Patent ID: 7660915

Claim:
A process control system for communications in a process control network having a plurality of devices in communication using a bus, the process control system comprising: a primary redundant device communicatively linked to the bus and programmed to perform fault detection; a secondary redundant device communicatively linked to the bus and programmed to detect a primary redundant device fault, wherein the secondary redundant device, upon detecting the primary redundant device fault, publishes a primary redundant device fault message on the bus, and wherein the secondary redundant device is capable of detecting secondary redundant device faults, and wherein a primary redundant device no fault message is published on the bus where no fault is detected in the primary redundant device; and a controller communicatively linked to the bus and including a controller processor programmed to cause the primary redundant device to perform fault detection by publishing a primary fault detect order message on the bus, and to process messages published on the bus, wherein the controller deactivates the primary redundant device responsive to the primary redundant device fault message, and wherein a secondary fault detect order message published by the controller responsive to the primary redundant device no fault message causes the secondary redundant device to perform fault detection.