This instrument is moderately early in the development of HPIB programming so the generic HPIB commands from later developments in the HPIB languages are not recognized because they are not in the 3478A command set in its PROM.

If you want more modern HPIB programming then I would suggest the 34401A DMM (6.5 digits) or later, a better, more capable DMM than the 3478A (5.5 digits).

Don Bitters