The RFU-920 is an RS-232/485 to 920 MHz radio modem that can be used to convert data from RS-232/485 devices into RF messages and then transmit them in transparent mode over the 920 MHz ISM band. The RFU-920 provides a maximum line-of-sight (LOS) transmission distance of 500 meters (0.5 kilometers) at an RF baud rate of 125 kbps. In order to minimize the interference that may be encountered in the environment, the RFU-920 offers a variety of RF baud rate configurations from 5 k to 250 kbps to enhance the modem's ability to resist noise and other interference. In addition, users can distinguish and control different RFU-920 networks by setting up to 16 RF channels and group IDs, which helps to avoid the mutual influence of two neighboring RFU-920 networks. Most of the setup parameters can be adjusted using a combination of rotary switches and DIP switches, providing easy system maintenance when the RFU-920 modem needs to be replaced.