Single-Ended and Differential Inputs
One of the most common questions asked is the difference between single-ended and differential inputs.
Single-ended inputs: A single-ended input has no common mode range because there is only one low wire, which is shared by all inputs. For example, if you have a board with 16 single-ended inputs, there will be 16 high lines and one low line.
Differential inputs: A signal input circuit where signal low and signal high is electrically floating with respect to analog ground. For example, a differential input card will have one high and one low pin for each input. This allows the measurement of the voltage difference between two signals tied to the same ground and provides superior common mode noise rejection. Whenever electromagnetic interference or radio frequency interference is present, a voltage can be induced on both signal wires. The effect on a single-ended input is usually a voltage fluctuation between signal high and signal ground.