RFU-433 is a radio modem that allows extending the RS-232/RS-485 line over the radio interface and transmitting data in the transparent mode using the 433 MHz frequency band.
Although, the baud rate of 433 MHz radio modems is lower than that of 2.4 GHz technology, the 433 MHz band provides the advantage of long-distance communication. Thus, this frequency is appropriate, if small amount of data is transmitted or if there is a large time interval between two long-distance transmissions, for instance, when monitoring the environmental parameters or monitoring and managing solar panels, etc.
RFU-433 provides the maximum transmission distance of 500 m in the line-of-sight environment at the transmission baud rate of 9600 bps and the standard transmission power of 10 dBm. In the settings, the power can be increased up to 19 dBm, thus, increasing the distance or the transmission baud rate (so, the transmission distance can reach 1 km).
Sometimes, in order to overcome the noise that can occur in a harsh environment, the baud rate can be reduced, for instance, RFU-433 allows configuring the minimum transmission baud rate of 650 bps.
To adjust the required radio frequency channel, the transmission power and the time interval, use a special utility program when connected to a COM port of a device.
Selecting baud rate of COM ports and radio interfaces, data formats, group IDs, as well as operation modes is performed using the Rotary and DIP switches, thereby providing easy system maintenance if RFU-433 modem needs to be replaced.
Radio frequency channels and group IDs can be configured, in order to avoid interferences that occur when two RFU-433 networks work nearby. 16 radio frequency channels and 8 group IDs can be set up to separate and manage various 433 MHz networks.
Fig. 1 One -to-One transmission
Fig. 2 One-to-Many transmission
Fig. 3 Repeater mode