Back-to-back GPIB-USB-HS+ to link two PCs.

[scott613]

Has anyone ever heard of using back-to-back GPIB-USB-HS+ (with an adapter in between) to connect two PCs? I am trying to automate a power supply for a test. The power supply's manufacturer says that in order to accomplish this I must run the LabVIEW VI on a different PC than the one running their control software. I'm supposed be able to link the two PCs with these back-to-back GPIB connectors and the control PC will appear to the VI's PC as a GPIB instrument as long as their control software is running. However, when I try to find the control PC (as a GPIB instrument) on the VI PC using NI MAX I see the GPIB-USB-HS+ in the device tree but MAX says it can't find any instruments. I put a known good GPIB instrument on the bus to verify that the USB connector is working, and I find it with no trouble. The manufacturer says it's supposed to work but so far not for me.

[Albert.Geven]

Hi

I understand that the powersupply is also controlled by software from the manufacturer. Probably via the GPIB connector. 

If that software is running and controlling the power supply how do you know you may control it via the other connector. Maybe it is better to understand what the other program is doing and rdo that in LabVIEW.

Connecting an extra master on the bus takes a lot of effort to stop the original master if even possible!

Maybe easier to ask the power supliers program to halt and release the bus.

Just a few ideas when reading your question.

[scott613]

Hi Albert

Thank you for the reply.

Actually, the power supply connects to the control PC (the PC with the manufacturer's SW) through an Ethernet to fiber optic connection at 192.168.10.xxx.  According to the PS builder I must have their software running on the control PC in order to use GPIB on the second PC.

I was under the same impression as you that if I connect a NI GPIB-USB-HS+ to a PC then it will be seen on the bus as a master so if I have two of these connectors then I have two masters and no instrument. When I run MAX on the second PC and try to find a GPIB instrument MAX says it found none. They say that the control PC appears as an instrument on GPIB at address 8 to the second PC but so far that hasn't happened.

I've never heard of anything like this and was just curious if anyone has.

They swear this has been done by some of their other customers.

[Albert.Geven]

So, they claim to be able to act as a slave on gpib. Maybe when you insert a gpib interface in the control pc. But also maybe they have an ethernet possibility to communicate with the control program or any other bus, even a virtual ethernet connection from within the same pc could be possible, even a dll call. But I would not use 2 gpib cards.