"Addressed to Talk with Nothing to Say"

[RayFarmer]

The trouble is this instrument doesn't understand the Query comment of *idn? which is sent by MAX. This instrument requires IDN? (not the missing * ).

If you try sending the IDN? and then do a read you will get back the expected query string.

[DIAOS]

Same situation here with an old Agilent 8753ES. It kept saying "Addressed to Talk with Nothing to Say" to every command I sent. Finally I found out that I'm using the wrong GPIB address. The "Scan for instruments" function in MAX returned a GPIB address of 17 for the VNA. The VNA instrument was using 16, 17 was for the VNA's display. Everything works fine once I changed the instrument address to 17.