query unterminated

[ayana_from_gatech]

Hello,

I am using E4407B by Agilent and I am getting the error: "Query Unterminated" on my device when I send a command as simple as *IDN?  This has not always been the case, I have run several LabView programs on it.  What should I do to troubleshoot the instrument?

[BerkO]

Hello Ayana,

Could you please be more specific about the problem?

Are you using the LabVIEW plug and play drivers?

What is the firmware version that you are running on the instrument?

Are you getting the error when using the LabVIEW driver or does that happen when you manually send the commands via MAX?

Please let us know so that we can help you further.

[ayana]

Yes, I am using plug and play drivers.  I am using MAX 4.2.0.3001.  And my instrument's firmware is A.14.00.  I am getting the error when I manually send the command using MAX.

Thanx!

[BerkO]

You could try updating the firmware to the latest version which is 14.04. 

However if the issue doesn't go away, it probably is something that agilent would be able to answer better.

Does any other command work?

[GPIB_Guru]

Do you get an answer in spite of the error? Query Unterminated error comes from the Message Exchange State Machine in an IEEE 488.2 device and indicates that you sent a query (message requesting an answer) to the box without a valid IEEE 488.2 terminator and then tried to read from it. A valid terminator would be a GPIB END or and EOS character. If you can get an NI Spy capture it may be helpful to see if anything looks weird (like a call to disable termination).

[ayana]

I updated the firmware, I spoke with Agilent.  They insisted that it cannot be a problem with the instrument - that it must be an error in MAX (even though I was sending the simple command: *IDN?), so I used their IO libraries instead.  I got the same error.  When I told them that, they claimed that it  must be a problem with my GPIB/USB converter.
And no other command works.  When I send the reset command, it says invalid character.

[GPIB_Guru]

Do you have more than one GPIB controller? It could be a bad cable or bad connection... Something so that the string you are sending to the device is not the one that is received. If you have two controllers, you could connect them together to see if they communicate by themselves. If so, then it is probably an instrument issue where the connection could be broken or something to that the data you send is not what it receives.

[ayana]

HI,

Thank you all so much for your responses.  I used two different cables.  One is on a daisy chain with other instruments, the other was just connected directly to the USB port.  Also, I tried other instruments on the same cables and the communication was fine.  How do I connect the controllers together?

[GPIB_Guru]

I would say that if this controller can talk to other devices, than the information that you are trying to generate is properly being generated. I would say that this indicates that you are sending the correct information and the device is not receiving the correct information, which leads me to believe that there is a problem with the device.

That is a terrible answer since I am not a big fan of "pointing fingers", but to me that seems like the only logical conclusion.

You could look at the connector on the device to make sure it is keyed (normally gpib connectors are shaped like a trapezoid to make sure the cable can only connect one way). I have seen some instruments tht don't do that and the cable could be then put on upside down. I think this is highly unlikely. You can look at the connector on the instrument to make sure all of the leads are clean and free of obstruction. My basic philosophy is that the data you are sending is not making it to the device for some reason.

[ayana]

It is definately connected correctly.  I agree with you; I suspect that it is the instrument.  I just wanted to make sure since Agilent is so certain it is not the instrument.  Thank you again for all your help.