CANbus and microcontroller use in the BaBar detector at SLAC

The BaBar collaboration has chosen the Controller Area Network (CAN) bus for its controls and monitoring field bus. In addition, the Motorola MC68HC705X32 microcontroller, which has a CAN interface, was chosen for the standard intelligent device for monitoring boards. This paper describes the CAN system used by BaBar and the embedded software that supports it. The General Monitoring Board (GMB) is presented as a specific example. The GMB is a CAN module that digitizes 32 differential analog signals and has eight bits of bi-directional I/O.