The Dow Chemical Company

Dow Benelux N.v.

Dale H Schultz

Oscar E Schulze

Roger R Vermeire

Ronny P De Bruijn

Leonardus A Van Weele

Marc L Verboven

Brian G Bell

Joseph Ellison

James H Cullen

James D Allbery, Jr

Stanley R Nunn

James P Ferreira

Richard L Butler

Chiman L Patel

Susan J Johnson

James E Uban

Peter A Troisi

A secure front-end communication system which couples a plurality of actively redundant process control computers to a computer network. The system includes a front end computer which is capable of establishing time limited communication contracts with one or more computer entity on the computer network. Each time limited communication contract is based upon an acceptable response to the transmission of an unpredicable signal from the front end computer, such as an encrypted transformation of a psuedo-random number generated by the front end computer. A security table is used to identify the network entities that are permitted to send write command messages to the process control computers to which the front end computer is connected. The front end computer also includes at least one permissive table which is used to determined whether a write command message from the network entity should be transmitted to the process control computer for which the message was intended.

System and method for determining whether to transmit command to control

An intelligent front-end communication system which is interposed between a plurality of actively redundant process control computers and a computer network. The intelligent front end communication system includes at least one front end computer which is coupled to the computer network, and a serial communication interface which is coupled between the actively redundant process control computers and the front end computer. The serial communication interface transmits sequential sets of dynamic data from the actively redundant process control computers to the front end computer. The front end computer includes a plurality of reflective or shadow memory buffers for storing and time aligning corresponding sets of dynamic data which are asynchronously received from the serial communication interface.

Intelligent process control communication system and method having

Secure communication system for re-establishing time limited

Growing community of inventors

Midland, MI, United States of America

Dale H Schultz