Errors 410 and 420 with Agilent 34970A

[Arrington]

Hello, all. I'm helping a colleague with an application measuring ten channels each of temperature, frequency, and current using an Agilent 34970A DAQ switch (GPIB) and LabVIEW 7. We keep getting errors 410 and 420 from the switch. When the error occurs, then the switch doesn't report all 30 pieces of data. I'm looking for ways to a) clear the error; and b) prevent the errors.
Thanks in advance,
-Dan A

[Dennis_Knutson]

According to the manual, 410 is Query Interupted and 420 is Query Unterminated. The first can happen when you send a query but there is still data in the output buffer. If you've requested a certain number of bytes during a read, you probably need to increase that number in order to sure that all data is retrieved. A Device clear command will clear the error. Query Unterminated happens when the instrument is addressed to talk but there is no command pending that will place data in the buffer. The example in the manual cites sending a CONFIG command which doesn't generate data and then doing a read.

Are you using the drivr from NI or have you written your own?

[Arrington]

Thank you, Mr Knutson. I don't believe we're specifying any particular number of bytes, unless that's specified in the defaults. Where can I find the Device clear command you mention? And to which manual are you referring -- LabVIEW, or Agilent (or other)? We're using the NI driver.

[Dennis_Knutson]

Try the VISA CLR function on the Instrument I/O>VISA palette. But you might want to look through the subVIs that return a reading and increase the expected byte counts for the VISA Reads. The driver is pretty good but that doesn't mean that there isn't a bug or two that will show up when the instrument is being used in a manner that wasn't tested by NI. Usually, specifying a much larger number for expected bytes does not present a problem because the read will terminate anyway on getting EOI.

The error codes are in the Agilent manual.