This base-version USB Relay Module is an industrial-grade control board for automation/PLC projects. Supporting Modbus RTU and USB/TTL interfaces, it features DIN rail mounting for reliable remote control. Built with components, it offers stable performance and strong anti-interference. Modbus RTU enables control and flexible networking, while USB/TTL connectivity supports easy secondary development. Widely used in industrial automation, smart homes, and power management. It enables remote equipment control and smart system integration, ideal for both professional and DIY projects. Plug-and-play via USB (power + communication). Includes USB cable, wires, and screwdriver for immediate use. Clear terminals and modular design simplify wiring, expansion, and maintenance. Rigorously tested for reliability, it operates stably from -20℃ to 70℃. Comes with manuals, open-source code, and reliable after-sales support, ensuring a worry-free user experience. Color: As Shown Material: PCB+Metal Package Contents: 1 * B relay base 2 * connecting wires 1 * screwdriver Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.