Analog Inputs

An analog input is a continuous, variable signal. Typical analog
inputs may vary from 0 to 20 milli amps, 4 to 20 milli amps,
or 0 to 10 volts. In the following example, a level transmitter
monitors the level of liquid in a tank. Depending on the level
transmitter, the signal to the PLC can either increase or
decrease as the level increases or decreases.