20dBm 433MHz RS485 Wireless Modem

Dimensions: 74 × 24 × 16 mm (excluding antenna); operating voltage: 4.5–5.5 V DC. RS485 interface compliant with 5 V logic (pins: 5 V, GND, A+, B−). Frequency coverage: 433–458.5 MHz — fully aligned with UK/EU 433 MHz SRD band allocations. Channel count: up to 255 selectable frequencies. Transmit power: adjustable from −40 dBm to +20 dBm (100 mW) in 10 steps. Receiver sensitivity: −114 dBm ensures reliable weak-signal reception in noisy industrial settings. Air data rate dynamically scales between 10 and 100 kbps, locked to UART baud rate (1200, 2400, 4800, 9600 default, 19200 bps). Max packet payload: 31 bytes. Onboard MCU handles serial framing and channel/power management. Transparent transmission mode is persistent after initial 3-minute AT window (AT+ENABLE=1 required to enter configuration). Temperature range: −25 °C to +75 °C. Housing: durable plastic enclosure with integrated metal shielding elements. For two units: full-duplex bidirectional communication. For three or more: configure one master and remaining as slaves — all share same frequency and channel, with device ID used for logical addressing; master sends to all, slaves respond individually — preserving RS485 bus semantics including half-duplex timing and listen-before-talk discipline. Deployed in real-world applications including wireless IP PTZ camera pan/tilt/zoom control, distributed Modbus temperature and humidity sensor arrays, programmable LED signage controllers, RS485-based relay modules for HVAC or lighting, remote telemetry for water/gas meters, home automation backbones linking thermostats and actuators, electronic access control panels, and EU-compliant smart electricity meters — all leveraging robust 433 MHz propagation characteristics indoors and across urban terrain.