# US 9,823,641 B2 · PLC communication system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,823,641 B2 - Document ID: US9823641B2 - Status: Granted - Kind: B2 - Application number: 14/243,159 - Filed: 2014-04-02 - Published: 2014-11-13 - Granted: 2017-11-21 - Earliest claimed: 2013-05-07 - Assignees: Jtekt Corporation; Toyota Jidosha Kabushiki Kaisha - Applicants: JTEKT Corporation; Toyota Jidosha Kabushiki Kaisha - Inventors: Terukazu Senda; Satoshi Kato; Toshio Aono; Toshiyuki Kamauchi; Masanori Ido - Web page: https://patentgrep.com/patent/US9823641B2 ## CPC - G05B 19/058: {Safety, monitoring} - G05B 19/4185: {characterised by the network communication} - H04L 12/403: with centralised control, e.g. polling - H04L 41/0677: Localisation of faults - H04L 43/0811: by checking connectivity - H04L 43/10: Active monitoring, e.g. heartbeat, ping or trace-route - G05B 2219/15026: Detection of data transmission faults - H04L 43/16: Threshold monitoring - H04L 2012/445: {with switching in a hub, e.g. ETHERNET switch} - Y02P 90/02: Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS] - 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) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract The PLC communication system associated with the invention is characterized in that the system comprises a programmable logic controller (PLC), a plurality of processing devices, at least three communication processing nodes provided at the PLC and at the plurality of processing devices respectively to establish communication of the PLC and each of the processing devices and an interconnecting device and a plurality of communication lines for connecting the communication processing nodes with one another to establish data communication among the communication processing nodes. The PLC detects a state of communication failure and a display device displays an abnormal portion in a communication route based on the number of occurrences of the state of communication failure in respective interconnecting device and plurality of communication lines. ## Claims ### Claim 1 A PLC communication system comprising: a programmable logic controller (PLC); a plurality of processing devices; at least three communication processing nodes provided at the PLC and the plurality of processing devices respectively to establish communication among the PLC and the plurality of processing devices; and an interconnecting device and a plurality of communication lines for connecting the communication processing nodes to form a communication route among the communication processing nodes, wherein the PLC detects a communication failure state in the communication route formed by the communication processing nodes when a first communication processing node reissues data to a third communication processing node after failing to receive expected data from a second communication processing node, a content of the reissued data including a content of the expected data, and a display device displays an abnormal portion in the communication route based on a number of occurrences of the detected communication failure state in the interconnecting device and the plurality of communication lines. ### Claim 2 (depends on 1) The PLC communication system according to claim 1, wherein the display device displays the abnormal portion in the communication route, excluding a portion forming a normal communication route from among the communication routes which are judged to be in the communication failure state in the interconnecting device and the plurality of communication lines. ### Claim 3 (depends on 1) The PLC communication system according to claim 1, wherein the display device displays a communication circuit including all of the communication routes and the abnormal portion in the communication routes by differentiating the abnormal portion from other portions. ### Claim 4 (depends on 1) The PLC communication system according to claim 1, wherein the display device displays a portion in which the number of occurrences of the detected communication failure state is equal to or more than a first threshold value as the abnormal portion and a portion in which the number of occurrences of the detected communication failure state is less than the first threshold value and equal to or more than a second threshold value as a warning portion, and the display device displays the warning portion by differentiating the warning portion from the abnormal portion and other portions. ### Claim 5 (depends on 1) The PLC communication system according to claim 1, wherein the display device displays the number of occurrences of the communication failure state in the interconnecting device and the plurality of communication lines, respectively. ### Claim 6 (depends on 1) The PLC communication system according to claim 1, wherein an FL-net (FA LINK network) is used for the communication lines, each of the communication processing nodes receives and sends a token from one communication processing node after another, when the token is not received at the first communication processing node from second communication processing node, a retrial processing is executed, where a re-issued token, generated locally, is sent from the first communication processing node to the third communication processing node, and the PLC recognizes the communication route connecting the second and the first communication processing nodes to be the communication route which is in the communication failure state, after the retrial processing was executed with a predetermined number of times. ### Claim 7 (depends on 6) The PLC communication system according to claim 6, wherein the display device further displays a number of times of retrial processing in the each of the communication processing nodes. ### Claim 8 (depends on 1) The PLC communication system according to claim 1, wherein the PLC detects the communication failure state in the communication route formed by the communication processing nodes when the first communication processing node reissues data to the third communication processing node after failing to receive expected data from the second communication processing node within a predetermined time period. ### Claim 9 (depends on 1) The PLC communication system according to claim 1, wherein the reissued data and the expected data are both a data transmission privilege.