Because the communication line of the access control controller is distributed, it is easy to be attacked by inductive lightning, so the access control controller must carry out lightning protection design.We suggest a three-level lightning protection design. First, release the large current and high voltage generated by lightning strike through the discharge tube, and then clamp the current and voltage entering the circuit through the inductor and resistance circuit.The residual current and voltage are then released at high speed through a TVS high-speed discharge tube before it can cause damage to the circuit.Lightning protection index requires 4000V induction lightning for 50 consecutive times without damage to equipment.The lightning protection index is high, the equipment surges, antistatic ability will be correspondingly high.Some products advertise that they also have 1500V lightning protection ability, in fact, this index is all chips themselves have, do not have the ability of lightning protection and surge.

　　Suggestion three: the storage capacity of the registration card authority should be large, the storage capacity of the offline record should be large enough, and the memory chip should be non-volatile memory chip

　　It is suggested that the registration card authority should reach 20,000, and the offline storage record should reach 100,000. 

　　This can meet the requirements of the storage capacity of the vast majority of customers and facilitate attendance statistics.Be sure to use Flash and other non-volatile memory chips, power down or impact information will not be lost.If RAM battery mode is used, information may be lost if the battery is dead or loose, or if the battery is hit by current.The access control system may fail.

　　Tip 4: The application should be simple and practical and easy to use

　　If the control program is applied, it will undoubtedly increase the training cost and time of the engineering provider to the customer. The customer is not easy to master the software operation, and will be angry at the service attitude of the engineering provider, which will bring a bad impact on the collection and renewal of orders.Customers do not understand the software is also easy to cause misoperation, resulting in practical inconvenience.Therefore, we suggest that engineering providers must pay attention to whether the operation of the software is simple, intuitive and convenient when choosing the access control controller.One-sided emphasis on powerful function is not suitable for promotion.

　　Recommendation 5: The design of communication circuit should have the function of self-detection, which is suitable for the demand of large system networking

　　The networking of access control controller usually adopts 485 industrial bus structure networking, usually many manufacturers from the consideration of cost saving, choose MAX485487 or 1487 chip, the chip load capacity is weak, usually the maximum load capacity is 32 devices, and if there is a communication chip damage in the bus will affect the communication of the whole communication line,And it is impossible to find out which controller chip is damaged.We recommend the use of high-grade communication chips and integrated circuits similar to the MAX3080.The circuit has a self-checking function, and if the chip is damaged, the system will automatically disconnect it, allowing control devices on other buses to communicate normally.

　　Suggestion 6: Relays of high power and well-known brands should be selected, and the output end has current feedback protection

　　The output of the access control controller is controlled by relays.When the controller works, the relay should be opened and closed frequently, and each time there is an instantaneous current through.If the relay capacity is too small, the instantaneous current may exceed the capacity of the relay and soon damage the relay.In general, the capacity of the relay should be more than 3 times of the peak electric lock current. It is recommended to choose the relay with rated working current of 7A.The output end is usually connected to the electrical lock and other large current inductive equipment, the instantaneous on-off will produce the impact of feedback current, so the output end should be protected by varistor or reverse diode and other components.

　　Suggestion 7: It is recommended that the engineer find the manufacturer of the controller or the agent designated by the manufacturer to buy it

　　Only by directly looking for the manufacturer or the agent appointed by the manufacturer to buy it is possible or perfect strong technical service, perfect after-sales service is guaranteed, and there is a reliable follow-up research and development ability, to ensure that the product has continuity and advanced.A controller purchased from another source may have a lower price, but technical support and after-sales service may not be enough.

　　Suggestion 8: The input circuit of the card reader needs to be protected against surge and misconnection

　　Construction contractors, often live wiring or debugging, may be due to accidental negligence, the wrong card reader line or accidentally caused by local short circuit.If there is no anti-surge and anti-misconnection protection, it is easy to burn the central processing chip, causing damage and failure of the whole controller, which needs to be sent back to the manufacturer for repair, which may delay the construction period and increase the construction cost.Good protection can make even if the power supply is connected to the data end of the card reader will not burn out the circuit, and through the anti-surge dynamic voltage protection can avoid the normal operation of the controller because of the quality problem of the card reader.

　　Suggestion 9: Manufacturers need to provide authoritative quality certification

　　The manufacturer is required to provide the ISO9001 quality certification certificate and the product inspection report issued by the government quality supervision agency.And take care to verify the authenticity of these documents.There are corresponding third-party certification and supervision of the quality of the product will be guaranteed.

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