Signal Conditioning

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Wrong connection NI 9237


I'm using the NI9237 in order to acquire signal coming from a strain gauge. We was using the quarter bridge configuration with a NI9949 adapter (R4=strain gauge; R3=resistor) but we had a bad wiring connection.


I was looking at the following topics


According to both whe had to perform the firs connection, while we performed the second one. In fact, Rs resistor (theoretically connected to 1 and 10) is flipped (look at the attached file).


According to the simplified scheme of NI9237 the Rs is just a resistor in parallel with R3 so both circuit (the first correct one and the second wrong one) should be equivalent.


In real circuit is there any connection between pins 1 and 2 or 7 and 10? In other word, can I trust my output signal with flipped Rs connection?


Thanks you in advance

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Message 1 of 3

Hi SRaven,


If I understand your question, it is "which ShuntCal pin should be connected to which side of the shunted resistor?" It won't matter which way you connect the shunt cal lines. The shunt cal switch is bidirectional and will conduct unnoticeably well either direction.



R&D Hardware

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Good day
I am to write a code that will read data from two NI 9237 modules (6 channels in total). the modules are to read data from a force balance (strain due to force).

I know its not a matlab community but I could get help, how do I convert strain result to force using a loadcell of specification stated below and the NI 9237. being specific, I need the coefficient to convert strain value given by the daq to force.

Load Cell: STA-7 Aluminum Alloy S Type Low Range Tension/Compression Load Cell

Rated load (kg)                      1, 2, 5, 10, 25, 50
Ultimate breaking load         300% of rated load
Maximum transverse load   <50% of rated load
Output/ Sensitivity                2mV/V (±0.1%)
Zero balance              <±1% of rated load
Excitation voltage                  10vdc recommended, 15vdc maximum

ch6.BridgeMode = 'Full';
ch6.ExcitationVoltage = 10;
ch6.NominalBridgeResistance = 350;

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Message 3 of 3