UNIVERSAL SCHEME OF INPUT/OUTPUT REDUNDANCY IN A PROCESS CONTROL SYSTEM

摘要

A master controller has a slave input/output processor (IOP) and a backup slave IOP, both loaded with the same data base, the backup slave IOP eavesdropping on all communications from the controller to the slave IOP to update its data base. Detection by either IOP of a fault is communicated to the other, the IOPs then failover. Finally, the controller acknowledges that the backup slave IOP is now operating as the primary source to the device. The failover occurs without any loss of communications within the control system and is transparent to the control system.