Labview GPIB-USB-HS and Network Analyzer

[BTC_Admin]

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@MicrowaveEgr wrote:

Thank you for your reply; I am using GPIB-HS-USB that connects from the VNA to the computer. It was working fine, then stopped in the middle of a measurement. We have had some issues before, but typically turning off the VNA and computer, re-calibrating the VNA and then connecting the USB cable to the computer would generally work, but now that does not.

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Uggh, my bad, I should have read your subject line to know what GPIB device you were using.

Since your device is USB based, have you tried to take USB bus itself out of the checklist of problems? I say that because I have seen some instances where a badly made USB driver for some random device ended up locking every USB port!  It would be very easy to test - when you don't see your GPIB-HS-USB device on NI-MAX, check to see if it exists on Control Panel (assuming you're using Windows, on MacOS you can check it under System Information->USB). If the device doesn't exist there either, make sure that USB is working fine by plugging in a USB stick on another port and see if it comes up on Windows Explorer.  If it comes up fine, try disconnecting just the USB side of your GPIG-HS-USB/wait 10 seconds/connect it back... and then check on Control Panel to see if it comes up.

The cable that comes with GPIB-USB-HS is quite sturdy, if it is connection problem then most likely on USB connector side on the computer (which would be easily fixed by simply plugging in the cable to another port).

If your device is visible by Control Panel at all time, problem is somewhere in NI-MAX/NI drivers installation/etc. You could remove the configuration file and restart NI-MAX to see if it makes a difference.  (Have you tried the device on a different computer? Might be worth a try rather than spending hours on figuring out the unknown. Please also start with connecting only one device (your VNA) on the GPIB bus.)

-DP

[MicrowaveEgr]

Thank you for the reply; the GPIB-HS-USB is found in the Device Manager whenever it is connected, but nothing else shows up (I don't know if the Instrument is supposed to show up in there or not.)

When I run NI MAX, sometimes it detects the device when I click on 'Scan for Instruments'; it will show a device with PAD of 16, and it will list of the name of the VNA in the Description area, but I still cannot run the program, even when/if it detects it. Other times, only a device of PAD 17 will show up, which is not the address of the device that we need. The GPIB-HS-USB device always seems to get the power that it needs (the READY LED is on when it's connected) so that does not seem to be an issue.

Are there any other things that I can check?

Thank you.

[Dennis_Knutson]

It sounds like a problem with the instrument, to me. You should never see an instrument with an address that does not exist. Can you try a different instrument? Do you have another GPIB controller that you could try?

[MicrowaveEgr]

There was someone else in our lab who used the GPIB cable with a different instrument, and it seemed to work fine for them, although I do not think that instrument is in our lab any more.

My guess, too, is that it is the instrument that I am currently using that is the problem, but the fact that sometimes it works great and other times it just doesn't work doesn't make sense to me. And I've tried it with other computers, and that does not seem to fix the problem.

[MicrowaveEgr]

When I try and use the NI-488.2 Communicator, that seems to work fine; if I type "*IDN?" it will write and read, and I can also see the LED's on the front toggling, like they should.

However, when this works, the Labview code still does not function. I still get the "The Connection for the given session has been lost." error.

One thing that I did notice in NI Max, in order to detect the VNA using 'Find Instruments', I have to set the PAD to something other than 16 (either 0 or 17, usually) for it to detect the VNA at PAD of 16. Is that an error as well? Previously, when I had the PAD set to 16, it was able to detect the VNA at the address of 16.