hp34401a and ID query error with a GPIB connection

[diddy]

Hi all,

I am trying to talk to an HP34401a multimeter using Labview 7.0 and VISA 3.5. I get and ID query error when using the Initialize VI from the 34401a library: Error code -107400951 (decimal) or BFFC0011 (hex). I have used the VISA VI "FindResource" and can see all my serial ports, as well as three instruments I have connected via GPIB. So the GPIB seems tp be working OK.

Apparently this may be a problem with the firmware in the 34401a, and its compatibility with the NI instrument driver. If so, what needs to be done to get things functioning?

Many thanks,

Alistair.

[Dennis_Knutson]

You need to find out what the instrument is actually responding with to the *IDN? query. You can do this in MAX or open the HP34401A Initialize function and stick a probe on the VISA Read output in the case statement labeled Query Instrument ID. The VI is expecting the string "34401A" to be in the response. If it is different, you can add the actual string you are getting as another valid response. Also, you are not forced to run the ID query. You can wire a false to the ID Query? input and it will be skipped.

[diddy]

Thanks for the quick response,

The probe on the VISA read output in response to the *IDN? query returns (strangely) the value of the voltage being read by the multimeter. So this eventually generates the ID query error. In the HP34401A Initialize VI, the multimeter shows an error on its screen (and beeps) when the call is made to the HP34401A Control VI (which is meant to place the multimeter in remote mode). However, no error is returned by the error handler in Labview. By the way, the multimeter is already placed in remote mode prior to this call.

regards,


Alistair.

[Dennis_Knutson]

If you are getting a voltage reading instead of the id string, then my guess is that at some point, a measurement was requested but a read of the results was not done so you are getting old data from the buffer. If you turn off the instrument and reset it and then do the *IDN? as the first thing, the instrument should return just the id. If it doesn't then something is a bit wrong with the instrument. When you did a search for instruments in MAX, what did MAX report when it did the *IDN? query?

[diddy]

I had already tried cycling the power on the instrument. I have rechecked it, and the *IDN? query still returns the reading on the multimeter.
MAX recognises that there is a device at address 22 but the response to this query is "The device did not response to a *IDN? query". MAX recognises two SR830 lock-ins that I also have connected via GPIB with no problems.

Alistair.

[diddy]

By the way, I have just tried with a second HP34401A multimeter, and I get the exact same response. This would indicate that it is not a problem with the multimeter I guess?

[Dennis_Knutson]

Or there really is a problem with the firmware in the instruments you have. I have an older 34401A that works perfectly. You could try the same with all other instruments disconnected and see if one of them are causing a problem. If the id query is the only problem, then I don't see what you can do except skip the query or get an update from Agilent. I don't see this as a problem with the GPIB board or the NI software.

[diddy]

OK, I will try and contact Agilent. Thanks a lot for you help in any case...

Alistair.

[testguy666]

I recently had a similar problem in which some of my 34401A DMMs worked perfectly fine with my GPIB interface and others threw an error for ID Query. After going into the I/O menu I discovered the working units' "Language" was set to "SCPI" whereas the DMMs producing errors were set to "HP  3478A".

Setting the devices back to "SCPI" fixed my issue. 

[Luyang]

Hi, I'm having the same problem. When I check the "language" in I/O menu, it is SCPI. But how do you know the producing errors were set to HP 3478A? And How do I set the device back to SCPI?

Thank you,