Hello all,
I have a real problem in understandig, how the accuracy of the quarter-bridge-measurement with the NI 9219 ist calculated.
I'm using a 350 ohm strain gauge für strain measurement.
The absolute accuracy is usually given by:
Absolute Accuracy = (Gain Error * Reading) + (Offset Error * Range) + Noise+ Drift
The problem is, that in the NI 9219 Datasheet no range is given. The selected range in the NI MAX is only used to improve the resolution of the ADC, or am I wrong? Further more, the quater bridge is sourced by a not specified current. In this thread is explained, that the NI 9219 uses a constant voltage excitation of 150 mV (Datasheet page 13) to source this current.
Can someone explain me, how I calculate with these informations the accuracy of my strain measurement?
Best ragards,
Ivo