US 2013/0170388 A1Published application

Communication apparatus and delay detecting method

AssigneeMitsubishi Electric Corporation

InventorsTeruaki Ito, Tomoyuki Fujita, Yasuto Kanayama

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Abstract

A communication apparatus includes a time-stamp generating unit for generating a time stamp during transmission or reception of a PDU transmitted and received, a transmission-data storing unit, a reception-data storing unit, a frame processing unit configured to generate a PDU including a data refresh instruction to the other node, periodical transmission data in the transmission-data storing unit, and a frame transmission time acquired from the time-stamp generating unit and store, upon receiving a PDU from the other node, periodical transmission data included in the PDU in the reception-data storing unit, and a one-way-delay detecting unit for determining, upon receiving the PDU, according to whether a next PDU has been received within a first delay allowable time after the last PDU was received, or whether a transmission time of the PDU is within a second delay allowable time, presence or absence of occurrence of a delay of a PDU.

Claims23

Dependent claims

A communication apparatus that performs periodical communication with another communication apparatus connected via a transmission line, the communication apparatus comprising:

a clock configured to measure time;
a communicating unit configured to transmit and receive a communication frame;
a time-stamp generating unit configured to generate a time stamp using the clock during transmission or during reception of the communication frame transmitted and received by the own communication apparatus;
a transmission-data storing unit configured to store periodical transmission data stored in the periodically-transmitted communication frame;
a reception-data storing unit configured to store the periodical transmission data in the periodically-received communication frame;
a frame processing unit configured to generate a refresh instruction frame including a data refresh instruction to the other communication apparatus, the periodical transmission data in the transmission-data storing unit, and a frame transmission time, which is a time stamp of transmission timing, acquired from the time-stamp generating unit and store, upon receiving a refresh instruction frame from the other communication apparatus, periodical transmission data included in the refresh instruction frame in the reception-data storing unit;
and
a one-way-delay detecting unit configured to determine, upon receiving the refresh instruction frame, whether a next refresh instruction frame is received within a first delay allowable time after the refresh instruction frame is received last time and determine, when the next refresh instruction frame is received within the first delay allowable time, according to whether a transmission time of the refresh instruction frame from the other communication apparatus to the own apparatus is within a second delay allowable time, whether a delay has occurred in a communication frame transmitted from the other communication apparatus.

5 more elements

A delay detecting method by any one of two communication apparatuses connected via a transmission line in a communication system in which periodical communication is performed between the two communication apparatuses, the delay detecting method comprising:

a first timer starting step of starting a timer when the periodical communication is started;
a first one-way-delay determining step of determining whether a refresh instruction frame including a refresh instruction from another communication apparatus is received within a predetermined time from the start of the timer;
a frame-reception-time acquiring step of acquiring, when the refresh instruction frame is received at the first determining step, a frame reception time of reception timing of the refresh instruction frame;
a frame-transmission-time acquiring step of acquiring a frame transmission time, which is a transmission time of the refresh instruction frame by the other communication apparatus stored in the refresh instruction response frame;
a second one-way-delay determining step of determining presence or absence of delay occurrence using the frame reception time and the frame transmission time;
and
a timer restarting step of restarting the timer after the second one-way-delay determining step.

4 more elements

Dependencies are inferred from the claim text.