Widely used. Small size, easy to use. Product Name: 433M 868M Multifunctional Wireless RS485 Bus RF Serial Port UART Transceiver Module DTU for PTZ Camera PLC Modbus RTU Interface: RS485 Working voltage: DC 5V. Working current: 5-40MA. Transmit power: -40~+20dBm Frequency: 433MHz Receive sensitivity: -114dBm Working temperature: -25Celsius~+75Celsius Air-to-ground transmission distance: 500M Dimensions (without antenna): 58.5x30x13.8mm The baud rate configured in AT mode is fixed as: 9600BPS Transparent transmission mode baud rate: 1200 2400, 4800, 9600 (default), 19200; How to use ( equal 2pcs): 1 2PCS, Module 1 and Module 2 send data to each other. 2 3PCS, module 1 sends data, module 2 acts as a repeater (multiple repeaters can be used), and module 3 receives data; delay sending and receiving distance. 3 equal 3PCS, one as the master device and the other as the slave device. The way they work as well as a wired RS485 bus. The master device sends data, and both slave devices receive data. Any slave device sends data, and the master device and other slave devices can receive it. Previously only one device (master or slave) was allowed to send data. Application:PTZ Camera; Modbus modbus temperature sensor; LED Controller; RS485 Relay; Remote control, remote measurement system;Wireless meter ;Smart Home,Home Automation ,Wiser Home;Access control ;Identification system ;Data collection;IT household appliance ;Intelligence household appliance;Baby monitoring system; Colour:green + black Material:PCB board + electronic accessories Package Contents: 2 x RS485 Wireless Transceiver Only the above package content, other products are not included. Note: Light 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.