In the debugging and on-site maintenance of access control controllers, the hardware indicator light method is the basic means of quickly locating faults. Without the need for complex software operations, by observing the status of various LED indicators on the motherboard and combining them with sound assisted judgment, it is possible to preliminarily distinguish between major types of faults such as power supply, card reading, relay output, communication, hardware errors, etc., narrow down the scope of investigation, and then cooperate with management software for in-depth confirmation, greatly improving on-site maintenance efficiency.

1. Power indicator light POWER, CPU running indicator light

After powering on, observe that the POWER power light should remain constantly on; The CPU indicator light keeps flashing regularly, indicating that the controller has started working normally.

Fault phenomenon: POWER light not on → Check if the power adapter output, wiring terminals are loose, and fuses are blown. Use a multimeter to measure and confirm if the DC12V power supply is in place.

Fault phenomenon: The POWER light is on, but the CPU light is always on/not flashing at all → The controller crashes, the power supply voltage is insufficient, or the main control chip is abnormal. You can try to power off and restart; If the restart is ineffective, suspect hardware damage and return to the factory for testing.

2. Card reading indicator light CARD

Observe the status of the CARD light when swiping the card to determine if the data link between the card reader and the controller is unobstructed.

Normal state: When flashing valid/invalid cards, the CARD light flashes synchronously, indicating that the card reading signal has been successfully transmitted to the access control controller motherboard.

Fault phenomenon: The card reader beeps when swiping the card, but the CARD light on the controller does not respond at all: it is most likely that the Weigen wiring is reversed or disconnected; It is also possible that the card reader protocol does not match, the reading head is damaged, or the controller's Wiegand input port is burned. It is necessary to conduct a segmented investigation of the circuit and equipment.

3. Relay output indicator light (exit button)

Press the exit button, observe the relay indicator light, and pay attention to whether the motherboard relay makes a "click" sound to determine if the controller's door opening output circuit is working properly.

Normal state: Press the button, the indicator light will turn on, accompanied by a "click" sound from the relay, indicating that the controller has output a door opening signal.

Fault phenomenon: When pressing the button, the light does not light up and there is no sound. The wiring of the exit button is broken, the button is damaged, or the controller relay circuit is faulty.

Additional reminder: If the indicator light and sound are normal, but the door does not open, focus on checking the electric lock, lock body power supply, and lock wiring. The fault is not on the access control controller motherboard.

4. Communication indicator lights TX and RX (distinguish between TCP network type and RS485 bus type controllers)

Observe the TX and RX indicator lights when performing communication operations such as software connection, uploading and downloading parameters:

TCP network controller: The RX (Link) port Link light is constantly on, indicating that the physical link of the network cable is basically connected; The TX light flashing indicates that the device is sending and receiving network packets. The Link light is not on, priority should be given to checking the network cable, crystal head, and switch ports.

RS485 bus controller: RX light flashing=controller receives external data; TX light flashing=controller sends data outward. The two lights are completely flicker free, indicating that there is no data exchange between the computer and the controller. Check if the 485 converter, A/B line connections are reversed, and if there is a short circuit or open circuit in the line.

5. Fault indicator light ERR

The ERR light remains off in a normal state; Once the ERR light flashes or stays on, it indicates that the controller has detected an internal abnormality.

Processing: Log in to the access control management software, perform controller detection function, read fault details, and check whether it is a memory abnormality, external short circuit, or parameter disorder. You can try shutting down and restarting; Repeatedly reporting errors, it is necessary to backup parameters and format the controller, but the fault cannot be eliminated. Contact the manufacturer's technical support to resolve the hardware issue.

6. Video access control controller network port RJ45 indicator light

When the video access control controller is powered on and connected to the network cable, pinging the device or accessing the device background, the two status indicators of the RJ45 network port should flash alternately.

The network port light is completely off: the network cable is damaged, the crystal head is poorly crimped, and the switch port is faulty.

The light stays on without flashing: The physical link is connected, but no data traffic is generated. Check the IP address, subnet mask, and firewall settings.

7. RS485 active converter indicator light

When the computer issues instructions to operate the access control equipment, observe whether the indicator light of the 485 active converter flashes.

The converter light is completely flicker free: there is an error in the configuration of the computer serial port, abnormal power supply to the converter, and hardware damage to the USB 485 converter.  

The indicator light flashes randomly in idle state: there is line interference and short circuit of 485 bus A/B. Check the wiring and add shielding grounding treatment.

Supporting supplement: Practical suggestions after troubleshooting the indicator lights

1. The indicator lights can only be used for preliminary fault location, and some hidden fault indicator lights perform completely normally and must be coordinated with access control software

Real time monitoring and controller detection function, reading event logs and hardware status for further confirmation.

2. When changing hardware wiring, be sure to disconnect the controller power first to avoid burning the motherboard ports due to hot plugging.

3. If the power light flashes or the adapter heats up severely, immediately turn off the power and check if there is a short circuit in the backend to prevent burning of the controller.

If multiple 485 devices have abnormal communication, priority should be given to checking whether the bus terminal resistance is properly configured to reduce signal reflection interference.