PLC WIRING

PLC WIRING

There are two types of wiring in PLC :

1. NPN WIRING (SINK)
2. PNP WIRING (SOURCE)

NPN WIRING : 

  

There is point in PLC at input side labeled as S/S that decides the Sink or Source mode. If you connected SMPS -24V to the S/S point, then all the input points of that PLC shared common -24V, this type of wiring is known as NPN wiring or Sink Mode as shown in figure below.

Now as indicated in the above diagram -24V from SMPS is connected to S/S point. So at input points you have to connect +24V of SMPS through Push buttons , Limit Switches , Sensors etc.

PNP WIRING : 

  

There is point in PLC at input side labeled as S/S that decides the Sink or Source mode. If you connected SMPS +24V to the S/S point, then all the input points of that PLC shared common +24V, this type of wiring is known as PNP wiring or Source Mode as shown in figure below.

Now as indicated in the above diagram +24V from SMPS is connected to S/S point. So at input points you have to connect -24V of SMPS through Push buttons , Limit Switches , Sensors etc.