Synchronizable local clock for industrial controller system
US5661700A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 18, 1994 |
| Grant date | Aug 26, 1997 |
| Priority date | — |
| Expiry date | Jul 18, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04J3/067
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method of providing a standard coordinated time throughout spatially separated functional modules of an industrial controller employs a module operating as a time master which transmits a coordinated time to various dependent modules through communication modules. The dependent modules have local clocks which are synchronized to the coordinated time value by adjusting their clock frequency according to the difference between local time provided by that clock and the coordinated time value. This gradual correction prevents lost count values and disruption to the control process. The most and least significant bits of the time value may be transmitted at separate rates to reduce link traffic.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.