THE INTRODUCTION OF PROGRAMMABLE LOGIC CONTROLLERS INTO US NAVY MACHINERY CONTROL-SYSTEMS

Programmable logic controllers (PLCs) have long been used in process a nd manufacturing industries for data acquisition and control. Acquisit ion reform, prompted by the need to reduce the cost of military system s, mandates the use of Commercial Off-the-Shelf (COTS) or modified COT S-based systems and equipment. For shipboard Engineering Control Syste ms (ECS), this has led to the introduction of ruggedized commercial wo rkstations at the supervisory level. The transition to COTS has lagged at the local control level, however, due in part to a perceived lack of COTS equipment which can satisfy the need for highly reliable and r obust real-time controllers. This has typically resulted in custom and proprietary hardware and software at the local level. This paper revi ews the top-level architecture of a typical ECS for a surface combatan t and traces the migration from a past generation system, represented by the DDG 51 Class Machinery Control System, to a potential current g eneration system which utilizes PLCs as a COTS technology. The technol ogy and architecture found in current generation PLCs is briefly revie wed as well as the typical application of PLCs for process control and commercial marine machinery control. Finally, the various factors inf luencing the cost of a shipboard ECS are discussed, with emphasis plac ed on how a COTS system has a positive influence on all of the cost fa ctors. The paper concludes with a description of the potential current generation COTS ECS and a brief discussion of next generation advance s.