What is sourcing and sinking in PLC?

 What is sourcing and sinking in PLC?

Sourcing and sinking are two different types of input/output (I/O) configurations used in PLC systems.

Sourcing means that the current flows from the power supply, through the output module of the PLC, and out to the field device being controlled. In this configuration, the PLC acts as a current source. In other words, the field device must be connected to the positive voltage of the power supply, while the negative voltage is connected to the PLC's output module.

Sinking means that the current flows from the field device, through the input module of the PLC, and to the power supply. In this configuration, the field device is connected to the negative voltage of the power supply, while the positive voltage is connected to the PLC's input module. In this configuration, the PLC acts as a current sink.

The choice between sourcing and sinking depends on the type of field device being used and the requirements of the application. For example, some field devices require a sourcing configuration, while others require a sinking configuration. It is important to carefully consider the requirements of the application and choose the appropriate I/O configuration to ensure reliable and safe operation.

In general, sourcing is more commonly used in applications where the field device requires a higher voltage than the PLC output voltage, while sinking is more commonly used in applications where the field device requires a lower voltage than the PLC input voltage.

differences between sourcing and sinking in PLC

Sourcing and sinking are two different methods of wiring input and output signals to a PLC, and they have some key differences:

1. Current Flow: The primary difference between sourcing and sinking is the direction of the current flow. In a sourcing configuration, current flows from the PLC output to the field device. In a sinking configuration, current flows from the field device to the PLC input.
2. Power Supply: In a sourcing configuration, the field device is connected to the positive voltage of the power supply, while the negative voltage is connected to the PLC's output module. In a sinking configuration, the field device is connected to the negative voltage of the power supply, while the positive voltage is connected to the PLC's input module.
3. Field Devices: Some field devices are designed to work with sourcing inputs or outputs, while others are designed for sinking inputs or outputs. It is important to choose the appropriate type of input or output based on the field device being used.
4. Voltage Level: In a sourcing configuration, the PLC output voltage is typically higher than the field device voltage. In a sinking configuration, the field device voltage is typically higher than the PLC input voltage.
5. Wiring: Wiring for sourcing and sinking is different. In a sourcing configuration, the field device is wired between the output module and the positive voltage. In a sinking configuration, the field device is wired between the input module and the negative voltage.

The choice between sourcing and sinking depends on the specific application requirements and the characteristics of the field devices being used. It is important to carefully consider these factors to ensure reliable and safe operation of the PLC system.