A low-cost fail-safe circuit for fault-tolerant control systems

Commercially available fault-tolerant control systems use high-cost multiprocessor architectures. The circuit we introduce, called RCMP, is the fundamental piece of a strategy intended to add fault-tolerance to industrial control systems using standard personal computers. The strategy is to construct a multiprocessor system to be able to vote on the computation partial results by interconnecting N personal computers. The RCMP is the interface between each computer and the communication channel, and it also performs the voting and the transmission of the obtained result. The RCMP presents a duplicated architecture for fail-safe behaviour and a duplicated communication channel to avoid the single point of failure that a single channel would represent. At the implementation level the RCMP is a PC/XT bus card based on a 8 bit microcontroller that interfaces each computer with a duplicated CAN bus