I have searched the National Instruments database and the Agilent database and had no luck. It appears that NI provides an instrument driver for the HP 54720A but not the D. In response to your desire to get a LV 5 driver, National Instruments does not supply instrument drivers for versions older that 6i.
I am unfamiliar with the differences between the A and the D, but if you have tried the A driver and it did not work, then they must be significant. I believe you will have to see if Agilent has any instrument drivers developed in LabVIEW for that device.
Colin Christofferson
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