DSSS RF Modem

The RFU-2400 CR is a 2.4 GHz wireless modem that converts serial signals into a radio link, so a host and remote devices can exchange data without a physical cable run. It offers one RS-232 port and one RS-485 port, which makes it suitable for linking existing serial equipment into a wireless network.Built on direct sequence spread spectrum (DSSS) radio technology and the IEEE 802.15.4 standard, the modem operates across 16 channels in the 2405 to 2480 MHz range. It supports Peer-to-Peer mode for full-duplex communication and Broadcast mode for half-duplex multi-point links. Configuration is handled by a fully external switch, and the unit is fitted with surge and ESD protection.Key points for specification:Default transmission power of 11 dBm, rising to 19 dBm maximumReceive sensitivity of -96 dBmPower consumption of 1 W maximumOperating temperature range of -25 ~ +75 °CPlastic housing for DIN-rail mountingApplicationsLow-cost data acquisition between a host and remote sensorsWireless control links where physical wiring is inconvenientSerial-to-wireless bridging for existing RS-232 or RS-485 equipmentMulti-point serial communication using Broadcast mode

The RFU-433 CR is a serial-to-radio modem for the 433 MHz ISM band. It takes data from an RS-232 or RS-485 device and sends it over a wireless link in transparent transmission mode, so engineers can extend serial connections without running cable between the two points. With a line of sight range of up to 500 m at a 9600 bps RF rate, it suits short-to-medium distance links between plant equipment, buildings or remote sensors.Reliability in difficult radio conditions is built around configurable parameters. The RF baud rate can be lowered to 650 bps to improve noise resistance, and 16 RF channels and 8 Group IDs let adjacent networks be kept apart. Most settings are made with the rotary and DIP switches rather than software, which makes a like-for-like replacement straightforward.The modem includes a PA switch to increase RF output, with a default of 10 dBm and a maximum of 19 dBm. Serial ports support 1200 to 115200 bps, N81, E81 and O81 data formats, and photocoupler isolation of 2500 Vrms on the serial side. The unit is rated for -25 ~ +75 °C operation and mounts on a DIN rail.ApplicationsWireless serial links between RS-232 or RS-485 devicesData transfer in harsh or electrically noisy environments at reduced RF baud ratesCo-located wireless networks that need separate channels or Group IDsReplacement of an existing RFU-433 modem with minimal reconfiguration

The SST-900B CR is a 900 MHz RF modem that extends a serial RS-232 or RS-485 link without cabling. It suits data acquisition and control schemes where a host must communicate with remote sensors, and where running cable is impractical or costly.The modem operates across 902-928 MHz with 16 RF channels, and each channel can be assigned one of 16 group IDs, so several networks can share the same site. Half-duplex operation runs at up to 115200 bps, with a typical line-of-sight range of 700 m. Both peer-to-peer and multi-point topologies are supported.An internal self-tuner ASIC on the RS-485 port and a configuration switch simplify setup. The unit accepts +10 VDC to +30 VDC, draws 0.48 W, and is designed for DIN-rail mounting in a plastic housing rated for -25 to +75 °C.ApplicationsData acquisition between a host and remote sensorsRemote control applicationsInstallations where cable wiring is inconvenient

tRFU-2400 CR is a 2.4 GHz spread spectrum RF modem that acts as a wireless bridge between serial and wireless formats. It offers one port that can be set to RS-232, RS-422 or RS-485, making it suited to replacing a physical cable run with a radio link between a host and remote serial devices.The modem is based on the IEEE 802.15.4 standard and operates in the ISM band between 2405 and 2480 MHz across 16 channels spaced 5 MHz apart. Peer-to-Peer mode provides full-duplex communication, while Broadcast mode supports half-duplex operation in multi-point networks. Half-duplex links run up to 115200 bps and full-duplex links up to 57600 bps.Hardware configuration is handled through a fully external switch, and surge and ESD protection is included. The unit is DIN-rail mountable and specified for an operating temperature of -25 ~ +75 °C. The manufacturer lists this ordering code for Asia only.ApplicationsWireless bridge converting serial signals to wireless and backLow-cost data acquisition and control between a host and remote sensorsSerial links where physical wire deployment is inconvenient