A FIELDBUS FOR SAFETY-RELATED REAL-TIME OPERATION SUPPORTING FORWARD RECOVERY FROM REDUNDANT NODES

A concept for a ring-based fieldbus serving both data exchange with process peripherals and between multiple redundant processing nodes is presented. The concept fulfills real-time demands and supports state restoration of error-affected or replaced processing nodes at runtime. Its tight integration into a holistic architecture of a safety-related programmable electronic system features this form of forward recovery without the drawback of inadequately long system response times. A multi-ring connection scheme combines high, scalable reliability and low wiring expenses with an especially simple structure. Communication is performed in discrete intervals and in synchrony with the cyclically organised application processing, leading to a simple and easy-to-model temporal behaviour of the entire system. This eases verification and reduces the cost for safety licensing.