ORR:OPEN takes a long tme to complete. I used "*OPC?" and "*WAI" to wait for OPEN correctin to finish but to no avail. There is also no timeout setting for the HP424A. Does anyone has a syggestion as to what a user can do to and wait for CORR:OPEN to finish before the Visual Basic code continues?. At this time, it looks like the pause is not long enough and I get a timeout error. Thanks.