Solution
This is expected behavior. The NI 9237 returns its readings in volts per volt of excitation rather than in volts. If you need to know the voltage value of your measurement, you need to multiply your reading by the excitation voltage.
For example, if you attempt to measure 0.01 V using the test panels, the NI 9237 will read 0.004 V because it defaults to an excitation of 2.5 V. Based on this the actual voltage at the input to the module will be as follows:
2.5 V * .004 V/V = .01 V
Note: Some sensor manufacturers provide the scaling information of their sensors in V or mV. Make sure you are using a scale or table in mV/V when you configure it in MAX or in LabVIEW. Otherwise, the measurements will be incorrect because you can only select mV/V or V/V to scale the data.