howto: labview retrieve hp34970a / 34901 mux module thermocouple data

[scott-e]

I have labview talking to a hp34970a with it's generic driver. I'm reading thermocouple data from 12 different channels via a 34901 20 module.

The problem is I have to take 12 channel read requests when I would like to retrieve this information with a "scan list" command where it readings all 12 TC channels with one scan request.

Anyone have information on how to use scpi or similar program commands to get labview to use a scan type of command?

There seems to be many similar commands but I want to do a very simple snapshot reading of the 12 thermocouples.

If anyone has some sample programs, moocho appreciate.

Thanks!


I would like to incorperate a "scan" command

[Alan_L]

Scott-e,

The LabVIEW "instrument drivers" are helpful in that they abstract away sending specific commands to your instrumentation. Underlying these "drivers" are calls to the VISA library. These calls write commands and read responses from your HP Instrument.

If this "scan list" functionality is not provided with the instrument driver, it still may be possible. Please review your instrument's manual - specifically the pages that deal with command formatting. There may be an instruction that you can issue with a VISA Write that will tell the HP unit to return one data set containing all 12 measurements. That data can then be retrieved with a VISA Read (given your instrument has had enough time to compile results after the write has been issued).

If yo
u're using LabVIEW 7 Express you can use the Instrument I/O Assistant to quickly generate a VI that will send a command, read the response, and parse the results into the 12 readings. (called Query & Parse)

I hope this helps. Happy programming!

Alan
Applications Engineer
National Instruments




PS. Great screen name!