Attached is an NI-SPY file of the "Agilent 34401a read multiple measurements.vi" example ran with a USB-GPIB-HS. You should find all the information you need there.
you should be able to open it if NI-SPY is installed on your computer. NI-SPY is installed with NI-VISA. I've attached a screenshot of the file in case you do not have this software.