Importance

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Abstract

A process control system includes two digital controllers each capable of exercising direct digital control over the process. One of the controllers is selected to be on-control, the other serving as a backup. A separate data buffer memory connected to both controllers stores the most recent static and dynamic data base of the on-control controller which is transferred to the backup controller. In the event of failure or other loss of service, the backup automatically acquires control with an up-to-date data base resulting in a smooth transition. Provisions are also included to have the backup controller examine the health of the on-control unit before deciding whether or not to accept the data buffer contents thereby reducing the likelihood of corrupted data being fed to the backup.

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First Claim