• What Is Sinking And Sourcing Input/Output.
  • Sinking And Souring Connection of PLC and Push Buttons.
  • Sinking And Souring Connection Of PLC And Sensor.

Sinking and Sourcing Input/output

Sinking and Sourcing terminology applies only to DC input and output circuits. 
Input and output points that are sinking or sourcing can conduct current in one direction only. This means it is possible to connect the external supply and field device to the I/O point, with current trying to flow in the wrong direction, and the circuit will not operate.

PLC systems use Input/output cards to read the signal or send the signal to the field devices. These Input/output cards are either sinking or sourcing cards.

Sinking And Souring Connection of PLC and Push Buttons.

Sinking Connection of PLC and Push Buttons
The power supply will connect to the PLC common to both the 0VDC Sinking input and output.

A sinking input card requires power to be sourced to the input to turn it “ON”. The same way a sinking output card requires power to be sourced to the load to turn it “ON”.

A sinking input or output circuit provides a path to ground for the electric load.

Sourcing Connection of PLC and Push Buttons

The power supply will connect to the PLC common to both the 24VDC Sinking input and output.

A sourcing input card required a ground connection to the input to turn it “ON”, same way a sourcing output card requires a ground connection to the load to turn it “ON”.

A sourcing input or output provides the voltage source for the electric load.

Sinking Connection of PLC and Sensor

A sinking input or output circuit requires a PNP transistor.

A PNP sensor has 24VDC output.

Sourcing Connection of PLC and Push Buttons

A sourcing input or output circuit requires a PNP transistor.

A NPN sensor has 0VDC output.