Programmable Logic Controller (PLC) is an electronic control device based on computer technology and designed in a professional industrial environment. This device mainly uses programming method to achieve Mechatronics design.
Therefore, in the modern industrial field, the programmable controller has the characteristics of wide application range, powerful application function and wide field. The programmable controller has become an indispensable application technology in the process of modern industry. This paper mainly studies the application of programmable controller in elevator system.
Elevator electrical part mainly includes six parts, which are traction motor, automatic door machine, floor indicator, call floor, control box and stop device. There are many types of programmable controller PLC, which can be divided into different types according to different functions and instructions, but each kind of PLC has similar characteristics in working principle and structure.
The general PLC device is mainly composed of CPU, storage device and input and output device. In this paper, OMROM C60P professional programming software SSS and LSS module are used to design the elevator control program. The software module of PLC programmable controller for elevator is designed in engineering. The design idea of this part is to divide the functional modules of the system effectively, and design the effective trapezoidal diagram according to the dividing modules. In the elevator control system based on PLC, it can be divided into hall door switch control module, layer selection control module and elevator operation control module. All the functions of these modules are centralized in PLC for control.
The advantage of centralizing all control functions in PLC is that the structure is clear and easy to debug, and the corresponding control functions can be added according to the flexibility requirements.
In the process of design, attention should be paid to the coordination of each functional module. In the process of closing the door, the signal is detected by infrared ray. When the elevator runs in flight, the car’s floor has a call outside the hall or an order to open the door inside the car. The elevator opens the door automatically. The elevator’s floor opening can also be realized by the bottom key, the floor automatic and the infrared sensor when the door closes. If the car is parked on the third floor, then 1002 is ON, 0102 is ON when there is a call signal outside the hall on the first floor, and when there is no fixed downward direction, 1309 is ON when parking, which sends out the control signal of opening the door on this floor. When the door is in place, thermostatic element if there is no open limit switch or the limit switch fails, the door motor will be blocked due to the suction of the open relay, and the motor may burn out in a long time.
For this reason, a door motor protection program is designed.
When the opening time exceeds 2-3 seconds of the normal opening time, the opening signal is automatically disconnected and the door is stopped by timer. If there is no external open signal, i.e.
0002 and 1309 are ON, the timer TIMOO starts timing, and when the time comes, if the limit switch is still not activated, 0604 is disconnected through TIM00 closing point and the door stops opening. The timer is self-locked by TIM00 open point. 0604 maintains that when OFF has an open signal, 0002 or 1309 is ON. The closed-point OFF, the timer reset and the closed-point ON can be controlled again. Floor counting involves floor counting, car speed change, floor treatment, parking and other issues. The solution of these problems is based on the pulse of rotary encoder. The selection of the number of pulses per revolution of rotary encoder depends on the frequency, step speed and counting accuracy of the allowable input of PLC.
From the formula, each pulse is equal to 0.6 mm of car operation. Relative counting method is adopted, counting from the level point to the next level point at a time, and then resetting the high-speed counter.
Each layer follows. Start counting; storey count is stored in another counter. If the high-speed counter count accumulates to the set value, the high-speed counter resets. At the same time, adding or subtracting one floor counter according to the direction of operation indicates that the distance of one floor has been run. The characteristic of this counting method is that the pulse number of speed change point, door area and flat point of each floor is the same, which is suitable for elevator control with the same floor height.
Synthesizing 1 and 2, considering the bottom hole height and the floor height, set the DM value between 2990 and 5004. The input pulse of high-speed pulse through PLC is accumulated and stored in CNT47 by the instruction of high-speed counter FUN (98). The instruction can compare the current count value with the upper and lower limits set in DM32-DM37 of data register.
Then, according to the comparison result, the corresponding output is generated in the channel specified by the instruction of FUN (98).
If the current count value is within the set upper and lower limits, the corresponding output point is 0N, and vice versa, OFF. By setting the upper and lower limits, the speed change signal and the level signal can be sent out in turn according to the distance principle. The programmable logic controller (PLC) is embedded in the elevator as a core component, which is combined with the control components and other peripheral components to form the elevator control system. Compared with the elevator control system composed of traditional relays, the elevator control system assembled by PLC has higher reliability and maintainability. The utility model has the characteristics of longer service life and higher control level.