4‑Channel Relay Module 12V High Accuracy Switch Input for RS485/TTL Communication Item Type: 4-Channel Relay Module Relay Communication: Multi-unit network 485 communication, the default communication address is 1, and the user can modify the address by himself Note: IN1-IN4 are used to connect to the switch and read the switch status through 485, not to control the relay output through the input. The switch status of IN1-IN4 needs to be read by the computer every time it is inquired, and data cannot be sent to 485 actively. Note: IN1-IN4 cannot be connected to 220V (some buyers will make this mistake) The Wiring Method is as Follows: IN1-GND (default is high level, low level after the switch is turned on) The computer sends instructions to read the switch status. IN2-GND (default is high level, low level after the switch is turned on) the computer sends instructions to read the switch status. IN3-GND (default is high level, low level after the switch is turned on) the computer sends instructions to read the switch status. IN4-GND (default is high level, low level after the switch is turned on) the computer sends instructions to read the switch status. Board Resources: 1. S1 reset button 2. D5 running LED indicator Control instruction into group sharing download 1. 4 relay outputs (one normally open, one normally closed) 2. STM8S103F3 MCU 3. 4 optocoupler isolation relay output 4. 4 relay closed LED indicators 5. Circular DC interface, and terminal DC interface. Convenient power connection (power supply voltage 5V or 12V depends on the voltage of the relay) 6. 4 input interfaces (dry node input, passive input, connected to GND) 7. One RS485 communication interface. 8. A power indicator 9. One user LED light 10. Reset button 11. A SWIM download interface-(STLINK-V2 download program, users can develop the program twice) 1. Connect LED er LED 2. TX RX connects to port 485 and pin header TTL port 3. KEY user button (red button on the left) 4. EN 485 use end 5. IN1 -IN4 input ports are directly connected to the terminals 6.K1 -K4 relay output control 7. SWIM programming program J13 Size: Approx. 76 x 67mm / 3 x 2.6in