Suggestion One: Choose the access control controller with anti-panic and self-test circuit design
If the access control controller freezes, will make the user open or shut the door, to the customer to bring great inconvenience, but also increase the maintenance of the contractor and maintenance costs. Access controller must be installed reset chip or select with reset function of the CPU, the general 51 series of CPUs do not have the Reset function, need to add the reset chip. At the same time, must have the self-test function, if the circuit because of interference or abnormal conditions, the system can self-test and in an instant from the start.
Recommendation II: With three-level lightning protection circuit design of the access control controller
Because the access control controller's communication line is distributed, susceptible to the invasion of induction thunder, so access controller must be designed to prevent thunder. We recommend the use of three-level lightning protection design, through the discharge tube will be lightning generated by the large current and high voltage released, in the inductance and resistance circuit to clamp into the circuit of the current and voltage. The residual current and voltage are then released at high speed through the TVs high speed discharge tube before it damages the circuit. The Lightning Protection index requires that the 4000V induction Ray has no damage to the equipment for 50 consecutive times. High lightning protection indicators, equipment, surge resistance, anti-static capacity will be correspondingly high. Some products advertise themselves also have 1500V lightning protection ability, in fact, this indicator is all the chip itself, do not have the ability to prevent lightning and surge.
Recommendation three: Registration Card Authority reserves to be large, offline record storage is also large enough, memory chips need to use nonvolatile memory chip.
The proposed registration card permissions need to reach 20,000, offline storage records to reach 100,000 best, this can be suitable for the vast majority of customers storage capacity requirements, convenient attendance statistics. Be sure to adopt nonvolatile memory chips such as flash, and the information will not be lost without power or shock. If you use the ram+ battery mode, if the battery is not electric or loose, or by the current impact information is likely to be lost, the system may fail.