Hello PLC professionals! As technicians, we know that sensors are an essential component of any industrial automation system. They are responsible for transmitting data and signals to the PLC, which then makes decisions and controls the machinery accordingly. In this article, we will be discussing the circuit connection method of the NPN sensor type, which is widely used in the industry. Let's dive in!
The NPN sensor, also known as a sinking sensor, is a type of proximity sensor that operates on a negative logic. This means that the output of the sensor will be connected to the negative side of the power supply. In simpler terms, when the sensor detects an object, it will provide a ground signal to the PLC. Now, let's take a closer look at the circuit connection method of this type of sensor.
The NPN sensor has three wires - brown, blue, and black. The brown wire is the positive supply, the blue wire is the negative supply, and the black wire is the output. When connecting the sensor to the PLC, the brown wire is connected to the positive terminal of the power supply, the blue wire is connected to the negative terminal of the power supply, and the black wire is connected to the input terminal of the PLC.
It is important to note that the brown and blue wires must be connected to the correct power supply terminals. If they are reversed, the sensor will not function properly, and in some cases, it may even get damaged. This is because the sensor operates on a negative logic, and reversing the power supply would result in the sensor receiving a positive signal, which it is not designed to handle.
Moreover, the black output wire of the NPN sensor is usually connected to the input of the PLC using a sinking configuration. This means that the PLC uses its internal pull-up resistor to provide a 24V signal to the input. When the sensor detects an object, it will ground the input, and the PLC will register it as a logic 0. To ensure that the sensor is functioning correctly, it is recommended to test the output voltage using a multimeter.
Now, let's take a look at a practical example of connecting an NPN sensor to a PLC. For this example, we will be using a proximity sensor to detect the presence of a box on a conveyor belt. The brown wire of the sensor is connected to the positive terminal of the power supply, the blue wire is connected to the negative terminal of the power supply, and the black wire is connected to the input terminal of the PLC. The input terminal of the PLC is then connected to a digital input channel.
In this setup, when the sensor detects a box on the conveyor belt, it will provide a ground signal to the input of the PLC. The PLC will then register it as a logic 0 and execute the programmed instructions accordingly. This is a simple yet effective way of using the NPN sensor to control the machinery in an industrial setting.
In conclusion, the NPN sensor is a crucial component of industrial automation systems, and understanding its circuit connection method is essential for any PLC professional technician. By following the correct wiring methods and testing the output voltage, we can ensure that the sensor is functioning correctly and providing accurate data to the PLC. I hope this article has provided you with a better understanding of the NPN sensor and its circuit connection method. Happy coding, fellow technicians!