Abstract: A method for use by a primary device associated with a secondary device of a redundant pair, the primary device issuing a synchronization request to its control database causing the primary device to send a tracked memory file storage of the primary device to the secondary device to update the secondary device control database and to periodically send on request of the primary device the cached changes made in the primary device to the secondary device to update the secondary device control database. The secondary device using the updated control database to identify communications connections and paths to I/O modules and peer devices assigned to the secondary device and to perform diagnostic testing of the communications connections and paths identified by the interrogation and send diagnostic messages upon detection of faults in the communication connections and paths identified.

Abstract: A method is disclosed for using an alternate communication path to send and receive data between a first network node and a second network node. The method includes establishing a first communication path between the first network node and the second network node that sends and receives data between the first network node and second network node and a second communication path between the first network node and the second network node that sends and receives data between the first network node and second network node. A diagnostic program tests the first and second communication paths for network failures causing the alternate network path to send and receive data between the first network node and second network node when a network failure in the first and second communication paths is detected and alerting a technician of the failure and that the first and second communication paths need repair. The first and second communication paths returning to normal operation upon the repair of the failure.

Abstract: A method for use by a primary device associated with a secondary device of a redundant pair, the primary device issuing a synchronization request to its control database causing the primary device to send a tracked memory file storage of the primary device to the secondary device to update the secondary device control database and to periodically send on request of the primary device the cached changes made in the primary device to the secondary device to update the secondary device control database. The secondary device using the updated control database to identify communications connections and paths to I/O modules and peer devices assigned to the secondary device and to perform diagnostic testing of the communications connections and paths identified by the interrogation and send diagnostic messages upon detection of faults in the communication connections and paths identified.