Question: what is digital and analog signal in plc?
Answer: Common PLC input/output (I/O) can be analog and/or digital. ... Common examples of standard analog I/O are 4 to 20 mA for current with voltages ranging from 0 to 120 Vac or 0 to 48 Vdc. By contrast, a digital (or discrete) signal is one with a value at a specified interval of time.