How do I use the NI-488.2 software to talk to an instrument's system bus?

[Larry Martell]

I am trying to interface to an HP8510C, which has a system bus with
other instruments connected to it. The docs for the 8510 say to control
the instruments on the system bus you use a "pass-thru" mode by first
sending a message over the GBIP to the 8510 to select the instrument on
the system bus you want to talk to (using the "ADDRPASS" command), then
next "send a normal output command addressed to the system bus, as if
the device were connected to the computer directly." My problem is that
don't know how to send a message addressed to the system bus.

The 8510 has a GPIB address of 16, the system bus has an address of 1,
and the instrument on the system bus that I want to control has a
system bus address of 19. To communicate over the GPIB with the 8510, I
do the normal:

handle = ibdev(16, ...);
ibwrt(handle,buf, size);
ibrd(handle, buf, size);

To put the 8510 in pass-thru mode, and specify that I want to talk to
the device at address 19, I do:

ibwrt(handle, "ADDRPASS 19;", size);

Now according to the 8510 manual, in order to talk to the device at 19,
the next thing I am supposed to do is send a message "over the GPIB bus
that is addressed to the system bus address". How do I do that with
NI-488.2?

TIA!
-larry

[ScottPageUSMC]

I am currently onsite and away from my code that addresses your problem to a "T".  Normally, you send the pass-thru command to the 8510, the 8510 is then in pass-thru mode, so any following commands to it will be written to the device you are "passing-thru" to.

In other words, send the "pass-thru" command to the 8510 to tell it that the next commands will be for an instrument at the specified pass-thru address, then send the commands to the device you want to talk to on the 8510 "system" bus.

I have source code for this in my lab, I will try to download it while I am onsite.  If I can't get it, I will use the 8753D I have here to emulate the same method.