An electrical device called a programmable logic controller (PLC) is used for managing and automating processes in industries. It consists of a central processing unit, input and output modules, and a programming device. PLCs are widely used in various industries such as manufacturing, oil and gas, and food processing, to name a few.
One of the key features of a PLC is its ability to control external devices through input and output modules. Sinking and Sourcing in this regard refer to the communication between PLCs and external devices.
Sinking and sourcing are two different methods of connecting external devices to a PLC's input and output modules. These methods are used to ensure proper communication between the PLC and the connected devices.
The concept of sinking and sourcing can be better understood with the help of a simple example of a light bulb connected to a PLC.
Sinking
In the sinking method, the positive terminal of the light bulb is connected to the PLC's output module, while the negative terminal is connected to the power supply.
This means that when the output module of the PLC is activated, it provides a path to ground for the current to flow through the light bulb, thereby turning it on. In this method, the PLC 'sinks' the current from the external device.
Sourcing
On the other hand, in the sourcing method, the positive terminal of the light bulb is connected to the power supply, and the negative terminal is connected to the PLC's output module.
Here, when the output module is activated, it provides a path for the current to flow from the power supply through the light bulb, turning it on. This means that the PLC 'sources' the current for the external device.
Why do we need these two different methods?
The answer lies in the different types of devices that can be connected to the PLC. Some devices, such as sensors, are designed to provide a current, while others, such as motors, require a current to be provided to them. This is where the concepts of sinking and sourcing come into play.
Sinking and sourcing also play a vital role in PLCs' safety and reliability. In industries where high voltages are used, it is important to ensure that the PLC's internal circuitry and programming are not affected by electrical noise.
- Using the sinking method, the PLC acts as a load and provides a short-circuit to ground for any induced electrical noise, protecting its internal circuitry.
- In contrast, using the sourcing method, the PLC can act as a signal source, providing a more robust and reliable connection to the external device.
- Moreover, machines and equipment in industries often require a large number of sensors and devices to be connected to the PLC. In such cases, using the sinking method is more efficient as it allows for grouping the devices in parallel and connecting them to a single output module. This reduces the number of output modules required, saving space, cost, and simplifying the wiring process.
Both sinking and sourcing methods have their advantages and limitations, and the choice between the two ultimately depends on the specific requirements of the industrial process. Some PLCs also have the capability to switch between sinking and sourcing methods, providing flexibility in handling different devices.
In conclusion, sinking and sourcing are two essential methods used in PLCs to connect and control external devices. These methods have an impact on the efficiency, safety, and reliability of the overall industrial process.
As technology advances, PLCs continue to evolve and offer more options to optimize the use of sinking and sourcing methods, making them an integral part of modern industrial automation systems.
For More Understanding:See this video about sinking and sourcing
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