plc analog input modules and the switch

The input module will transform electrical signals into digital signals into the PLC system, contrary to the output module. I/O switch quantity input (DI), the switch output (DO) (AI), plc input output modules ,analog input, analog output (AO) module. The switch is the only opening and closing (1 and 0) of two kinds of state signal, analog quantity refers to the continuous variable.

Common I/O as follows, switch, according to the voltage level, 220VAC, 110VAC, 24VDC, by way of isolation, plc analog input module ,isolation and transistor isolation relay.