The 4-way Modbus relay module is equipped with a mature and stable 8-bit MCU and RS232 level communication chip. By using the standard MODBUS RTU RS232 communication protocol, it can realize 4-channel input signal detection and 4-channel relay output, which can be used for digital detection or power control occasions. Communication protocol: supports standard Modbus RTU protocol. Communication interface: Supports RS232/TTL UART interface. Communication rate: 4800/9600/19200, default 9600bps, supports power-off saving. 1. Built-in mature and stable 8-bit MCU and MAX3232 level conversion chip; 2. Communication protocol: supports standard Modbus RTU protocol; 3. Communication interface: supports RS232/TTL UART interface; 4. Communication rate: 4800/9600/19200, default 9600bps, supports power-off saving; 5. Optocoupler input signal range: DC3.3-24V (this input cannot be used for relay control); 6. Output signal: relay switch signal, supports manual, flash-off, flash-off mode, the delay base of flash-off/flash-off is 0.1S, and the maximum flash-off/flash-off time can be set to 0xFFFF*0.1S=6553.5 S; 7. Device address: range 1-255, default 255, supports power-off saving; 8. The speed, input signal, relay status, and device address can be read using software/commands; 9. Built-in 4-way 5V, 10A/250V AC 10A/30V DC relays, which can be pulled in 100,000 times continuously, with diode diversion protection and short response time; 10. Built-in relay switch indicator light 11. Power supply voltage: DC7-24V Size: 93 x 87mm Material: PCB color: green Package contents: 1 x Relay Module Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture to be a little different from the real thing. The allowed measurement error is +/- 1-3cm.