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Follow up to an old thread - Voltage ok after SSR on VOM, but not instrument?

rbrooks

May 17, 2012
34
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May 17, 2012
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34
Please see the following older thread from here:

https://www.electronicspoint.com/threads/noob-trying-to-use-a-ssr-with-low-voltage.248043/

I had that system up and working well, but we've changed to a new acquisition system. In place of the meter, there is a national instruments NI 9205 cDAQ module.

If I meter the terminals with a voltmeter, I get 0/4.5v as expected.

The DAQ card shows a floating low voltage (from zero to 4.2v) and a high of 4.5. If I also connect the meter in parallel, I get correct readings on both.

I assume the DAQ board doesn't have enough load to allow the output of the SSR to work correctly.

Is there any way I can simulate this load? Would a resistor somewhere help? Reduce the value of the in-line resistor?

Thanks in advance.
 

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shrtrnd

Jan 15, 2010
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I don't know the system, but if you've got a floating voltage:
1) Are you reading your value at the proper ground test point on the board?
2) Is the new DAQ card iself properly gounded to your system?
 
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