can two gpib hosts communicate on one GPIB bus

[David1024]

I have an application where there is an PCI-GPIB card that controls several programmable power supply units.

Could I add a second GPIB interface (say...USB) and plug into the existing GPIB bus and have the PCI(machineA) and USB(machineB) GPIB hosts talk to one another? Only one GPIB interface would need to talk to/control the Power Supplies. Is this a supported configuration?

[NI-488.2 master]

This is supported. The second GPIB interface must be configured to be not the System Controller. You can do this programatically when bringing the board online like this:

int BoardHandle = ibfind("gpib0");
ibrsc(BoardHandle, 0);

You'll also want to be sure to set the second board at a different PAD than the first board.

Craig A.
National Instruments Engineer

[GPIB_Guru]

You could also use NI-Device on the non-controller interface. NI-Device is a companion API to NI-488.2 that is designed for non-controller implementations. If you hope to make a robust device, this may be easier. If you plan to make a very simple interface, either solution should be satisfactory.