Model 302
24-bit USB Data
Acquisition System
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INTERNAL ADJUSTMENTS


Hardware calibration is set at the factory and should never need adjustment. The software should always be able to calibrate to yield peak performance.

There are two potentiometers on the board. The potentiometer closest to the power input connector is the common-mode rejection adjustment. The other adjusts the reference voltage. Changing the reference voltage has the effect of changing the gain.

If you wish to reset the common-mode adjustment, first connect the + and - input pins of a channel to a ground on the analog input connector. Zero the channel by using the offset command. Now remove the connection to ground and connect both input pins to the 5 volt reference on pin 8 of the analog input connector. Adjust the common-mode potentiometer for a reading of zero. Repeat for best results.

The A/D gain is set by connecting a known voltage to an analog channel. Do a system calibration, then adjust the gain potentiometer to obtain the desired reading. Repeat for best results.



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