The indicator lights are the expressions of the access control controller. You can immediately tell whether the access control controller is happy, sad, angry or joyful. 

Understanding the indicator lights of the access control controller enables you to keep track of the working status and communication status of the access control system at any time, just like the 'expression package' of the controller. During debugging and maintenance, you can clearly see whether the access control controller is functioning properly without always having to go to the management computer to check. The regular indicator lights of the access control controller include the following types: 

(1) The power indicator light is usually labeled as 'POWER'. When this light is on, it indicates that the access control controller is receiving normal power supply. In China, red lights are commonly used, while internationally, green lights are typically employed. Red lights signify faults. 

(2) The main chip operation indicator light, usually labeled as 'CPU', when this light flashes, it indicates that the main chip is operating normally and the clock circuit is functioning properly. 

(3) The card reading indicator light, usually labeled as 'CARD', will turn on briefly when the card is being read, indicating that the card's information has been successfully retrieved. 

(4) The electric lock output indicator light, usually labeled as 'LOCK', will light up when the door is unlocked, indicating that the access control controller has sent out the unlocking signal. 

(5) Communication indicator lights, the common marking is RX/TX. When the lights are on or flashing, it indicates that the communication is working properly. If it is a TCP/IP controller, there are also communication status indicator lights on the network port, usually consisting of two lights, one indicating the receiving status and the other indicating the sending status. 

(6) Alarm indicator light, usually located on the linkage expansion module, corresponding to the connected alarm port. When the light is on, it indicates that an alarm signal has been input. 

By observing these status lights, one can generally understand the working status of the access control system. For example: when reading the card but not unlocking, we can first check if the corresponding 'lock' light is on when reading the card. If the 'lock' light is on but no unlocking occurs, it indicates that the lock wire is wrongly connected, or there are problems with the electric lock itself or its installation. We should start troubleshooting from the electric lock output of the access control controller. If the 'lock' light is not on when reading the card, then don't wrongly blame the electric lock. We should look for problems from the settings and authorization of the access control controller as well as the card reader. Then, check if the 'card' light flashes when reading the card. If it doesn't flash, it means there is a problem with the card reader or the card reader circuit. If the light is on when reading the card, then check the settings of the access control controller. So, don't underestimate these lights. There is still some knowledge involved in them. Understanding it is like having a divine eye, allowing you to penetrate the internal operation of the entire access control system.