1. Long-distance wireless mission (up to 500 meters in open area , 10kbps baud rate in the air ). 2. Operating frequency range ( 433 - 458.5MHz , up to 255 communication channels). Maximum 100mW ( 20dBm ) mit power ( 10 levels of power can be set ). 3. Built-in MCU, use serial port to communicate with external devices. Send 31 bytes at a time. 4. The module can support one-to-one, one-to-many parent mission communication through ID setting Changing the baud rate of a different serial port synchronously change the rate at which data is sent over the air. ( 10kbps-100kbps) 5. Set the ''critical three minutes''. The module can send and receive data normally within three minutes of power-on. You can send the AT '' AT+ENABLE=1 '' to make the module enter the AT state for parameter setting. There is only this reserved word in these three minutes. After more than three minutes, you not be to enter the AT mode, you can only send and receive data, '' AT+ENABLE=1'' also be sent out as data, there are no reserved words at this time. Product Name: VHF/UHF Radio Modem RS485 Wireless ceiver 20DBM 433mhz mitter and Receiver Working voltage: 4.5V-5.5V; Interface : RS485(5V GND A+ B-) Frequency: 433MHz mit power: -40~+20dBm; Receiver sensitivity: -114dBm; Operating temperature: -25 Celsius~+75 Celsius; parent mission mode baud rate :1200 2400,4800,9600(Default),19200; Open ground mission distance : 500M Size(without antenna): 74 x 24 x 16mm Recommend to than 2pcs!!! How to use (more than the =2pcs): 1/2PCS,Module 1 and Module 2 send data to each other. 2 more than the =3PCS,One as master device, the other as be as slave device. the way they work as well as wired RS485 bus. Masterdevice mit data, Slave devices all receive data.Any slave device mit data, master device and the other slave devices can receive .When ever only allowed one device (master or s