Solution
There are different causes of measurement drift in a strain gauge measurement, some of these could be external, like environmental temperature changes; related to the sensor, like self-heating or using an incorrect excitation value; and related to the measurement device.
The NI module is the measurement device, so here are some potential causes related to it. Initial drift could be due to the device warming up in the chassis as well as the excitation source stabilizing in terms of temperature. This is expected if the Strain Input module didn't get any warm up prior to the acquisition as suggested in the specifications of the module.
To use the module within its expected performance, we recommend the following:
- Let the device warm up from initial boot as well as enable the excitation voltage. This will allow the module to stabilize all it's components. The specifications suggest 15 minutes warm-up, but it may take 15-30 minutes depending on the environmental conditions.
- After the warm-up time, enable Offset Null and Shunt Calibration as part of your acquisition, then let the device start measuring under no-load conditions.
- Consider turning the chassis fan mode to HIGH instead of AUTO, as this may help things to stabilize faster.