The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 25, 1988
Filed:
May. 20, 1987
Jonathan Engdahl, Saline, MI (US);
Lawrence Esker, Ann Arbor, MI (US);
Thomas J Bray, Saline, MI (US);
Jeffery A Hanneman, Saline, MI (US);
Allen-Bradley Company, Inc., Milwaukee, WI (US);
Abstract
A redundant local area network uses two cables over which duplicate information is transmitted in parallel in the form of identical message frames. Each receiver on the network includes a circuit which evaluates the signals from the two cables and selects one of the signals to be processed. This circuit determines the length of the message frames received on each cable for a given transmission and indicates which cable, if any, carried the longer frame. The signal from the cable that carried the longer frame is then selected as the output of the receiver. Additional circuitry is provided to prevent two short frames on one cable from being considered as one long frame. An apparatus is provided to look at the historical reliability of the signals on the cables so that if one cable has had a significantly better performance than the other, a single poor transmission on the one cable will not cause the historically poorer cable to be selected until such time as the poorer cable has redeemed itself.