Hello:
I assume you are using the DAQ Toolbox for Matlab. If that is correct, please refer to page 5-55 and following of the Data Acquisition Toolbox from Matlab. You will see that you can use the "daqhwinfo" function to get the valid input ranges and then change the properties called "Sensor Range, InputRange, Units, and UnitsRange" to change the gain setting and scaling of units. Page 5-57 has a good example of this...
If you are not using the DAQ toolbox, please let me know how you are programming the DAQ Device and I can help you further.
Good Luck!
Sincerely,
Brooks B
National Instruments