Isolated RS485 Modbus Relay

Dimensions: Not specified in source; weight: not provided; operating voltage: 5–32 V DC (recommended >6 V for stable operation); communication interface: RS485 with selectable 120 Ω termination resistor; protocol: standard Modbus RTU; baud rates: 4800 / 9600 / 19200 / 38400 bps (default 9600, power-off saved); control address range: 1–255; output type: single-pole double-throw (SPDT) relay with COM, NO and NC terminals; isolation: optocoupler-isolated digital input side; housing material: ABS plastic with DIN rail mounting clip. The relay uses a mature 8-bit MCU and SP3485 level conversion chip for reliable RS485 signal handling. It supports multi-drop bus topology — up to 255 units on one RS485 network — enabling scalable industrial automation systems. Each unit is individually addressable, allowing precise remote switching of loads via Modbus commands. Ideal for factory automation, building management, energy monitoring and PLC-integrated control systems where robust serial communication, electrical isolation and DIN-rail deployment are required. The SPDT configuration supports fail-safe or redundant load routing — e.g., activating Load 1 when powered (COM–NO closed), and Load 2 by default when de-energised (COM–NC closed).