AD input signal has two ways, one is single ended, the other is differential. For example , AMP(amplifer such as LM324) is the typical differential input signal device. RS485 is a kind of differential signal.
Differential has two signals to input. Single ended has one signal to input.
Single ended input signal has two types, one is bipolar , the other is Unipolar . The differential input also has the two types. Single ended bipolar signal voltage has positive voltage and negetive voltage. Single ended unipolar signal voltage is positive.
one of differential bipolar signal has positive voltage and negetive voltage. the other is the same. one of differential Unipolar signal only has positive voltage. the other is the same.