access control system: also known as access control system, which is developed on the basis of the traditional door locks. access controller is the core of the system, the use of modern computer technology and the combination of a variety of identification technology, reflecting an intelligent management tools.
so on the access controller to how to buy it?
recommended one: buy with anti crash and self-test circuit design of the access control
if the access controller crash, will enable users to open or close the door can not be closed, to bring great inconvenience to customers, but also increased the amount of maintenance and maintenance costs of the project. entrance guard controller must be installed on the reset chip or the use of the reset function of the cpu, the general 51 series of cpu is not with the reset function, the need to install the reset chip. at the same time, we must have a self-test function, if the circuit because of interference or abnormal crash, then the system can be self testing and self initiated in an instant.
recommendation two: with three anti lightning protection circuit design of access control
because the communication circuit of the access controller is distributed, it is easy to suffer from the invasion of the sensor, so the access controller must be designed for lightning protection. we propose the design of lightning protection level three, first through the discharge tube to be generated by the lightning current and voltage release, in current and voltage into the circuit through the inductance and resistance circuit. then clamped by the tvs high-speed discharge residual current and voltage in the circuit to produce damage at high speed before release. lightning protection requirements 4000v induction thunder 50 times for the equipment without damage. the lightning protection index is high, the equipment's anti surge, the antistatic ability will be the corresponding high. some products to promote their own 1500v has the ability to prevent lightning, in fact, this indicator is all the chips themselves have, do not have the ability to prevent lightning and surge.
recommendation three: registered card access to the large amount of memory to be large, offline storage of records to be large enough, the memory chip is required to use non-volatile memory chips.
it is recommended that the registration card authority needs to achieve 20 thousand, offline storage to achieve the best 100 thousand, which can be suitable for the vast majority of customers on the storage capacity of the requirements, to facilitate the attendance statistics. must use flash and other nonvolatile memory chips, power down or the impact of the information is not lost. if the use of ram+ battery mode, if the battery is no electricity or loose, or by the impact of the current information is likely to be lost, the ban system will be likely to fail.
recommendation four: the design of communication circuit should have the function of self testing, the application of large system networking needs
the network access controller is composed of 485 industrial bus network structure, usually many manufacturers from cost considerations, using max 485487 or 1487 chip, the chip load capacity is weak, usually the maximum load capacity is 32 sets of equipment, and if the bus if there is a communication chip damage will affect the entire communication lines of communication, and cannot to find what controller chip damage. we propose to use a similar max3080 high-grade communication chip and integrated circuit, the circuit has a self-test function, if the chip is damaged, the system will automatically disconnect for his connection, making the normal communication to other control devices on the bus.
recommendation five: application should be simple and practical, easy to operate
if the application control program, will undoubtedly increase the project of taking customer training cost and time, the customer is not easy to master the operation of the software will be angry at the project's service attitude of the receiving and renew will bring bad influence. customers do not understand the software is also easy to cause false operation, resulting in practical inconvenience. therefore, we suggest that the project must pay attention to the use of access controller software is simple and intuitive, convenient, one-sided emphasis on powerful is not suitable for promotion.
recommendation six: it is recommended to use a large power of well-known brands of the relay, and the output of the current feedback protection
the output of the access controller is controlled by the relay. the controller, the relay to frequent opening and closing, and each opening has an instantaneous current through. if the relay capacity is too small, the instantaneous current is likely to exceed the capacity of the relay, the relay will soon be damaged. the general situation of the relay capacity should be greater than the electricity peak current of more than 3 times, suggested the use of 7a rated current relay. the output is usually inductive devices with high current electric lock, instant on-off will produce feedback current impact, so the output should be a varistor or reverse diode components to be protected.
recommendation seven: reader input circuit need to prevent surge, anti surge protection
engineering construction, often charged for wiring or debugging, may be due to occasional negligence, the wrong card reader line or accidentally caused by local short circuit. if there is no anti surge and anti surge protection, it is easy to burn the central processing chip, resulting in failure of the entire controller damage, you need to send back to the factory maintenance, may delay the construction period, improve the construction cost. good protection can be made even if the power supply is connected in the card reader terminal data will not burn through the anti surge circuit, dynamic voltage protection can be avoided because the card is the quality problem to influence the normal operation of the controller.
recommendation eight: the proposed project to find the controller manufacturers or manufacturers designated agents to buy
only directly to find manufacturers or manufacturers designated agents to buy it is possible or perfect strong technical services, and improve after-sales service is guaranteed, and there is a reliable follow-up research and development capabilities