Access control controller
Recommended one: buy with anti crash and self-test circuit design of the access control
If the access controller crash, so that the user cannot open or closed the door can not, to customers bring great inconvenience, but also increase the project's maintenance and the maintenance cost, access controller must install reset chip or use the CPU reset function with, general 51 Series CPU is does not have the reset function, need to install 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 a three-level lightning protection design, first through the discharge tube to be generated by the lightning current and high voltage release out, the inductance and resistance circuit clamped into the circuit of current and voltage. Then through the TVS high-speed discharge residual current and voltage in the circuit 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 is against surge, and the antistatic ability will be 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.
Recommendation four: application should be simple and practical, easy to operate
If the control applications, will undoubtedly increase the engineering business to customer training cost and time, the customer is not easy to master the operation of the software will vent his anger on the project's service attitude to the payee and continued single 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.
Recommendation five: the design of communication circuit should have the function of self testing, the application of large system networking needs
Network access controller usually adopts RS485 industrial bus network, usually many manufacturers from cost savings considerations, selection of max485487 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 communication lines of communication, and unable to find exactly what controller chip damage. We recommend the use of similar max3080 of the high-grade communications chips and integrated circuits. The circuit has a self checking function, if the chip is damaged, the system will automatically disconnect his connection, making the other bus control devices on the normal communication.
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. Output is usually connected with power locks, and other high current electric inductive devices, instant off will produce feedback current impact, so the output end should be a varistor or reverse diodes and other components to be protected.
Recommendation seven: the proposed project to find the controller manufacturers or manufacturers designated agents to buy
Purchase directly only to find manufacturers or manufacturers designated agents is possible or improve the strong technical service, perfect after-sales service is guaranteed, and a reliable follow-up research and development capabilities, to ensure that the product has a continuation and advanced. Purchases from other channels may have lower prices, but technical support and after-sales service may not be enough.
Recommendation eight: 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 card reader device data terminal are not burn the circuit, through the anti surge voltage protection can be avoided because of card reading device problems affecting the quality of controller to the normal operation of the.
Recommendation nine: manufacturers need to provide the authority of the quality certification
Manufacturers need to provide the authority of the ISO9001 quality certification and quality supervision of the government's products inspection report. And pay attention to verifying the authenticity of these documents. There is a corresponding third party certification and supervision of the quality of the products will be guaranteed some. |
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