Try the VISA CLR function on the Instrument I/O>VISA palette. But you might want to look through the subVIs that return a reading and increase the expected byte counts for the VISA Reads. The driver is pretty good but that doesn't mean that there isn't a bug or two that will show up when the instrument is being used in a manner that wasn't tested by NI. Usually, specifying a much larger number for expected bytes does not present a problem because the read will terminate anyway on getting EOI.
The error codes are in the Agilent manual.
