The Dow Chemical Company

Dow Global Technolgoies LLC

Eloy Baca, Jr

Johannes C Kanse

Wayne P Dupree

Edward R Sederlund

Robert J Lindesmith

Oscar E Schulze

Donald J Grinwis

Augustine Tibazarwa

John L Clement

Helmut A Bezecny

Ernst W Quelle

Donald Grinwis

Dennis J Dunlap

Brent M Frank

Douglas P Pelletier

A process control system receiving input signals from a controlled apparatus and using the input signals in determining at least one output signal modifying the characteristics of at least one respective control device in the controlled apparatus where the source code for the general control of the apparatus and the source code for the safety shutdown system of the apparatus are compiled to control code in a unified compilation.

Process control system with integrated safety control system

A method of input signal resolution in a process control system where each of the actively redundant process control computers performs a common arbitration process on corresponding input signals. Blocks of corresponding input signals are mutually exchanged by the actively redundant process control computers, and an initial check is made to determine if these input signals are valid. For input signals representing valid analog values, a determination is made as to whether a predefined tolerance has been exceeded between corresponding input signals in the present process control cycle. When the predefined tolerance has been exceeded, then a check will be made to determine the predefined tolerance was also exceeded in the last process control cycle. If the predefined tolerance was not exceeded in the last process control cycle, then the analog input value selected during the last process control cycle will be employed in the present process control cycle. If the predefined tolerance was exceeded in both the present and the last process control cycle, then a predetermined magnitude criteria will be used to select the analog input value for use in making process control decisions. An indication will also be provided in each of the actively redundant process control computers to identify which of the corresponding input signals were selected by that process control computer.

Method of input signal resolution for actively redundant process control

Growing community of inventors

Attleboro, MA, United States of America

Eloy Baca, Jr