8.1 Unipolar and Bipolar Inputs

Diamond-MM-32DX-AT can measure both unipolar (positive only) and bipolar (positive and negative) analog voltages. The full-scale input voltage range depends on the Gain, Range, and Polarity bit settings in the Analog Configuration Register at Base + 11. In front of the A/D converter is a programmable gain amplifier that multiplies the input signal before it reaches the A/D. This gain circuit has the effect of scaling the input voltage range to match the A/D converter for better resolution. In general you should select the highest gain you can that will allow the A/D converter to read the full range of voltages over which your input signals will vary. If you pick too high a gain, then the A/D converter will clip at either the high end or low end, and you will not be able to read the full range of voltages on your input signals.