Recommendation 1: purchase access control device with anti crash and self checking circuit design.
If the door control controller is dead, the user can not open the door or shut the door, and bring great inconvenience to the customer. At the same time, it also increases the maintenance and maintenance cost of the engineer. The control controller must install the reset chip or select the CPU with the reset function. The general 51 series of CPU is not equipped with the reset function. Install the reset chip. At the same time, we must have self checking function. If the circuit is crashed due to interference or abnormal conditions, the system can self check and start self in an instant.
Recommendation two: access control device with three level lightning protection circuit design.
Because the communication circuit of the access controller is distributed and vulnerable to the invasion of inductive lightning, the access controller must design lightning protection. We propose a three stage lightning protection design, which first releases the large current and high voltage produced by the lightning stroke by the discharge tube, and clamp the current and voltage into the circuit through the inductance and resistance circuit. The residual current and voltage are then released at high speed through the TVS high speed discharge tube before damage to the circuit. The lightning protection index requires 4000V 50 times of induction thunder to damage the equipment. The lightning protection index is high, and the anti surge and anti-static ability of the equipment will be correspondingly high. Some products propagandize themselves also have the ability to prevent lightning from 1500V. In fact, this indicator is all chip itself, and it does not have the ability to prevent lightning and surge at all.
Recommendation three: registration card authority storage capacity is large, offline record storage is also large enough, storage chips need to use non-volatile memory chips.
It is suggested that the registration card authority need to reach 20 thousand, and the offline storage records reach 100 thousand best, which can suit the requirements of the vast majority of the customers' storage capacity and facilitate the attendance statistics. We must use Flash and other non-volatile memory chips, power down or impact information will not be lost. If the RAM+ battery is used, if the battery is not working or loosened, or the current will impact, the information may be lost. The access control system may fail.
Recommendation four: 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 engineer to train the customer. It is not easy for the customer to master the operation of the software and the service attitude of the engineer will have a bad influence on the receivables and continued orders. When choosing access control devices, Cheng Yang must pay attention to whether the operation of software is simple, intuitive and convenient.
Recommendation five: communication circuit design should have self detection function, suitable for large system interconnection needs.
The network of access control controllers usually uses the 485 industrial bus structure, usually many manufacturers choose max485487 or 1487 chips from cost saving. These chips are weak in load capacity and usually have the maximum load capacity of 32 devices, and if a communication chip is damaged in the bus, the entire communication line will be affected. Communication, and unable to find out which chip of the controller is damaged. We recommend the use of max3080 like high-end communications chips and integrated circuits. The circuit has self checking function. If the chip is damaged, the system will automatically disconnect its connection, so that the control devices on other buses can communicate normally.
Recommendation six: suitable for high-power brand relay, and output current feedback protection.
The output of access controller is controlled by relay. When the controller works, the relay should be frequently opened and closed, and there will be a transient current passing through each opening and closing. If the capacity of the relay is too small, the instantaneous current may exceed the capacity of the relay and 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 use 7A relay with rated current. The output terminal is usually an electrical inductive device with a large current such as a lock. The instantaneous interruption will produce the impact of the feedback current, so the output terminal should be protected by a varistor or a reverse diode.
Recommendation seven: suggest that the manufacturer should purchase the manufacturer or manufacturer appointed by the controller.
Recommendation eight: reader input circuit needs surge protection and error protection.
When the contractor is in construction, it is often charged for wiring or debugging. It may be accidental, misread the card reader line or accidentally cause a local short circuit. If there is no surge prevention and fault protection protection, it is easy to burn down the central processing chip, cause the failure of the whole controller and need to be sent back to the factory maintenance, which may delay the time of work and improve the construction cost. Good protection can make the power supply do not burn up the circuit even in the card reader data end. By preventing surge dynamic voltage protection, it can avoid the controller's normal operation because of the reader quality problem.
Only directly find the manufacturers or manufacturers designated agents to buy the possible or perfect strong technical services, perfect after-sales service is guaranteed, and have reliable follow-up research and development ability, to ensure that the product has continuity and advanced. Buying a controller from other sources may have a lower price, but technical support and after sales service may not be enough.
Recommendation nine: manufacturers need to provide authoritative quality certification.