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1/4 Bridge strain out of range on 9236, not 9219

I am trying to set up a 350 Ohm 1/4 bridge strain gauge with a 9236 on a cDAQ chassis. (We also have a 9219 for testing it). The customer verified the sensor in front of me with a non-NI stand-alone strain measurement box.

 

The device has no polarity, and we are hooking it up my connecting the device to the AI and Rch and then jumpering the Ex to the AI channel with no resistor.  While I am not sure this is the best way to do this, it is how the customer appears to be hooking it up to his stand-alone box.

 

Essentially, the measurement bottoms out.  In the MAX test panel, we saw the signal completely saturated, unmoving.  When we hooked it up to the 9219 (no jumper, just the two wires) we saw a reasonable signal.  But not with the 9236.

 

We saw this on channel 0 and channel 1.

 

1) Do we need a resistor between the AI and Ex channels?  If so, what size?

2) Is there some other possible problem?  Is it possible the module is bad?

 

 

Thanks!

 

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Ha.  I just realized that the customers' stand-alone measurement box must have a different nomenclature.  The gauge should be hooked over Ex and AI, then jumpered to the RC.

 

Love it when I tear my hair out only to figure it out after posting.

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Better than not figuring it out!  Thanks for the post though!

 

Sean

Applications Engineering Specialist - Semiconductor Test
National Instruments
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