The place of digital backup in the direct digital control system

The key to the success of direct digital control on large industrial processes lies in its flexibility in implementing everyday process control problems as well as advanced control at lower overall system cost. Control concepts for continuous processes use the computing, monitoring, information storage and analytical ability of the direct digital control computer. In the batch or discontinuous process the computer's logic capability is emphasized. To perform batching operations, a comprehensive logic system is necessary. Implementation of such a system using digital techniques provides many advantages over implementation using analog equipment with auxiliary digital logic circuits.