National Instruments 24-Bit Half/Full-Bridge Analog Input Module NI 9237 - Manual (Page 13)

© National Instruments Corp. 13 NI 9237 Operating Instructions and Specifications
The actual bridge excitation voltage is smaller than the voltage at
the EX+ and EX– leads. If you do not use remote sensing of the
actual bridge voltage, the resulting gain error is:
for half-bridge sensors and
for full-bridge sensors.
If you connect the remote sense signals directly to the bridge
resistors, the NI 9237 senses the actual bridge voltage and
eliminates the gain errors caused by the resistance of the EX+ and
EX– leads.
Shunt Calibration
Shunt calibration can correct for errors from the resistance of both
the excitation wiring and wiring in the individual resistors of the
bridge. Remote sensing corrects for resistances from the EX pins
on the NI 9237 to the sensor, and shunt calibration corrects for
these errors and for errors caused by wire resistance within an arm
of the bridge. Shunt calibration is most useful with quarter-bridge
R
lead
R
bridge
-----------------
2 R
lead
⋅
R
bridge
--------------------