A Distributed Feedback System for Rapid Stabilization of Arbitrary Process Variables

Abstract

In large process control systems it frequently becomes desirable to establish feedback relationships that were not anticipated during the design phase of the project. The "Generic Lock" architecture discussed in this paper makes it possible for system operators to implement new feedback loops between arbitrary process variables quickly and with no disturbance to the underlying control system. Any available process variables may be selected for the input and output of the loops so created, regardless of their physical or logical separation. The system allows multiple user interface points distributed through the control system while ensuring consistency among the feedback loops. This system can be used to quickly prototype and test new control philosophies or to control temporary hardware arrangements without any new software development. It is implemented at the Thomas Jefferson National Accelerator Facility using the Common Device (CDEV) framework on top of the Experimental Physics and Industrial Control System (EPICS). This paper discusses the architecture, implementation, and early usage of the system.