PLC Based Automatic Door Opening System

 Hello,and welcome back to enghme.In order to improve the reliability of automatic door operation, S7-200 programmable logic controller (PLC) is used as the core of the automatic door system. The principle of the control system is analyzed, the hardware of the control system is described, and the working process of the control circuits such as human detection sensors, automatic door position detection, and obstacle detection is introduced. This paper introduces how to choose PLC type to really solve the I/O command. Combined with the operation characteristics of programmable controller, the work flow of the system is rationally optimized. On this basis, using the structured programming method, the program flow charts of the main program module, the door-opening subprogram module and the door-closing subprogram module are developed. The control system was debugged and adopted. The practical application shows that the control system is good and reliable.

Working Principle

The system uses PLC as the main controller of the automatic door. When the induction detector to detect someone close, the pulse signal is transmitted to PLC, PLC judges after the notice of the motor running, while monitoring the motor rpm to inform the motor at a certain point in time acceleration and running into the slow, motor running forward drive door open. When the door is opened, it is judged by PLC and remains open until there is no one on the door. If there is no one on the door, PLC notify the motor as a reverse movement, in a short time to automatically close the door. In the closing process, if someone close to the probe, PLC automatically switch to the state of the door. 

problem plan

  • We will use a PLC S7-300 for this application. We will also use the TIA Portal software for programming.

  •  In this system, when someone enters the infrared sensing area, the door opening motor starts to work and automatically opens the door until the door touches the door opening limit switch.

  • If the door touches the door open limit switch for 8 seconds and no one enters the sensing area/area, the door close motor starts to close the door automatically until the door touches the door close limit switch.

  • During the door closing process, if someone enters the induction field, please stop closing the door immediately.

 List of inputs and outputs:

List of inputs

    Infrared sensor :I0.0
    Closing limit switch :I0.1
    Opening limit switch :I0.2

List of outputs

    Opening motor :Q0.0
    Closing motor :Q0.1

PLC ladder diagram of automatic door control system:

When infrared sensor is detected (I0.0), door opening motor (Q0.0) will start. The door will be open. When it touches the close limit switch (I0.1), opening motor will be stop.

When the door touches the opening limit switch (I0.2), timer will be executed.

After 10sec time closing motor (Q0.1) will start. When it touches the closing limit switch, closing motor (Q0.1) will turn OFF.

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