Radio

Motorola RNet radios were the wireless modem radios used for communication in the FIRST Robotics Competition from 1993 with the IFI Control System using a custom version of the Ewave SCREAMER422 until the introduction of the cRIO control system and wi-fi communications in 2009. Rnet radios establish a wireless serial communications link similar to a dial-up modem but over-the-air instead of phone lines.

In the 1990s, teams would be supplied RNets in the kit of parts, but these were collected before the beginning of competition and teams in the pits were required to use a tether cable and tether adaptor, a 9-pin serial cable with a null-modem adaptor inserted to swap over the transmit and receive lines to connect the driver station to the robot controller - this also functioned as a wired tether outside of competition. Teams would be given a radio on the same frequency as the one positioned in their driver station to plug into their robot for the match.

In the era of the IFI Control System, competition-legal radios were given to teams which would work in conjunction with the robot controller and operator interface's team number settings to link together. At competition, operator-side radios were affixed to the inside of the driver station "glass". Tether cables for robot control were still required in the pits and a serial tether cable had to be used to connect a PC to the robot controller for uploading and debugging code. IFI offered a pair of Ewave Screamer wireless transceivers to upload and debug code wirelessly. A larger style of radio was used in 2007 and 2008.

Gallery

• Additional photos on the FRC Archive
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  A pair of the older metal-case RNet radios [1]
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  The tether cable and adaptor setup [2]
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  An IFI-cased modem radio [3]
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  IFI radios hanging on the driver station wall [4]