hotel door lock system 3
- Apr 13, 2018 -
The key technology
In order to improve the safety and reliability of intelligent combination lock, this paper except on the device select measures (e.g., with low power consumption, wide temperature range of devices), also adopts some key technologies in the design.
2.1, line multiplexing technology
Intelligent monitor and electronic locks different place, intelligent monitor electronic locks the required power supply and receive its send alarm information and status information.If the communication circuit and power supply circuit separate way, some will inevitably increase the cable, the increase of potential safety concerns.This article adopted line multiplexing technology, only with a 2 core cable, implements the power supply and information transmission.Schematic diagram is shown in figure 3.
In the sending end, electronic locks by pulse transformer T will be sent after a good data signal booster;At the receiving end, T will the received data signal pulse transformer step-down after send demodulator, to reduce the carrier signal loss in the transmission process.In order to reduce the mutual interference between communication and power supply, choice of choke, coupling capacitance C L to comprehensive consideration.
Set fo = 400 KHZ carrier frequency, in order to ensure that the vast majority of signal energy transmitted to the receiving end, take the L = 33.7 mu H C1 = 0.047 u F.
2.2, current monitoring technology
In order to prevent communication lines of man-made destruction and electromagnetic actuators for some reason cause excessive current flows through the electromagnetic coil and burning coil, this paper adopts the current monitoring technology in the intelligent combination lock design.Current monitor by MAXIM company's current/voltage conversion chip MAX471.The chip will be measured current I translate into the output voltage U, and a large measuring range, high precision, is directly proportional to the measured current output voltage U and I wait for a characteristic.Current monitor output voltage to send A/D converter, single-chip microcomputer by reading A/D conversion results, obtained the change of the current situation in line, through the analysis of abnormal in time, send out alarm signal.Principle of the circuit as shown in figure 4.
2.3, data communication and the pretreatment technology
Intelligent monitor receives the locks from the state information (including the lock open, close, the password for the first time, the second password is wrong, wrong password, etc.) for the third time, through the electromagnetic actuator coil current value, and read The Times communications lines of power supply current value, combination form a block of data, the operating status of 1 byte, power supply current of 2 bytes, coil current of 2 bytes.Intelligent monitor in the process of communicate with electronic locks, always in a state of receiving.In order to improve the communication reliability, this paper adopt the way of repeating in the communication protocol, electronic locks send 5 times for each set of data repeat, intelligent monitor after received this set of data, USES the law of decoding error correction of large number, ensures the accuracy of the data reception.In addition to save memory to received data by adopting the technology of pretreatment, namely each receives a data, will first compare the data and setting of threshold method, if is greater than the threshold, emit transfinite alarm;If less than the threshold, the data with the received similar data comparison, with strong reserves.Such storage of data for the maximum of every day, the flow chart as shown.
2.4 and intelligent analysis
Intelligent analysis and prediction technology is based on each time the received data blocks, compare to previous similar data record values, analyze the operation of the change of the current size and trends, found problems in time, and report on management, so as to enhance the reliability of the whole system.