Digital Multimeters (DMMs) and Precision DC Sources

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PXIe 4081DMM does not work with software trigger and multiple fetch

 

Hello! I want to make a measurement to see if software trigger is working and I want to acquire multiple sample for 1 software trigger. When I am using only one sample for number to fetch everything is working fine. 

The problem is when I want to acquire multiple samples, at least 2, my program is not working anymore and it freeze on fetch vi. Can you help me with this problem? Thanks in advanced!

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You need to configure the DMM to perform two measurements, as by default it performs one.

The reason Fetch.vi freezes is because you are telling it to fetch 2 measurements and to never time out (by passing -1), but the DMM will never perform the second measurement as configured.

 

Please look at the examples included by launching the LabVIEW Example Finder.

 

Marcos Kirsch
Chief Software Engineer
NI Driver Software
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Hello Kirsch, 

Thank your for your response, but I do not get it, except timeout(-1). Fetch.vi can perform multiple measurements?

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niDMM Fetch.vi does not perform any measurements. What it does is allow you to grab the measurements that were previously acquired by the DMM and are sitting in a FIFO waiting for you to retrieve them.

 

In the screenshot of your program you posted:

 

  1. niDMM Initiate.vi tells the instrument to wait for a software trigger
  2. niDMM Send Software Trigger.vi sends the trigger, which tells the DMM to perform the Measurement
  3. niDMM Fetch.vi attempts to retrieve 2 measurements. But because the instrument only performed 1 and because you used infinite timeout, it blocks forever.
Marcos Kirsch
Chief Software Engineer
NI Driver Software
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Hi, 

 

 Your DMM does not measure 2 samples , but only 1 sample. So firstly you have to set the Trigger Count and Sample Count parameters of niDMM Configure Multi Point VI  that you already have in your block diagram. Check out these links, and hope you'll get it right)) 

niDMM Fetch Multi Point - NI Digital Multimeters Help (NI-DMM 18.1) - National Instruments

niDMM Configure Multi Point - NI Digital Multimeters Help (NI-DMM 18.1) - National Instruments

 

 

Good luck))

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