Why is my Elvismx DMM's sampling rate is so low?

[dhm04042]

Hi, I'm using LabView 2015 Sp1, with NI PCI-6221 connecting to BNC 2120, and NI myDAQ.

I am trying to measure Voltage and Current at the same time. But PCI device can only measure up to 40mA(I'm not sure about it, since I cannot find anything about this at manual) which is quite low for my elements, since my experiment current usage is at least 0.3A.

So I have no choice but to use myDAQ's DMM port to measure current.

Anyway, I integrate both measurement device with LabView and the problem begin. When I use only PCI device, sampling rate is no problem.

But with two device, the sampling rate is down to less than 1 sample per second, which lead to inaccurate result.

I added the 'Time Delay VI Express' and set the time to 0.5 second, but it doesn't work.

Plus, I made current measurement VI independently, it shows low rate too. So I don't think it's because of orginal VI.

Are there any ways to improve sampling rate of Elvismx? Is this hardware(myDaq) limit that I can't fix this with software?

[GerdW · Accepted solution]

Hi dhm,

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@dhm04042 wrote:

I am trying to measure Voltage and Current at the same time. But PCI device can only measure up to 40mA(I'm not sure about it, since I cannot find anything about this at manual) which is quite low for my elements, since my experiment current usage is at least 0.3A.

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Your PCI-6221 can only measure voltage signals. It cannot measure current at all…

Did you read the manual?

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@dhm04042 wrote:

So I have no choice but to use myDAQ's DMM port to measure current.

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You can use current transducers to convert the current into a (standardized) voltage signal…

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@dhm04042 wrote:

Are there any ways to improve sampling rate of Elvismx? Is this hardware(myDaq) limit that I can't fix this with software?

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I could not find any specs on the sample rate of the myDAQ DMM, so I guess it only allows <10Hz sample rate.

When the hardware is so slow then there is no way to improve its speed using software…