Microcomputer based distributed control network

#The present invention relates to an automated monitoring and communication system and more particularly relates to a microcomputer based monitoring and communication system having multiple stations each with selected modular control and monitoring units and which utilizes a redundant fiber optic information management network.

#Early automation and control systems for process control applications conventionally utilized large central computer to monitor and control plant operations. While these systems represented an advance in the art, such systems were generally slow, expensive and did not provide the user with adequate flexibility. Further, because the prior art systems utilized a single computer, reliability was a problem as no back-up systems existed.

#Another approach was to install programmable computers at the various stations or at process locations within the plant. These systems are generally termed "distributed" systems. While the use of multiple, programmable controllers does increase productivity, the use of multiple separate computers does not provide a system which interconnects the programmable controllers to form a central facility data acquisition process control network tying the plant together in a controlled network.

#Thus, it will be seen that the present invention provides a modular microprocessor based control system with high reliability and high speed communication through a redundant fiber optics network or highway. The network of the present invention will be more fully understood from the following drawings in which:

#FIG. 1 is a schematic of a typical network configuration;

#FIG. 2 is a schematic of a module enclosure:

#Referring now to the drawings, particularly FIG. 1, the microcomputer based distributor control network of the present invention is generally designated by the numeral 10 and is shown schematically. Referring to FIG. 1, the basic system 10 includes master host computer 12 which is a large main frame microcomputer containing mass or bulk storage devices. A typical host computer would be an IBM Series I. The subhost 14 provides the gateway between the host and the network loop 13 or several network loops. The subhost station 14 is comprised of various system compound modules including at least two network control modules (NCM) 16 interconnected to communicate with one another over a common bus, two communication interface logic modules (CIL) 18, and the necessary fiber optics or coaxial drivers. The abbreviations NCM and CIL will be used throughout to refer to the network control module and the communications interface logic module, respectively. These and other abbreviations are utilized in the interest of brevity and convenience.

#A brief functional overview of the subhost's operation follows and will aid in an understanding of the invention. More detailed discussion of the components and their interrelationship is set forth hereafter in the specification.

#The subhost node or station 14 provides a gateway between the host computer 12 and the network(s) 13. Each NCM, as will be described in greater detail hereafter, includes a 8/16 bit microprocessor offering a high speed multi-protocol device, programmable timer, DMA capability, and selectable memory devices.