Abstract: An operator station for a manufacturing process control system including a network of at least one dedicated process control computer for monitoring and controlling SECTIONS of the manufacturing process wherein each SECTION includes one or more SEQUENCES of the manufacturing process, the operator station includes a processor, a communication link to the process control communication system, a display including a SECTIONS window providing information relating to at least one of the SECTIONS monitored by the operating station and a SEQUENCE window providing information relating to one or more SEQUENCES monitored by the operator station, a data input device for selecting a SECTION from which information is to be displayed. The operator station may further include a flow sheet display window which includes a graphic depiction of a portion of the process, and a trend display window which includes current and historical information in graphic form for selected process control variables.

Abstract: 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.

Abstract: 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.