DISTRIBUTED CONTROL SYSTEM INCLUDING A COMPACT EASILY-EXTENSIBLE AND SERVICEABLE FIELD CONTROLLER

摘要

A field controller for use in a distributed control system including an area controller and atleast one field controller. The field controller manages at least one controlled device in an industrialprocess operation. The field controller comprises a processor module segment through which it cancontrol a selected number of devices, and it may also include one or more expansion module segmentsto enable it to control a larger number of controlled devices. The processor module segment includesa processor module and at least one local interface module for interfacing to a controlled device, andthe expansion module segment includes interface modules for interfacing to other controlled devices.In the processor module segment, the processor module and said local interface module areinterconnected by a bus segment, which is also connected to an upstream off-module connector.Each expansion module segment includes at least one interface module, and also includes adownstream off-module connector and an upstream off-module connector, which are interconnectedby a bus segment. The downstream off-module connector of each expansion module segment isadapted to mate with the upstream off-module connector of the processor module segment and ofother expansion module segment, so as to facilitate the interconnection of the processor modulesegment and a sequence of expansion module segments by establishing a unitary multi-drop buscomprising the processor module's bus segment and the bus segments of expansion module in thesequence. The processor module controls each controlled device through the respective localinterface module or expansion interface module connected thereto. The processor module segmentand each expansion module segment are each mounted in a housing segment which is configured toform a unitary housing when they are interconnected.