Developing a testbed for distributed real-time applications

Fixed priority scheduling is viewed to be a standard technique for the scheduling of tasks in real-time systems on uni-processors. There are, however, also communication protocols which are based upon fixed priority scheduling. This paper discusses a testbed which has been constructed using embedded controller boards connected via a CANbus. The testbed supports experimentation with distributed real-time systems using both the Ada-95 and C programming languages. Support is provided for a higher level CAN communication protocol by a set of interface routines, and for multi-tasking on a single processor through the provision of a kernel of routines based upon the Pthread standards. Results are provided which suggest that the testbed can allow the deterministic scheduling of both tasks and communications, thus facilitating experimentation with distributed real-time systems. Copyright (C) 1999 IFAC.