Signal Conditioning

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NI 9205: Seeing signal in two channels

Hello,

 

I am trying to messure two singals. They have diferent references.

 

Signal 1: Sine 40hz, current signal converted to voltage with a 1M resistor, - is connected to the case of the machine that produce it

 

Signal 2: Sine20hz, generated by a signal generator

 

When I have the two signals on, the second signal ist disturbed by the first. The resultant waveform seems to be the addition of the two.

 

When I turn off one of the signals, I can see the activated signal in both of the channels.

 

Things I have tried:

1. Connect the two - terminals together, connect them to the COM port and RSE measurement: Problem is present.

2. Connect the two - terminals together, then connect that tru a 1M resistor to the COM. Aditionally connect the - Terminals to the corresponding diferential port and diferential measurement: Problem is present.

3. Connect the two - terminals together tru a 1M resistor, then connect that  to the COM. Aditionally connect the - Terminals to the corresponding diferential port and diferential measurement: Problem is present.

 

Can some one nudge me in the right direction, how can I connect the signals?

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Projektingenieur
Restbust, Simulations and HiL development
Custom Device Developer
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I tried also following this guide, but my device do not allow the use of duplicated channels

 

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000YHy6CAG&l=de-DE

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Projektingenieur
Restbust, Simulations and HiL development
Custom Device Developer
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Message 2 of 2
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