Error when running VI to acquire data from multiple channels

[laeral]

Hello there, I am currently trying to write a LabVIEW program interfacing with the Agilent 34970A data acquisition unit. Have managed to get seperate VIs to acquire temperature and voltage data and to graph the data. Running them separately is fine.

However when I try run one after the other, (ie, run temperature acquisition VI, then voltage acquisition VI; or vice versa) the first one runs OK, but upon trying to run the second one I get a VISA error along the lines of "VISA write". When I try to run the first VI again, that one fails to acquire readings as well. Any way I can rectify this problem? (Want to combine the VI's into a single program.) Thanks!

[Emilie S.]

Hi Laeral:

You should be able to just open one VISA session then write and read both commands then close the session at the end. This sounds to me like an error that comes from trying to open two VISA sessions to the instrument at the same time. I have attached some very basic LabVIEW VISA code that writes and reads two different commands. Hopefully it will get you started.

Regards,

Emilie S.
Applications Engineer
National Instruments