I am also facing problem with the GPIB ibrd command. I can see that command is sent and it never get the resposne back and it keeps on waiting forever. That makes it to hang.
I have captured the logs using GPIB sniffer
Last command/indication on CMU screen:
Last commands/indications using GPIB sniffer NISpy
READ:SCALar:RXQuality:HACK:EXTended?". Status: completed
GPIB read (ibrd) -- which is not completed (xxxx in ibsta) … GPIB hangs?
Extract from Capture.spy
1432. ibrd(UD15, 0x06146748, 100000 (0x186A0))
Prozess-ID: 0x0000013C Thread-ID: 0x00000638
Starting point: 21:03:33.116
ibsta: 0xXXXX iberr: XX ibcntl: XX(0xXX)
I had a similar problem to the ones described here, my program did hang upon repeated reads or asynchronous reads of larger data blocks (oscilloscope waveform). I finally found that this was due to an USB cable extension I used to connect the USB GPIB interface, which probably randomly messed up the timing of the USB communication. After removing this extension, everything worked fine.