AT-GPIB hangs after 2-3 reads from a HP oscilloscope. any ideas??

[karsten]

I am trying to take Vpp readings from a HP 54710A oscilloscope. I can get 3 readings to come back ok, but communications always hangs on the 4th attempt, forcing me to power cycle the scope and ctrl+alt+delete out of my app.

i'm writing it in VB using a NI AT-GPIB under W98 with the correct drivers, etc. I try also to communicate directly via the 32bit driver window that lets me enter commands directly to the driver, with the same results. The commands i'm using are:

ibwrt ":measure:vpp;results?"
ibrd 12

it works GREAT for 2-3 reads, then just hangs the system completely. i am initializing the system with ibdev and system header off prior to use. Any ideas?? i'm complet
ely stumped. thanks a bunch --karsten. karst@iastate.edu

[Ryan_M]

Do you get better results if you readdress the bus before each write/read? There should be NO difference between one write/read and the next unless there is an external source such as another GPIB application running, another instrument on the bus or the current instrument generating an error or getting incorrectly set. Readdressing the bus may give the instrument time to catch up to the controll if it is an older slower model and it will assure the process that the correct instruments are addressed to talk and listen.