mins) between the opening of a VISA port and the first Visa Read called on it cause an error?

[cgiustini1]

Hi,

In my application, I am reading data from a VISA device that is communicating with my unit under test. Here is the sequence of events:

-unit under test powered on

-VISA port opened

-wait for trigger

-unit under test powered off

-wait thirty minutes

-unit under test powered on

-continuously read from device with VISA read

-when test ends, VISA port is closed and unit under test is powered off

Sporadically (and usually at the worst possible moment), the first VISA read performed returns an error that ruins the rest of the test. Sometimes it is buffer overrun (error code -1073807252) and today it was I/O error (error code -1073807298). Does anyone know if that thirty minute wait could be causing any problems? They seem to happen more frequently when I run this particular test.

Thanks,

Carlo

 

[crossrulz]

Are you using a USB-to-Serial adapter?  If so, it is likely the USB hub cutting power to your adapter after so much inactivity.  This is a power saving feature.  You can change your hub power settings in the device manager.

If it is a serial port on the motherboard or a PCI, then I wouldn't expect the down time to be a problem.

Are you doing anything with the port during the 30 minutes wait?