GPIB-USB-HS MAV Never set in status byte

[rmatlin]

I recently purchased a NI GPIB-USB-HS device and have connected it to an Aeroflex 4403 and a GW Instek power supply. I can never see the MAV bit set to a 1 in the status byte. Should this device support that? I have software I am trying to use that looks at the MAV bit. I have done this using GPIB PC controller cards but have never used the USB controller.

[D-Cubed]

Hi rmatlin, 

Have you tried to read when only one device is connected?  This may have to do with automatic serial polling.  

How are you reading from the GPIB devices?

Warm Regards,

[rmatlin]

I had tried turning off the auto-polling but still no MAV. Believe it or not, I took both instruments over to another system using the GPIB-USB-HS but with different instruments and confirmed that the other instruemtns set the MAV to 1 and my GPIB-USB-HS was showing me the MAV at 1. When I tried my two instruments neither one set the MAV to 1. I talked to one of the manufacturers and he confirmed that the instrument does not set MAV to 1 when data is available in the output buffer. So much for "standard".