PR33-14 conversion factor

I have a PR33-14, and the conversion factor that is given in the web page is not very accurate. Do I need to calibrate the gain and offset of each channel individually?

Is there a manual for the board that shows the input circuitry so I can figure this out?



input voltage = (ADC value/ max adc count)(Vref/PGA)(1/0.183)
Vref == 2.048V