# US 7,356,617 B2 · Periodic control synchronous system

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- Number: US 7,356,617 B2
- Document ID: US7356617B2
- Status: Granted
- Kind: B2
- Application number: 09/841,102
- Filed: 2001-04-25
- Published: 2002-05-30
- Granted: 2008-04-08
- Earliest claimed: 2000-11-27
- Assignees: Mitsubishi Denki Kabushiki Kaisha
- Inventors: Kenji Suzuki; Yuusuke Ushio; Shinichiro Chino; Satoru Nakai
- Web page: https://patentgrep.com/patent/US7356617B2

## CPC

- H04J 3/0664: {unidirectional timestamps}
- H04L 9/40: Network security protocols
- G05B 2219/25479: Synchronize controllers using messages, add transmission time afterwards
- H04L 69/28: Timers or timing mechanisms used in protocols
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G)

## Abstract

A controller controls a time stamp providing unit to provide a periodic transfer packet with a time stamp showing the synchronous timing of periodic control designated by the control period timer using the global time indicated by a global timer. Devices are corrected to synchronize operation period timers with the periodic control, by using the time difference between the synchronous timing time of periodic control indicated by the time stamp of the transmitted periodic transfer packet and the global time indicated by global timers, at periodic operation timing of the operation period timers.

## Claims

### Claim 1

A periodic control synchronizing system for synchronizing periodic control between a controller connected in a network and devices connected to said network, wherein
said controller includes a first global timer and each of said devices comprises a respective second global timer controlled by said controller through said network, each of said devices farther including
an operation period timer which generates a synchronizing time for synchronizing periodic control of said device; and
a timer synchronizing unit which
determines a first time difference between a global time, indicated by said second global timer of said device, at the synchronizing time, and a synchronizing time indicated by said first global timer, and
determines a timer correction value of said operation period timer, based on the first time difference, wherein said operation period timer is corrected by said timer synchronizing unit, based on the timer correction value, at the synchronizing time.

### Claim 2 (depends on 1)

The periodic control sychronizing system according to claim 1, wherein
said first global timer of said controller is a master global timer,
each of said second global timers of said devices is a slave global timer,
said controller comprises a transmitting unit which transmits the synchronizing time, using global time indicated by the master global timer, to said devices as a periodic transfer packet, and
each of said devices comprises a periodic control unit which performs periodic control using the synchronizing time of the periodic transfer packet transmitted by said transmitting unit and the global time indicated by said slave global timer.

### Claim 3 (depends on 1)

The periodic control synchronizing system according to claim 1, wherein said timer synchronizing unit includes a detecting unit which detects whether the first time difference is within an allowable range, corrects said operation period timer based on the timer correction value when the time difference is within an allowable range, and does not correct said operation period timer when the time difference is outside of the allowable range.

### Claim 4 (depends on 1)

The periodic control synchronizing system according to claim 1, wherein said controller further includes
a control period timer which control a control period of said controller; and
a timer synchronizing unit which
corrects said control period timer by determining a second time difference between the global time, indicated by said first global timer of said controller, and the synchronizing time indicated by said controller, at a timing indicated by said control period timer, and
determines a timer correction value of said control period timer based on the second time difference.

### Claim 5 (depends on 4)

The periodic control synchronizing system according to claim 4, wherein said timer synchronizing unit detects whether the first time difference is within a specified allowable range, corrects said control period timer based on the timer correction value when the first time difference is within an allowable range, and does not correct said control period timer when the first time difference is outside of the allowable range.

### Claim 6

A periodic control synchronizing system for synchronizing periodic control between a controller connected in a network and devices connected to said network, wherein
said controller includes
a first global timer;
a control period timer which generates a control period for periodic control of said controller;
a time stamp providing unit which provides a periodic transfer packet with a time stamp showing a synchronizing timing synchronizing time of the control period, indicated by said control period timer, using global time indicated by said first global timer; and
a transmitting unit which transmits the periodic transfer packet provided with the time stamp to said devices, and
each of said devices includes
a second global timer controlled through said network;
a periodic control unit which synchronizes operation period of said device with the control period using the synchronizing time of the periodic control, indicated by the time stamp of the periodic transfer packet transmitted by said transmitting unit, and global time indicated by said second global timer;
an operation period timer which generates a synchronizing time for synchronizing periodic control of said device; and
a comparing unit which
compares the synchronizing time of the periodic control, indicated by the time stamp of the periodic transfer packet transmitted by said transmitting unit, and the global time indicated by said second global timer,
determines a time difference between the synchronizing time of the periodic control, indicated by the time stamp, and the global time indicated by said second global timer, and
determines a timer correction value of said operation control period timer based on the time difference, wherein said operation period timer is corrected by said comparing unit, based on the timer correction value, at the synchronizing time.

### Claim 7 (depends on 6)

The periodic control synchronizing system according to claim 6, wherein
said controller comprises a latch unit which latches the global time of said first global timer, and holds the time latched,
said control period timer latches the global time of said first global timer in said latch unit at the synchronizing time of the periodic control indicated by said control period timer, and
said time stamp providing unit provides the periodic transfer packet with the time stamp having the global time latched by said latch unit, offset by a portion of the control period.

### Claim 8 (depends on 6)

The periodic control synchronizing system according to claim 6, wherein said comparing unit, which detects whether the time difference is within an allowable range, corrects said operation period timer, based on the timer correction value, when the time difference is within the allowable range, and does not correct said operation period timer when the time difference is outside of the allowable range.

### Claim 9 (depends on 6)

The periodic control synchronizing system according to claim 6, wherein said comparing unit resets said operation period timer when the global time, indicated by said second global timer, reaches the synchronizing time of the periodic control indicated by the time stamp.

### Claim 10 (depends on 9)

The periodic control synchronizing system according to claim 9, wherein said comparing unit resets said operation period timer when reaching the synchronizing time, indicated by said operation period timer, before the global time, indicated by said second global timer, reaches the synchronizing time of the periodic control, indicated by the time stamp, and resets said operation period timer again, later, when the synchronizing time of the periodic control, indicated by the time stamp, at least reaches the global time indicated by said second global timer.

### Claim 11 (depends on 9)

The periodic control synchronizing system according to claim 9, wherein said comparing unit, which detects whether the time difference between the synchronizing time of the periodic control, indicated by the time stamp, compared by said comparing unit, and the global time, indicated by said second global timer, at the synchronizing time, indicated by said operation period timer, is within an allowable range, and does not correct said operation period timer when the time difference is outside of the allowable range.

### Claim 12 (depends on 9)

The periodic control synchronizing system according to claim 9, wherein said comparing unit determines a timer period correction value of said operation period timer from the time difference between the synchronizing time of the periodic control, indicated by the time stamp, and the global time, indicated by said second global timer, and thereby corrects said operation period timer based on the timer period correction value.