Abstract: A logic controller includes a memory for storing representations of boolean logic. The boolean logic includes AND and OR boolean logic functions having target values and a plurality of inputs. The processor of the logic controller has input/output circuitry and communications circuitry which provide a plurality of input/output digital logic signals. The processor employs the digital logic signals and solves the boolean logic representations. A firmware routine solves each boolean logic function when the value of any of its inputs is equal to its target value.

Abstract: A modular input/output (I/O) system for field wiring includes a plurality of base units into which electronics modules providing appropriate signal processing are plugged. A backplane in each base unit provides leads between the electronics module and associated terminals to which the field wiring is connected and also hosts a communications bus through which the electronics modules on serially connected base members communicate with a controller. Switching modules plugged into some of the base members selectively switch field signals applied to terminals for an associated electronics module to another electronics module for redundancy, or switch test signals into the associated electronics module in place of the field wiring signals. The test signals are generated by yet another of the electronics modules while still another electronics module generates control signals for the switching modules.

Abstract: A distributed process control system drop for controlling the operation of an industrial process includes a first workstation or personal computer running industrial continuous process control software on an open architecture operating system and operable to analyze input information provided from the industrial process according to a predetermined set of rules and generate output information provided to the industrial process to control the operation thereof. A second workstation or personal computer connected with the first workstation via a non vendor-specific, international standards-based data highway normally runs in a backup mode and also runs the industrial process control software on an open architecture operating system to perform the same analysis as the first workstation and generate backup output information.

Abstract: A modular input/output (I/O) unit utilizes plug-in personality modules to provide any one of a variety of interfaces between I/O signal processing cards mounted in plug-in electronics module and a bank of terminals providing connections for field wiring.