Access Control System Application and Analysis of Door Magnetic Principle

The door magnetic system in our life can be generally divided into three parts: the door magnetic switch, the door magnetic sensor (detector) and the door magnetic alarm. Some access control systems are based on intelligent bus and the same system platform, so smart terminal smart home can easily access the video doorbell system door machine and management center to realize visitor intercom, message, photo and access control functions, and become our family safety. The first line of defense.

Principle analysis of door magnetism

First, the working principle of wired magnetic sensor

In the smart home access control system, the function of the magnetic switch is responsible for the magnetic power of the door, the magnetic circuit (closed door), the degaussing (opening), the magnetic installation on the door and the door cover, the switch is installed in the house, with automatic Used by the door closer, it can generally withstand a pulling force of 150 kg.

The wired door magnet is more concealed for the embedded installation, and the opening and closing of the induction door and window is suitable for the wired normally closed/normally open switch signal of the wooden or aluminum alloy door and window. Door magnets are used to detect whether doors, windows, drawers, etc. are illegally opened or moved. It consists of a wireless transmitter and a magnetic block. The door magnetic system is actually the same as the bed magnet. Here, the door magnet is used as an example to draw the rope displacement sensor.

Second, the working principle of wireless magnetic sensor

The wireless door magnet is composed of a wireless transmitting module and a magnetic block. The wireless transmitting module has a "steel reed" component at two arrows, when the distance between the magnet and the reed pipe is kept within 1.5 cm. The steel spring tube is in the off state. Once the distance between the magnet and the steel spring tube exceeds 1.5 cm, the steel spring tube will close, causing a short circuit, and the alarm indicator light is on, and an alarm signal is sent to the host. The wireless door sensor is used to monitor the switch status of the door. When the door is opened for whatever reason, the wireless door sensor immediately transmits a specific radio wave and alerts the host remotely.

The wireless door alarm wireless alarm signal can transmit 200 meters in the open space and 20 meters in the general house, which is closely related to the surrounding environment. The wireless door magnet generally adopts a power-saving design. When the door is closed, it does not transmit a radio signal. At this time, the power consumption is only a few micro-amps. When the door is opened, the wireless alarm signal is immediately transmitted for about 1 second, and then stops by itself. At this time, even if the door is always open, it will not be fired again. This is to prevent the internal battery from running out due to continuous transmitter emission, which affects the alarm. The wireless door magnet is also designed with a battery low voltage detection circuit. When the battery voltage is lower than 8 At the time of volts, the LP LED below will illuminate. In this case, the A23 alarm battery must be replaced immediately, otherwise the reliability of the alarm will be affected.

The wireless door sensor is generally mounted on the inside of the door. It consists of two parts: the smaller part is a permanent magnet, the inside has a permanent magnet to generate a constant magnetic field, and the larger is the wireless door magnet body. There is a normally open reed switch. When the permanent magnet and the reed switch are close together (less than 5 mm), the wireless magnetic sensor is in the working state. When the permanent magnet leaves the reed pipe for a certain distance, the wireless door The magnetic sensor immediately transmits a high-frequency radio signal of 315 MHz including the address code and its own identification code (that is, the data code). The receiving board determines whether it is the same alarm system by identifying the address code of the radio signal, and then identifies it according to its own identity. The code (that is, the data code) determines which wireless door magnetic alarm load cell is used.

Access control system door magnetic application

The closing signal is output when the door is closed (the resistance is 0 measured by the multimeter, and the open signal is input when the door is opened. (Measure the resistance infinity with a multimeter). The magnetic field of 90 on the market is such a characteristic, and there are a small number of magnetic characteristics of the door opposite, or closed. Both the signal and the open signal have outputs (three lines, one is common, and the other two are combined with the common line to output open and close signals respectively. When used, one of them can be selected, and one of the features is idle.) Some electric locks The same is true for the door magnet, for example: 5-wire electric plug lock (2 is the power supply, 3 is the door magnetic signal line), 8-wire electric plug lock (not only with the door magnetic output, but also with the lock position status output), do not use The line is idle.

When the software is monitored in real time, you can see whether the status of each door is open or closed. It is possible to cooperate with the access controller to enable the door to be illegally inserted (no legal operation of swiping or pressing a button, and the door is opened, for example, open or open). The door can be activated with the access controller for a long time without turning off the alarm.

If you do not need these features of the access control system, you can not connect the magnetic door. If these functions are required, the door magnet is connected to the magnetic input point of the controller without distinguishing between positive and negative. If a large multi-door access control system uses only a few doors to use the functions of the door magnet, the other magnetic input points are shorted by wires to avoid false alarm signals.

The smart home system of the Internet of Things consists of a home environment-aware interaction layer, a network transport layer, and an application service layer. The home environment-aware interaction layer is composed of various sensor nodes with wired or wireless functions, mainly to collect household environment information, acquire owner status, and enter guest identity features. The network transport layer is mainly responsible for home information and director control information. Transmission; the application service layer is responsible for controlling the home facility or application service interface.

The door magnetic sensor in the door magnetic system belongs to the family environment sensing interaction layer. The English name of the wireless door magnet is Doorsensor. There are two ways for a gangster to enter the house from the door: one is to steal the key of the owner and open the door; the other is to open the door with the aid of a tool. Regardless of the way the gangster enters, he must push the house door open. Once the thief pushes the door open, the door and the door frame will be displaced, and the door magnet and the magnet will also be displaced at the same time. The electric wave signal is immediately transmitted to the host, and the host sounds an alarm and dials 6 preset telephone numbers. Thereby providing a more intelligent security protection for home life. Protect family life and property security.