Wireless Long-Distance Transmission: Up to 500 meters in an open area, with a 10 kbps air baud rate. Operating Frequency Range: 433 - 458.5 MHz, with up to 255 communication channels. Maximum 100mW (20dBm) power (10 power levels can be set). Built-in MCU: Uses a serial port to communicate with external devices. Sends 31 bytes at a time. Module Support: The module can support one-to-one, one-to-many transparent transmission communication through ID settings. Changing the transmission rate for another serial port will synchronously change the speed at which data is sent over the air (10 kbps-100 kbps). Set 'Critical Three Minutes': The module can send and receive data normally within three minutes after startup. You can send the AT command 'AT+ENABLE=1' to make the module enter the AT command state for parameter setting. This is the only reserved word within these three minutes. After more than three minutes, you will not be able to enter AT command mode; you can only send and receive data. 'AT+ENABLE=1' will also be sent out as data, with no reserved words at that time. Product Name: VHF/UHF Radio Modem RS485 Wireless Transceiver 20DBM 433mhz Transmitter and Receiver Working Voltage: 4.5V-5.5V; Interface: RS485 (5V GND A+ B-) Frequency: 433MHz Power: -40~+20dBm; Receiver Sensitivity: -114dBm; Operating Temperature: -25 Celsius~+75 Celsius; Transparent Transmission Mode Transmission Rate: 1200, 2400, 4800, 9600 (default), 19200; Open Field Transmission Distance: 500M Size (without antenna): 74 x 24 x 16 mm Recommend purchasing more than 2pcs. How to Use (more than = 2 pcs): 1/2PCS: Module 1 and Module 2 send data to each other. 2 more than = 3PCS: One as the master unit, the others as slave units. They function similarly to a wired RS485 bus. The master unit sends data, and all slave units receive it. When all slave units send data, the master unit and other slave units can receive it. At any time, only one unit (master or slave) is allowed to transmit data. Application: IP PTZ Camera Modbus Temperature Sensor LED Controller R4D3C32 N4D8B08 N4D8C12 RS485 Relay Remote Control, Remote Measurement System; Wireless Meter; Smart Home, Home Automation, Smarter Home; Access Control; Smart Meter Color: Blue Material: Plastic + Metal Package Contents: 2 * 433M-458M VHF/UHF Radio Modem RS485 Transceiver (with shell) (Only the above package content is included. Other products are not.) (Note: Light and different displays may cause the color of the item in the picture to differ slightly from the actual item. The allowed measurement error is +/- 1-3 cm.)