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. 02, 1995
Filed:
Mar. 30, 1992
Makoto Kogure, Katsuta, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A duplex field bus system in which a transmission is provided by first and second transmission lines. At least one of field device, an upper-rank apparatus and an external power supply is connected to both of the first and second transmission lines so that power supply and communication can be performed by using either one of or both of the transmission lines selectively. When failure is detected in the currently used one of the first and second transmission lines, not only is the failed transmission line switched over into the other one transmission line, but also information related to the occurrence of failure is transmitted to other devices before the communication is restarted. Accordingly, even in the case where fatal failure related to the transmission line occurs in the field bus system, communication can be continued by automatically switching the transmission line used by the devices.