Patent ID: 9270554
Filing Date: 2016-02-23
CPC Classification: H04J,H04L

Claim Text:
1. A communication apparatus that performs periodical communication with other 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 communication apparatus; a transmission-data storing unit configured to store periodical transmission data to be transmitted in periodically-transmitted communication frame; a reception-data storing unit configured to store periodical reception data received in periodically-received communication frame; a frame processing unit configured to generate a refresh instruction frame, of the communication frame, including a data refresh instruction to the other communication apparatus, the periodical transmission data from the transmission-data storing unit, and a frame transmission time, which is the time stamp of transmission timing acquired from the time-stamp generating unit, and to store, upon receiving a refresh instruction frame from the other communication apparatus, the periodical reception data included in the refresh instruction frame into 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 to 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 communication apparatus is within a second delay allowable time, whether a delay has occurred in a communication frame transmitted from the other communication apparatus, wherein the one-way-delay detecting unit uses, as the transmission time, a difference between a frame reception time acquired from the time-stamp generating unit at the reception time of the refresh instruction frame and the frame transmission time stored in the refresh instruction frame.