1. This design is a relay for industrial application scenarios. It uses Modbus RTU protocol control and 485 signal as the transmission mode. It supports multiple devices controlled by the same host. It can be well applied to industrial automation. With ABS shell and rail buckle, it can be better used in actual environment. 3. Wiring instructions: The relay can be assigned an address in the 485 bus, ranging from 1-255. The corresponding instructions can be sent for the address of the relay, so that the relay receiving the instruction can open and close any controlled circuit. 2. The board is equipped with and stable 8bit MCU and SP3485 level conversion chip. 4. Note: When the relay is energized, the COM terminal and the NO terminal are connected and disconnected from the NC terminal. That is, load 1 works and load 2 does not work. When the relay is not energized or not connected to the power supply, the COM terminal and the NC terminal are connected and disconnected from the NO terminal. That is, load 2 works and load 1 does not work., Weight: 0.42438985435 pounds, Manufacturer: Prterver