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mesured data jump to zero

Hi all,

 

I'm using DAQ-Assistent with NI9244 and NI9247 to monitor voltage and current value of a device and perform certain command based on the mesurement. The problem is, after a while (let's say 20s), the measured value became very unstable and finally jumped to 0. I'm sure the device runs properly. Have anyone encountered  such problem before?

 

Plus: I forgot to mention that after it jumped to zero the correct value shows up again and this process continues happening.

 

Best Regards

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Hi ZeSuli,

 

which signal is unstable, the current or the voltage?

On how many channels do you measure with both modules (9244 & 9247)?

Could you provide a draft/drawing of your connection setup?

How high current and voltage do you measure?

 

Best Regards,

NI TSE

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Hi Akos_43,

 

Thank you for your reply. All the signals had this problem.I was measuring AC current and voltage value on 3 different points(and the connection does so). The currents are all less than 1A and voltage near 330V.

I later removed the all control parts and only the measure part remains. And it worked well. The devices and wires are modified so I'm not able to perform furthermore test on it. But it seems like there's something wrong with the control parts. I'm wondering if it's because of the overuse of local variable(I used a lot in the control parts) or some other kind of race condition just happened. But not sure how they influenced the measured data.

 

Best Regards,

ZeSuli

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Hi ZeSuli,

 

can you exclude a short circuit/open circuit scenario, which would cause zero voltage and/or zero current on the physical level?

Could you attach your VI?

 

Best Regards,

NI TSE

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And also a screenshot/graph/chart of the error itself...

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Hi Akos_43,

Than you for the reply. The current VI is still under development and can be a little bit confusing. All indicators on the first block of front panel will go to 0(the measured data) when this problem happens. The good thing is when I used this on another computer it worked fine but I still have no idea how this happened.

Best Regards,

ZeSuli

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Hi ZeSuli,

 

which conditions trigger this problem to happen?

Are all data set to zero right after the "Messung von Frequenzkomponenten..." Express VI, or already before it, i.e. after the DAQ-Assistant?

Which DAQmx and LabVIEW version do you use on your computer and on the other one, where your code works fine?

 

Best Regards,

NI TSE

 

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