1. MCU and MAX485 level conversion and stable on-board 2. Communication Protocol: Supports standard Modbus RTU protocol 3. Communication Interface: Supports UART RS485/TTL interface 4. Communication Baud Rate: 4800/9600/19200, default 9600, supports power-off 5. Optocoupler input signal: DC3.3-30V (this input cannot be used for relay control) 6. Output signal: relay switching signal, supports manual, flash, flash mode, flash/flash delay base is 0.1s, the longest flash/flash time can be set to 0xFFFF*0.1S = 6553.5S 7. Device Address: 1-255, default 255, supports power-off saving 8. Baud rate, input signal, relay status, device address can be via software/command 9. Built-in 4 relays 5V, 10A/250V AC 10A/30V DC, can be activated 100,000 times continuously, with diode flow protection and short response time 10. On-board relay switching indicator 11. Power Supply Voltage: DC7-24V, supports DC socket/5.08mm power connection, with reverse connection protection input Type: Switching Relay Module Rated Voltage: 4 Channels Color: Blue Material: PCB Package Contents: 1 x Relay Module Only the above package content, other products are not included. Note: Light photography and different displays may cause the color of the item in the picture to be slightly different from the real one. The allowed measurement error is +/- 1-3 cm.