Suggestion 1: purchase access control with anti crash and self check circuit design controller
If the access controller crashes, the user will not be able to open or close the door, which will bring great inconvenience to the customer and increase the maintenance amount and cost of the engineering company. The access control controller must be equipped with a reset chip or a CPU with reset function. Generally, 51 series CPUs do not have reset function and need to be equipped with a reset chip. At the same time, it must have the self check function. If the circuit crashes due to interference or abnormal conditions, the system can self check and self start in an instant.
Recommendation 2: Access controller with three-level lightning protection circuit design
Since the communication lines of the access controller are distributed and vulnerable to the attack of inductive lightning, the access controller must be designed for lightning protection. We suggest to adopt a three-level lightning protection design, first release the large current and high voltage generated by lightning stroke through discharge tube, and then clamp the current and voltage entering the circuit through inductance and resistance circuit. Then, the residual current and voltage are released at high speed through TVS high-speed discharge tube before they damage the circuit. The lightning protection index requires that the 4000V induction lightning has no damage to the equipment for 50 consecutive times. The lightning protection index is high, and the anti surge and anti-static capacity of the equipment will be correspondingly high. Some products claim that they also have the lightning protection capability of 1500V. In fact, all chips have this indicator, and do not have the lightning protection and surge protection capability at all.
Recommendation 3: The registration card should have a large capacity of authority storage, and the storage capacity of offline records should also be large enough. The storage chip should be non-volatile.
It is recommended to have 20000 registration card permissions and 100000 offline storage records, which can meet the storage capacity requirements of most customers and facilitate attendance statistics. Be sure to use nonvolatile memory chips such as Flash, so that information will not be lost even if power is lost or impacted. If the RAM+battery mode is adopted, the information may be lost if the battery is dead or loose, or is impacted by current, and the prohibition system may fail.
Recommendation 4: The design of the communication circuit should have a self-test function, which is suitable for the needs of large system networking
The networking of access control controllers usually adopts 485 industrial bus structure. In order to save costs, many manufacturers usually choose max 485 487 or 1487 chips. These chips have weak load capacity, usually 32 devices. If one communication chip in the bus is damaged, the communication of the whole communication line will be affected, And it is impossible to find out which controller's chip is damaged. We recommend to use high-grade communication chips and integrated circuits similar to max3080. This circuit has a self checking function. If the chip is damaged, the system will automatically disconnect the connection to it, so that the control equipment on other buses can communicate normally.
Recommendation 5: The application program should be simple, practical and easy to operate
If the control program is applied, it will undoubtedly increase the cost and time for the engineering company to train customers. Customers who are not easy to master the operation of the software will be angry at the service attitude of the engineering company, which will have a negative impact on collection and order renewal. Customers who do not understand the software are also prone to misoperation, resulting in practical inconvenience. Therefore, we suggest that when choosing the access controller, the engineering company must pay attention to whether the software operation is simple, intuitive and convenient, and one-sided emphasis on powerful functions is not suitable for promotion.
Recommendation 6: It is better to use high-power well-known brand relays, and the output terminal has current feedback protection
The output of the access controller is controlled by the relay. When the controller works, the relay should be opened and closed frequently, and there is an instantaneous current passing through each time. If the capacity of the relay is too small, the instantaneous current may exceed the capacity of the relay, which will soon damage the relay. In general, the capacity of the relay should be more than 3 times the peak current of the electric lock. It is recommended to select a relay with 7A rated working current. The output terminal is usually connected to high current inductive equipment such as electric lock, and instantaneous on-off will produce feedback current impact, so the output terminal should be protected by varistor or reverse diode and other components.
Recommendation 7: The input circuit of the card reader needs anti surge and anti misconnection protection
During construction, the engineer often carries out wiring or debugging with electricity, which may cause local short circuit due to accidental negligence, wrong connection of card reader wire or carelessness. 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 entire controller, which needs to be sent back to the manufacturer for maintenance, which may delay the construction period and increase the construction cost. Good protection can ensure that even if the power supply is connected to the data terminal of the card reader, the circuit will not be burned out. Through the anti surge dynamic voltage protection, the normal operation of the controller can be prevented from being affected by the quality problem of the card reader.
Suggestion 8: It is recommended that the engineering company purchase the controller from the manufacturer or the agent designated by the manufacturer
Only by directly looking for the manufacturer or the agent designated by the manufacturer can it be possible or perfect powerful technical services, perfect after-sales services can be guaranteed, and reliable follow-up research and development capabilities can be provided to ensure the continuity and advancement of products. It may be cheaper to buy controllers from other channels, but technical support and after-sales service may not be enough.
Recommendation 9: The manufacturer needs to provide authoritative quality certification
The manufacturer needs to provide the authoritative ISO9001 quality certificate and the product test report of the government quality supervision agency. And pay attention to verify the authenticity of these documents. The quality of products certified and supervised by the corresponding third party will be guaranteed.
