Long-distance wireless transmission (up to 500 meters in open area, 10kbps baud rate in the air). Operating frequency range (433 - 458.5MHz, up to 255 communication channels). Maximum 100mW (20dBm) transmit power (10 levels of power can be set). Built-in MCU, use serial port to communicate with external devices. Send 31 bytes at a time. The module supports one-to-one, one-to-many transparent transmission communication through ID setting. Changing the baud rate of a different serial port will synchronously change the rate at which data is sent over the air (10kbps-100kbps). Set the 'critical three minutes': the module can send and receive data normally within three minutes of power-on. You can send the AT command 'AT+ENABLE=1' to make the module enter AT state for parameter setting. This reserved word is only valid within these three minutes. After more than three minutes, AT mode cannot be entered; the device will only send and receive data, and 'AT+ENABLE=1' will be transmitted as regular data with no reserved commands available. 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. Transmit power: -40 to +20dBm. Receiver sensitivity: -114dBm. Operating temperature: -25°C to +75°C. Transparent transmission mode baud rates: 1200, 2400, 4800, 9600 (default), 19200. Open ground transmission distance: 500M. Size (without antenna): 74 x 24 x 16mm. Recommend using 2 or more units: With 2 units, Module 1 and Module 2 can send data to each other. With 3 or more units, one acts as master device, others as slave devices. Operation is similar to wired RS485 bus. Master device transmits data, all slave devices receive. Any slave device can transmit data, which is received by the master and other slaves. Only one device (master or slave) can transmit at a time. Applications: IP PTZ Camera, Modbus temperature sensor, LED Controller, RS485 Relay, Remote control, remote measurement system, Wireless meter, Smart Home, Home Automation, Access control, Smart meter. Color: Blue. Material: Plastic + Metal. Package Contents: 2 x 433M-458M VHF/UHF Radio Modem RS485 Transceiver (With shell). Only the above package content is included; other items not included. Note: Light and different displays may cause the color of the item in the picture to differ slightly from the real thing. Measurement allowance: +/- 1-3cm.