1. Long-distance wireless transmission (up to 500m in open area, 10kbps rate in the air). 2. Operating frequency range (433 - 458.5MHz, up to 255 communication channels). Maximum 100mW (20dBm) transmit 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 supports one-to-one, one-to-many transparent transmission communication through ID setting. Changing the rate of a different serial port will 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 command 'AT+ENABLE=1' to make the module enter AT mode for parameter setting. This command is only recognized within the first three minutes. After three minutes, the module will no longer accept AT commands and will only send and receive data; any further 'AT+ENABLE=1' input will be treated as regular data transmission. 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 rates: 1200, 2400, 4800, 9600 (default), 19200 bps Open ground transmission distance: 500m Size (without antenna): 74 x 24 x 16mm Recommend using two or more units How to use (with two or more units): - For 2 units: Module 1 and Module 2 send data to each other. - For 3 or more units: One acts as the master device, others as slave devices. They operate similarly to a wired RS485 bus. The master transmits data and all slaves receive it. Any slave 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 and remote measurement systems Wireless meter reading 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 are not included. Note: Lighting and display differences may cause slight color variations between the image and the actual item. Measurement error allowance is +/- 1-3cm.