4 Channel Relay Module PCB RTU Relays Board Switch RS485 TTL Reverse Prevention Connection Item Type: 4 Channel Relay Module Material: PCB Communication Protocol: Support standard RTU protocol Communication Interface: Support RS485 TTL USRT interface Communication Baud Rate: 4800, 9600, 19200, default 9600bps, support power down save Optocoupler Input Signal Range: DC3.3-30V (This input cannot be used for relay control) Output Signal: Relay switch signal, support manual, flash off, flash break mode, The delay base of flash closing flash breaking is 0.15, and the maximum flash closing flash breaking time can be set as OxFFFF0.1S=65535x0.1S-6553.5S Device Address: Range 1-255, Default 255, support power down save With on board relay switch indicator