The grounding and wiring to DC 24V under normal circumstances, the ground can not meet, but the PLC panel on the ground terminal, should use special grounding wire, grounding resistance of less than 4 Q. If the expansion unit, small plc ,the ground should be with the basic unit of the grounding wire together, and access to the same ground, prohibition and other equipment are connected in series. Chart 1.


Input device using passive contact, PLC internal 24V power supply through the input device provides current to the input end of each point 7mA. 24V terminal can also provide external sensors (such as proximity switch or a photoelectric switch) to provide current, plc temperature control module ,if the sensor power supply, COM terminal is DC 24V end; if the expansion unit, it should be the basic unit and the 24V terminal connected to the expansion unit.