What do your table data and input signal (when using two point linear) look like? Table scales do not extrapolate beyond the table endpoints. Here's how the documentation for DAQmx Create Channel explains it:
When you use this scaling type, NI-DAQmx performs linear scaling between each pair of electrical and physical values. The input limits specified with minimum value and maximum value must fall within the smallest and largest physical values. For any data outside those endpoints, NI-DAQmx coerces that data to the endpoints.
If your table is something like:
Electrical | Physical
-----------+---------
0 mV | 0 lb
2 mV | 50 lb
and the input signal is negative, the table scale will return 0 lb.
Brad
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Brad Keryan
NI R&D
