Introduction to the Management System of Distributed Automation Access Control

At present, for remote data transmission, wireless transmission or Modem communication is usually adopted. The former is often affected by factors such as terrain and weather, and communication is often unstable or even interrupted. In contrast, the Modem remote communication method using the existing program-controlled telephone network as the communication medium is relatively stable and reliable, and the cost is low. The monitoring host communicates with the access controller via the RS-485 bus. At regular intervals, the monitoring host issues a query command. The query command contains the address of the access controller to be queried. All access controllers can receive the query command. Only the access controller with the same address as the one in the query command can respond to this command. The monitoring host processes the data uploaded by the access controller to determine whether there is an alarm. The important data and alarm information uploaded by the access control are displayed through the man-machine interface. And important data such as credit card records are stored in the corresponding form in the database. The monitoring host can also realize the remote control of the access control 1 device, realize the function of remotely opening the door, modifying the access control parameters, and the like.

The program that the software realizes and monitors the host computer is written with VC610, the database adopts SYBASE11 database system. The program uses Windows multi-threading technology to monitor the host has a data acquisition thread and data display thread. The data acquisition thread communicates with the access controller, accepts data uploaded by the access controller, and stores the data in a corresponding form in the database. The data display thread gets data from the form and displays it accordingly. Serial Port Initialization Using VC to write serial communication programs in Windows environment generally uses two methods: (1) Using serial communication functions provided by the Microsoft Win32 application programming interface (API), written in SDK. (2) Use the Microsoft VC Communication Control (MSComm). The first method is more complicated to use and highly specialized; the use of MSComm controls is easy and intuitive to program. Therefore, the second method is used when designing serial communication programs. The MSComm control provides two methods to control the serial port: the event-driven mode and the query mode. When using the event-driven mode, the On-Comm event will be triggered when a new character arrives or the port state changes. After capturing this event, you can respond to events that occur by checking the CommEvent property of the MSComm control. This method is responsive and reliable. Therefore, this design adopts this method. Modem dialing After the serial port is initialized, Modem dialing starts.

Real-time data collection After the modem dials and dials, the data collection thread starts working. The collection thread adopts a round robin mode. In each collection cycle, the monitoring host performs a data acquisition on all the devices under the serial port, and then starts the next cycle of the collection process. The system structure shows that the monitoring host displays the system structure by querying the house form, the e-quipment form, and the station form in the database in the form of a tree control (monitor host as a root directory, serial port as a subdirectory, device as a file, and tree Control expansion, you can view the entire configuration of the system, when a device is selected, it displays the real-time data corresponding to the device.Real-time data display monitoring host through the query in the database signal form for real-time data display, according to the signal characteristics of the flag, The signals are divided into different types and displayed in different lists, including the time of access control, card number and card swiping time, door switch status, and other information.