Encyclopedia Britannica gives the definition of a relay. Project54 uses 8 relays in order to control the lights and siren on the Lee Motorcycle, in a relay box. This relay box consists of the 8 relays, and a microcontroller that switches the relays on and off. To turn these relays on and off, ASCII commands must be sent to the microcontroller through a DB9 connection. In the motorcycle setup, the relay box has its own IDB box, and the commands are sent through the network from the embedded PC. When a button is pressed on the BikeRelay Project 54 GUI, C++ code interprets that particular button press, and sends the correct ASCII commands to the relay box. The microcontroller interprets these, and turns on or off the corresponding relays.
Above: The relay box used for controlling the motorcycle lights at Project54
For more information on how relays work, visit HowStuffWorks.com.
Devin Mullen