Instantaneous chart update for Agilent 34401A DMM in LabVIEW

[adityasharma]

Hi Everyone,

I am trying to acquire 4 wire resistance measurement using Agilent 34401 DMM. I have used the multipoint reading VI file and wired a chart to the 1D measurement output data. I am getting the chart but only after the required number of samples have been taken by the DMM. The requirement is to plot the chart instantaneously and continuously, that is as soon as the DMM acquires the readings.

How can I plot the charts instantaneously? 

Thanks
-Aditya

[GerdW]

Hi Aditya,

such DMMs are rather slow compared with other DAQ equipment. (In turn they are most often more accurate.)

So your choice boils down to either

- read 4 channels at once and wait for the result: longer wait between samples, but overall faster execution

- read one channel after the other and do the channel switching on your own: smaller delays between all those samples, but overall longer measurement time due to communication overhead for channel switching…

When it comes to "instantaneously": what does the manual of your DMM say about sample rates for your kind of measurement?

[crossrulz · Accepted solution]

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@adityasharma wrote:

Hi Everyone,

I am trying to acquire 4 wire resistance measurement using Agilent 34401 DMM. I have used the multipoint reading VI file and wired a chart to the 1D measurement output data. I am getting the chart but only after the required number of samples have been taken by the DMM. The requirement is to plot the chart instantaneously and continuously, that is as soon as the DMM acquires the readings.

How can I plot the charts instantaneously? 

Thanks
-Aditya

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Don't use the Multipoint reading.  Just read a single sample.  But the read inside of a FOR loop.  So you tell how many samples you are taking by how many times you run your FOR loop.  Put your chart terminal inside of the FOR loop and wire it to the reading output.

[adityasharma]

Thanks for your suggestion.

I used a WHILE loop and got the desired result.