Multifunction DAQ

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Connecting 5 common supplied fullbridges to a NI9237

I want to measure a 5 balance bridges with two NI9237 modules.

The balance is wired with a +exc and a exc- line, also a sense+ and a sense- line.

All bridges are output with a AI+ and AI- line.

I can not change this way off wiring, because it is a closed balance with fixed wiring.

I have the first bridge connected and works fine, with all lines connected (AI+, AI-, Sense+, Sense-, EXC+ ,EXC- (external supplied with 5.0 Volt by the NI9237).

Both NI9237's have the same external excitation source 5.0VDC.



Now I only have 4 twisted lines (with AI+ and AI-) from the other bridges, how can I connect the next 4 channels?

Can I jumper the Exc+ and Exc- and also the Sense+ and Sense- lines to the other channels and connect the seperate AI+ and AI- lines from the other bridges
to the other channels?

Assuming that the channels have no active Sense (to adjust the Exc lines) and that the sense lines are only used to divide the actual voltages by the sense voltage measured, that must be an option?


I am not interested in a STRAIN output, I want to measure mV/V


Regards Hans Willemsen

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Message 1 of 5

Please share a simple electrical diagram of your "5 balance bridges" to ensure I am on the same page.



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Message 2 of 5

balans 5 bridges .jpg

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Message 3 of 5

see my drawing!

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I need to measure the 5 bridges on a cRIO with more NI9237-modules (only 4 channels per module).


1. Is the module compensating the measured sense voltage on the excitation leads or
    does it only use the sense lines to divide the bridge output by sense line voltage to 

    get a ratiometric output (mV/V)?

    I suspect that the second statement is the truth, because the module can not 

   correct an externally fed excitation voltage! 


2. Connecting a 5 bridge balance on two modules (external excitation)

    Then the wiring according the drawing must be correct!Connections 5 bridges balance on SGM.jpg 

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