• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The present invention discloses a method of how to extend an existing message distribution unit for event-driven messages (e.g., Ethernet messages) to also convey timed messages. According to the invention, the existing message distributor unit is preceded by a low-level switching unit which arranges the timed messages and ensures that no event-controlled message occupies the designated output port of the timed message at the scheduled time of the timed message.
    公开号:AT512528A4
    申请号:T577/2012
    申请日:2012-05-15
    公开日:2013-09-15
    发明作者:
    申请人:Fts Computertechnik Gmbh；
    IPC主号:
    专利说明:

    1 • ··· * * · Φ ····················································· • ♦ • f * ♦ * ·· **
    Method and apparatus for switching timed and event-driven messages
    Patents: [1] US 5694542 Kopetz, H. Time-triggered communication control unit and communication method. Granted December 2,1997.
    [7] US 7,839,868. Kopetz, H. Communication method and system for the transmission of time-driven and event-driven Ethernet messages. Granted November 23,2010.
    Patent Applications: [3] US 2007/0083622 Wang et al. Ethernet Switch and Service Processing Method thereof. Pub, Date April 12,2007
    Other: [4] Kopetz, H. Real-Time Systems, Design Principles for Distributed Embedded Applications. Springer Verlag. 2011th
    [5] SAE standard AS6802 from TT Ethernet. URL: http://standards.sae.org/as6802 [6] IEEE 802.3 Ethernet standard. URL: http: // www jeee802.Org/3/ [7] IEEE 1588 Standard for a Precision Clock Synchronization Protocol for Network
    Measurement and Control Systems. URL: http://www.ieeel588.com/
    Technical environment
    The present invention is in the field of computer technology. It describes an innovative method of how event-driven and timed messages can be conveyed in a distributed real-time system.
    Brief description of the invention
    In distributed real-time systems, the required time conditions between the sensor inputs of a technical process and the outputs to the actuators of the technical process can be maintained exactly if the communication between the computer nodes of the distributed real-time system is timed [1]. In the predominant non-time critical communication systems, e.g. in ethernet, the communication becomes appropriate
    Submission copy 15.5.2012 the event-driven approach. The present invention describes an innovative method, such as an existing event-driven one
    Message distribution unit can be expanded cost-effectively, to convey timed messages.
    According to the invention, it is assumed that a message distributor unit consists of two subsystems, a low-level switching unit (LLVME) having a global time, and a high-level switching unit (HLVME) which need not have access to a global time and event-driven messages can convey. The LLVME contains the communication ports via which the end systems (computer nodes) or further message distribution units are connected. An incoming message via a communication port of the LLVME is analyzed in the LLVME to determine if the message belongs to the class of the event-driven or the class of timed messages. An event-driven message is forwarded to the HLVME for mediation. The HLVME examines the message and, taking into account the current message traffic, decides at which time the message will be passed from the HLVME to the LLVME for output to the designated output port of the LLVME.
    A timed message is routed by the LLVME directly to the designated output port in accordance with the timed message schedule stored in the LLVME. To ensure that the designated output port is not occupied by an event-driven message at the a priori known transmission time of the timed message, the LLVME sends a pause frame to the HLVME in time so that the HLVME does not schedule the output port at the time the timed message is transmitted.
    The following are some other terms used in this patent. A message is time-triggered (TT) message if the transmission time of the periodic message is specified in an a priori known schedule. A message is event-triggered (ET) message if the message's transmission time is determined according to the best-effort [4, p. 175] principle. A pauseframe is a message sent from the LLVME to the HLVME to notify the HLVME that no further messages may be sent to the LLVME for mediation during the time interval specified in the pauseframe. The time interval between the LLVME sending the pause frame and the latest beginning of the puff is called the activation jitter. To ensure that the designated output port of the LLVME is free at the a priori known transmission time of a timed message, the interval between the transmission of the pause frames from the LLVME to the HLVME and the scheduled transmission time of the message must correspond to the activation jitter.
    Since the structure and function of the pause frame is specified in IEEE Standard 802.3 for Ethernet messages, the present invention enables existing IEEE standard Ethernet message distribution units to cost-effectively expand by adding an LLVME for transmitting timed messages without the existing one Ethernet message distribution unit to make changes. Because some of the existing message distribution units in an ASIC
    Submissions 15.52012 3 • * • * • # * »· · ♦ t · * · * • ♦ · ** ♦ ·« «··« «* * • ·« · * * ·· ·· »♦« ♦ ·· are implemented and changes in an ASIC cause a high cost, the invention of great economic importance.
    The subdivision of a message distribution unit into two hierarchically arranged subsystems, with the lower subsystem performing the immediate switch and the overlaid subsystem deciding in which order the messages should be switched, is already known in the art and is described, inter alia, in [3]. In an extensive analysis of the patent and technical literature available to us, we have not found any information that suggests the proposed approach to integrating time-controlled and event-driven messaging.
    Summary
    The present invention discloses a method of how to extend an existing message distribution unit for event-driven messages (e.g., Ethernet messages) to also convey timed messages. According to the invention, the existing message distributor unit is preceded by a low-level switching unit which clears the switching of the timed messages and ensures that no event-controlled message occupies the designated output port of the timed message at the scheduled time of the timed message.
    Brief description of the drawings
    The present invention will be explained in detail with reference to the following drawings. Fig. 1 shows the structural structure of the extended message distribution unit. Fig. 2 shows the timing of transmission of a pause frame.
    Description of a realization
    The following concrete example deals with one of the many possible implementations of the new procedure.
    Fig. 1 shows the message distribution unit with the Low Level Switching Unit (LLVME) 102 and the High Level Switching Unit (HLVME) 101. According to the invention, the LLVME 102 has access to the global time with known precision [4, p.56]. This global time can be established according to the IEEE standard 1588 or with another manufacturer-dependent synchronization method. On the bidirectional communication ports 110 of the LLVME 102, the messages to be relayed arrive and the switched messages are output. Immediately after the arrival of a message via one of the communication ports 110, the LLVME 102 decides whether the incoming message is an ET message or a TT message. This decision must be clear. It can build on different information. The simplest case is when the contents of a dedicated message field in the
    Submission copy 15.5.2012
    Header of the message, e.g. the Ethernet Type Field [2] indicates whether the message is a TT message or an ET message. However, it is also possible to make this decision as part of an analysis of the MAC addresses, the port addresses or the time of arrival of a message, or the contents of a dedicated message field (or a combination of the information listed). The TT Ethernet standard [5] provides methods for identifying a timed message. If the incoming message is an ET message, it will pass it on to the HLVME for processing via the powerful communication channel 120. The HLVME decides, taking into account the type of message and the traffic available, when that message will be delivered to the LLVME over the efficient communication channel 121 so that the LLVME can issue the message via the designated pört address 110. The HLVME can also perform monitor functions to collect traffic information, communication channel utilization and eventual errors.
    If the LLVME 102 classifies a message as timed, then the message is dumped directly from the LLVME to the designated communication port of the LLVME according to the schedule stored in the LLVME at the scheduled issue time. The schedule must be loaded into the LLVME before scheduling scheduled messages. To ensure that the schedule has been taken over unaltered by an authorized authority, the loading of a new schedule can be secured using cryptographic protocols. The storage of the schedule can be saved within the LLVME by error-detecting or error-correcting codes.
    To ensure that at the time of issuance of a timed message via the designated LLVME 102 communication port, no event-driven message occupies this designated communication port, the LLVME must request a pause from the HLVME in good time prior to sending a timed message via a pause frame. Such a pause frame has been standardized in IEEE Standard 802.3.
    Fig. 2 illustrates the timing of the transmission of the pause frame to ensure the timeliness of the break. On the abscissa 200 of Fig. 2, the progression of time is shown. According to the schedule stored in the LLVME, at the a priori known time 230, the sending of the timed message from the LLVME via the designated output port 110 should begin. At this time, the designated output port of the LLVME must be free to transmit the timed message. We refer to the sum of the transmission time of the pause frame from the LLVME to the HLVME plus the maximum processing time of the pause frame in the HLVME plus the duration of the longest ET message to be transmitted at the designated output port as the activation jitter of the pause frame. The timeliness of sending the pause frame from the LLVME to the HLVME is given when the interval between the pause frame end time 210 and the designated send time 230 of the timed message corresponds to the activation jitter.
    In the case of a timed schedule with a laxity, the case illustrated in FIG. 2 may occur that the timed message does not arrive at LLVME until time 220. Due to the information stored in the schedule of the LLVME and the duration of the activation jitter known to the LLVME, the
    Submission Copy 15.5.2012 LLVME request the pause at the end of parental leave 210 from the HLVME even before this arrival 220 of the time-controlled message at the LLVME.
    Alternatively, the game in the timed schedule can be extended so that only after the arrival of the message at the LLVME the pause frame must be sent. This has the advantage that if no time-controlled message arrives also no break must be requested.
    The duration of the pause contained in the pause frame must be chosen so that the longest to be transmitted timed message has been transmitted before the end of the break. According to the invention, the pause frame may correspond in structure and function to the IEEE Standard 802.3
    If timed messages are also to be included in the monitor functions, then the LLVME also sends the timed messages to the HLVME. After the HLVME has analyzed a timed message (to collect the desired monitor information), the HLVME discards the timed message.
    The described method for the integration of timed and event-driven messages can be implemented in the software on a CPU, as logic in an FPGA device or as an independent ASIC device.
    Submission copy 15.5.2012
    权利要求:
    Claims (10)
    [1]
    6 • • · · · · · · · · · · • • • • • • • • • • • • • • • * * * * * * * * * * * * * * * * * * * * * ♦ Claims 1. A method for distributing event-controlled and timed messages by means of a distribution unit comprising an LLVME (Low Level Switching Unit) and a HLVME (High Level Switching Unit) and where the communication ports to the other switching units or the end systems to the LLVME are characterized in that the LLVME has access to a global timebase and can distinguish between ET messages and TT messages and where the LLVME forwards an ET message arriving on one of its ports to the HLVME such that the HLVME the ET message can be analyzed and scheduled before it returns this ET message to the LLVME for output to the designated output ports of the LLVME, and where the LLVME is timely prior to the well-known output of a TT message sends a pause frame to the HLVME, so that the transmission of no ET message is scheduled by the HLVME during the transmission slot pre-known and scheduled for the TT message, and where the LLVME matches an incoming TT message handing over her known schedule directly to the output to the designated output ports.
    [2]
    2. The method according to claim 1, characterized in that the LLVME sends the pause frame to Pauseframesendezeitpunkt to the HLVME, wherein the Pauseframesendezeitpunkt calculated from the scheduled transmission time of the timed message minus the implementation-dependent a priori known activation jitter.
    [3]
    3. The method according to claim 1, characterized in that the duration of the requested by means of Pauseframes break is determined by the sum of Akttivierungsjitters plus the a priori known maximum transmission time of the timed message.
    [4]
    4. The method according to one or more of claims 1 to 3, characterized in that a copy of a timed message is forwarded by the LLVME for monitoring purposes to the HLVME.
    [5]
    5. The method according to one or more of claims 1 to 4, characterized in that the pause frame in structure and function complies with IEEE Standard 802.3.
    [6]
    6. The method according to one or more of claims 1 to 5, characterized in that the LLVME sends the pause frame to Pauseframesendezeitpunkt only to the HLVME when Pauseframesendezeitpunkt a corresponding TT frame has arrived in the LLVME.
    [7]
    7. The method according to one or more of claims 1 to 6, characterized in that the timed message relevant schedule is loaded by means of a kiyptographisch secured protocol in the LLVME. Submission copy 15.5.2012
    [8]
    8. The method according to one or more of claims 1 to 7, characterized in that one of the stored in the LLVME schedule is secured by error-detecting codes.
    [9]
    9. The method according to one or more of claims 1 to 8, characterized in that one of the stored in the LLVME schedule is backed up by error-correcting codes.
    [10]
    Apparatus for transmitting time-controlled and event-driven messages, characterized in that the apparatus carries out one or more of the method steps recited in claims 1 to 8. Submission copy 15.5.2012
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
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    WO2003107609A1|2002-06-13|2003-12-24|Fts Computertechnik Ges.M.B.H.|Communication method and system for transmitting timed and event-driven ethernet messages|
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    CN107257311B|2017-08-09|2020-06-30|西安微电子技术研究所|Time-triggered communication hybrid data transmission scheduling method based on virtual link|
    CN107332794B|2017-08-09|2020-07-17|西安微电子技术研究所|Dynamic time slot locking method for time-triggered communication|
    EP3467598B1|2017-10-04|2021-09-29|TTTech Computertechnik AG|Method and apparatus for the determination of the slot-duration in a time-triggered control system|
    CN110035022B|2019-04-22|2021-04-23|中国航空无线电电子研究所|AFDXswitching method and switch based on time-triggered architecture|
    JP2020188330A|2019-05-13|2020-11-19|日立オートモティブシステムズ株式会社|Vehicle control device and vehicle control system|
    法律状态:
    2018-11-15| PC| Change of the owner|Owner name: TTTECH COMPUTERTECHNIK AG, AT Effective date: 20180926 |
    优先权:
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    ATA577/2012A|AT512528B1|2012-05-15|2012-05-15|Method and apparatus for switching timed and event-driven messages|ATA577/2012A| AT512528B1|2012-05-15|2012-05-15|Method and apparatus for switching timed and event-driven messages|
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    US14/397,809| US20150120803A1|2012-05-15|2013-05-14|Method and Device for Relaying Time-Triggered and Event-Triggered Communications|
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