Sensor signal
Proximity sensor: used to detect the approach of metal objects. In an automated production line, proximity sensors can be installed on both sides of the conveyor belt. When metal parts pass by, the sensor will send a signal to the PLC. For example, in an automotive parts processing workshop, proximity sensors can detect the position of metal parts such as the engine block so that the PLC can control the robot arm to perform a grabbing operation.
Photoelectric sensor: determines whether an object exists by detecting the obstruction of the light beam by the object. On a packaging line, photoelectric sensors can be used to detect whether a product passes a specified position. For example, in the process of packaging beverage bottles, photoelectric sensors can determine whether each bottle enters the packaging station correctly. After the signal is transmitted to the PLC, the PLC can control the subsequent packaging machinery to perform corresponding operations.
Limit sensor: used to limit the range of motion of the equipment. In an elevator system, the limit sensor is installed on the track of the car. When the car reaches the limit position of the floor, the limit sensor sends a signal to the PLC. After receiving the signal, the PLC controls the elevator motor to stop running to prevent the car from exceeding the safety range.
Switch signal
Manual control switch: In addition to the emergency stop switch, there are also start/stop switches. In machine tool equipment, operators control the operation and stop of machine tools through the start/stop switch. These switch signals are connected to the PLC, and the PLC controls the actions of motors, tools and other components according to program logic.
Selector switch: used to select the working mode of the equipment. For example, in industrial washing machines, there are different washing mode selection switches, such as standard washing, gentle washing, dehydration and other mode selection switches. After these switch signals are connected to the PLC, the PLC controls the motor speed, washing time, drainage and other operations of the washing machine according to the selected mode.
Analog signal
Temperature sensor signal: In industrial furnace control, temperature sensors such as thermocouples or thermal resistors convert temperature signals into electrical signals (such as voltage or current signals) and then connect to the analog input module of the PLC. The PLC controls the power of the heating equipment based on these signals to achieve precise temperature control.
Pressure sensor signal: In the water supply system, the pressure sensor converts the water pressure signal in the pipeline into an analog signal and connects it to the PLC. The PLC controls the speed of the water pump based on the pressure signal to keep the water pressure in the pipeline stable.
Flow sensor signal: In the liquid delivery pipeline of chemical production, the flow sensor can connect the liquid flow signal to the PLC. The PLC adjusts the valve opening according to the flow signal to ensure that the liquid is delivered at the set flow rate.
