Timer synchronizing device and initializing method for use in ring communication path

• US 6,185,217 B1
• Filed: 02/17/1998
• Issued: 02/06/2001
• Est. Priority Date: 12/02/1996
• Status: Expired due to Term

• Current Assignee: Okuma Corporation
• Original Assignee: Okuma Corporation
• Inventors: Eba, Koji, Ando, Toru
• Primary Examiner(s): Kizou, Hassan
• Assistant Examiner(s): Tsegaye, Saba
• Application Number:
  US09/025,076
• Time in Patent Office: 1,085 Days
• Field of Search: 370/503, 370/509, 370/510, 370/512, 370/258, 370/222, 370/252, 370/403, 370/452, 370/460, 342/384, 342/397, 375/355, 375/356, 375/357, 455/502, 709/208, 709/251
• US Class Current: 370/403
• CPC Class Codes: H04J 3/0655 using timestamps
• CPC Class Codes: H04J 3/0682 by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging
• CPC Class Codes: H04L 12/422 Synchronisation for ring networks Time Division Multiplex ring networks, e.g. SDH/SONET H04J3/085
• CPC Class Codes: H04L 12/423 with centralised control, e.g. polling

Abstract

A device and an initializing method for use in a ring communication path, which can highly accurately synchronize time of the master and slave stations so as to achieve accurate communication among those stations. According to this device and method in which timers of respective slave stations connected to a ring communication path are synchronized using a specific communication frame, a master station recognizes the number of slave stations and their connection sequences, and notifies each of the slave stations of an individual communication delay time. Respective slave stations correct their timers so as to agree to that of the master station.

Claims

1. A timer synchronizing device for synchronizing timers of respective slave stations connected to a ring communication path by using a specific communication frame, comprising;

a notifier installed in a master station for notifying each slave station of a transmission delay time according to a transmission delay time provided to the master station by a previous slave station;

a corrector installed in each slave station for correcting a time difference for synchronization between a timer of the master station and a timer of the slave station; and

a recognizer installed in a master station for recognizing the number of slave stations connected to the ring communication path, and their respective connection sequences.

2. An initializing method for initializing communication addresses of slave stations connected to a ring communication path for synchronization of timers of the slave stations by using a specific communication frame, comprising:

a step in which the master station notifies each slave station of a transmission delay time according to a transmission delay time provided to the master station by a previous slave station; and

a step in which each slave station corrects a time difference caused in synchronization between a timer of the master station and a timer of the slave station; and

a step in which a master station recognizes the number of the slave stations connected to the ring communication path and connection sequences thereof.

3. The method as defined in claim 2, further comprising:

a step in which the master station calculates the transmission delay times to notify the slave stations, based on an accumulated value of respective transmission delay times, of which the slave stations individually inform the master station at initialization.