Donald Elwin Henry

US Patent:

42176581, Aug 12, 1980

Filed:

Jul 25, 1977

Appl. No.:

5/819038

Inventors:

Donald E. Henry - Bettendorf IA
Thomas A. Murrell - Urbana IL
Marvin H. Schilt - Bettendorf IA
Alfred C. Weaver - Champaign IL

Assignee:

Struthers-Dunn, Inc. - Pitman NJ

International Classification:

G06F 1546

US Classification:

364900

Abstract:

A process control system for controlling a set of outputs according to a multiplicity of inputs. The process control system analyzes the condition of the inputs as though they were arranged in a hypothetical ladder diagram which is a representation of the circuitry that would be required to control the loads if simple switches were interconnected, by wires, in the conventional way to control the loads. The hypothetical ladder diagram includes a plurality of hypothetical horizontal rows of circuit elements in which the circuit elements are also located in hypothetical vertical columns. All of the hypothetical vertical columns, except the last, are "input" vertical columns since they represent input circuit elements. The last vertical column contains the loads (or outputs) and is an "output" vertical column. The hypothetical input vertical column at the left end of the hypothetical ladder is first analyzed by the processing unit to determine whether there is a potential (binary 1), or no potential (binary 0), at the output of each circuit element of that hypothetical vertical column.