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:
May. 17, 1994
Filed:
Jun. 11, 1992
William B Cook, Northfield, OH (US);
Robert D Eaton, North Ridgeville, OH (US);
Allen-Bradley Company, Inc., Milwaukee, WI (US);
Abstract
A machine is controlled by a system which has a pair of programmable controllers connected in tandem. One controller operates in the active mode governing the operation of the machine, while the other controller is in a backup mode able to assume control of the machine should the active controller fail. Each programmable controller has a backup module through which the two controllers are connected. In order to determine which controller is to be active upon power up, each backup module has an input means for receiving a first active mode request signal from another programmable controller. A means is provided to produce a tie breaker signal at one backup module which indicates that its programmable controller is to operate in the active mode when both programmable controllers simultaneously desire to operate in the active mode. A mode indicator in the backup module designates the active mode when the input means does not receive the first active mode request signal, or when the input means is receiving the first active mode request signal and the tie breaker signal is being produced at that backup module. Otherwise, the mode indicator designates that the programmable controller is to operate in the backup mode. An output means transmits a second active mode request signal to the other programmable controller when the mode indicator designates the active mode.