Application Design of Haiwei PLC, H01zb Module and Pc2zb Module in Parking Lot Control System

With the rapid development of China's economy and the continuous improvement of living standards, the ownership of family vehicles and social vehicles is increasing. The construction of parking lot has become an indispensable part of most construction projects. Only when a parking lot is equipped with a good control system can it save manpower, improve the utilization of parking space and alleviate the contradiction between supply and demand of social parking spaces. The system uses h01zb module and pc2zb module of Haiwei company to establish a wireless ZigBee network and touch screen for communication. H01zb wireless module adds a disconnection response retransmission mechanism on the application layer based on the retransmission mechanism of ZigBee protocol, which greatly improves the stability of communication. No adverse conditions such as communication interruption are found during use, It provides convenience for car owners to stop quickly.

Control diagram

1. Use LED monochrome display screen to display the remaining number of vehicles at the garage door; When there is still parking space, the entrance gate can open the door to allow vehicles to enter and park;

2. Automatically collect the status of vehicles entering the garage, obtain the card number by swiping the card, enter the parking lot, and guide users to quickly find parking spaces to reduce users' parking time;

3. In order to prevent disorderly parking in the user's parking area, an ultrasonic parking space sensor is set above the parking space to detect whether the vehicles are placed disorderly;

4. When the user's vehicle leaves the site, the card swiping form is adopted. The parking time is automatically calculated according to the admission time and exit time, and the receivable fees are automatically calculated according to the parking time and charging standard. The user can leave only after paying the fees.

2.1 composition of hardware system

In the control system of this paper, the signal collected by the system is logic switch signal, and the number of input points increases with the increase of the number of cars in the parking lot. This requires that PLC has strong point expansion capability, while Haiwei PLC can expand 7 modules. Most of the expansion modules also support remote function and can read the information of corresponding points through Modbus protocol. Small computers have the expansion capability of medium-sized computers, and there is no problem in dealing with general parking lot control systems. In addition, the PLC shall communicate with the LED monochrome display screen to send the remaining parking space information. At the same time, the PLC shall also collect the card number information. In order to realize the monitoring of the card number, the card number information, as the key information, will be transmitted and communicated through the system at any time. Therefore, the information communication in the system is frequent, which requires the PLC to have strong communication ability. In terms of communication, it is precisely the advantage of Haiwei PLC. It is simple and easy to use. One communication command can complete complex communication functions, which can greatly reduce the debugging time of the system and improve efficiency; Considering the above system requirements, Haiwei PLC is selected as the controller of the control system.

2.2 selection and use of controller and module

The selection of PLC host is generally on the premise that the function meets the requirements. Considering that more register elements may be used, the system selects H-series host. The H series host is equipped with RS232 and RS485 communication ports. The functions of each communication port are the same. It can be programmed and networked, and can be used as a master station or a slave station. In this system, the RS232 communication port on the host is used for information exchange between the card reader and PLC, and the LED monochrome display screen uses RS485 on the host for communication.

In order to save time for users, the system specially places a touch screen at the card collection place, and uses h01zb module and pc2zb module to realize wireless communication between PLC and touch screen. H01zb module is directly hung behind the host; The pc2zb module is connected to the touch screen. The following figure is the networking diagram:

Networking diagram

After normal communication, the user will have a clear understanding of the layout of the parking lot and the distribution of spare parking spaces through the touch screen. The screen of the touch screen will be displayed back and forth in the overall layout of the parking lot and the screen with the most parking spaces, guiding the user to quickly reach the parking area. The following figure shows the touch screen display of one area:

Touch screen area display

1. Powerful communication and simulation functions

Haiwei PLC has many powerful innovative and convenient instructions. No matter what communication protocol, it only needs one communication instruction to complete complex communication functions. It is the first PLC programming software with built-in simulator in China, which fully realizes the simulation operation of PLC. Both ordinary programs and communication simulation programs can be simulated. Greatly reduce the on-site commissioning time, reduce the commissioning difficulty and improve the commissioning efficiency.

2. Wireless networking is simple and convenient, and communication is stable

It is simple and convenient to use h01zb module and pc2zb module of Haiwei company to set up a network. There is no need for users to configure ZigBee parameters, just dial the dip dial switch provided by the lower module. The communication has high stability. Based on the retransmission mechanism of ZigBee protocol itself, a disconnection retransmission mechanism on the application layer is added.

3. Instead of manpower, it can improve efficiency and save cost

The parking lot control system not only improves the work efficiency of modern human beings, but also greatly saves human and material resources and reduces the operation cost of the company; The parking order is standardized, the phenomenon of arbitrary charging is avoided, and the whole management system is more safe and reliable.

4. Visual interface allows users to reduce parking time

When queuing to pick up the card, the user can see the regional layout of the whole parking lot on the touch screen and the simplest route to the area with the most parking spaces, which reduces the user's parking time. Although it is only a little time, the user's experience is different from now on, and the humanized design can always attract more users.