What is the 'Scan for Instruments' sequence for a GPIB-USB-HS+

[RichardY]

I am recreating a GPIB interface for a system. I have a problem getting the GPIB-USB-HS+ to recognise the device when I 'Scan for Instruments'. It seems to occasionally recognises a device and let me start using the NI-VISA tools. When this happens I can then send write and read commands sucessfully.

My question is this, what is the sequence does the system use to scan for devices on the bus?

I have attached a trace of the results that I am getting. It appears to be scanning each primary and seconary address, but I can't see it initiating an *idn? command. When I get a device show up from a scan then it says that it didn't get a response from the "*idn? command sent.

Is there any way of getting the system to only check the primary address that I am using?

[Minions]

There are prior command formats for requesting the identity of an instrument.  I believe that the bus goes out and performs a status poll at each address.  If it obtains a status response, it then will perform the current standard query of:

*IDN?\n

As some instruments do not respond to that, you may need to inquire with one of these prior commands:

ID?\n
U0X\r\n