Instrument Control (GPIB, Serial, VISA, IVI)

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two GPIB controller setup

I have a few instruments all connected to one GPIB, 488.2 bus controlled by one computer, Windows 10, updated, etc. One of the instruments is another computer with a PCIe-GPIB card. That computer does plenty of work, but the data transfer between the two is minimal and one way, just a few short commands. The data transfer is managed by proprietary software that came with the system, so when it's all working, the short commands cause it to do things.

 

While this usually works, intermittently it doesn't. NI Max on each computer sees all the instruments on the bus except the other computer, simultaneously. If I disconnect everything else, and run the cable from one computer to the other, neither see any instruments. The software, then, would seem to be irrelevant. I've restarted both systems, reset, refreshed, scanned, and knocked my head against the concrete. It seems these two instruments just don't want to talk to each other! What have I missed?

 

computer 1 (desired system controller): GPIB interface ID GPIB0, primary address 0, System Controller true, enable autopolling true. USB-GPIB interface, v18.5.0f0

 

computer 2 (desired slave): GPIB interface ID GPIB1 (or GPIB0), primary address 1, system controller false, enable autopolling false. Windows 7, PCIe-GPIB, v18.5.0f0.

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Could you please provide a better diagram of how the cabling is done?

 

Are you trying to connect two GPIB controllers to the same GPIB bus because you want both systems to access the same instrument?

-Santhosh
Semiconductor Validation & Production Test
Soliton Technologies
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Ok, I missed the subject, now it makes sense what you're trying to achieve.

 

So, the GPIB protocol states that the bus can have more than one controller but only once has to be active at a time. It looks like in your case, both controllers are active at the same time causing issues.

-Santhosh
Semiconductor Validation & Production Test
Soliton Technologies
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Hi,

Yes, it would seem that way. How do I get the other one to shut up? Setting the system controller check box to false (unchecked) isn't sufficient? It's like I need to lobotomize the thing, as need it to respond to commands when spoken to, and nothing more. Maybe I missed something in the proper sequence of settings and restarts (e.g. turn power off to the computer, then turn it back on)?

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You might have to configure this explicitly for each GPIB card and make sure only one is a set to a system controller.

santo_13_0-1617849172077.png

 

-Santhosh
Semiconductor Validation & Production Test
Soliton Technologies
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And then magically it works, when I disconnect and reconnect the USB-GPIB plug from the desired SC computer. Now, the controller can "see" the 2nd computer just fine. Not sure where that instruction was in the NI documentation. 

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