DE102008004854B4 - Method for transmitting messages in a bus system, bus device and bus system - Google Patents

Method for transmitting messages in a bus system, bus device and bus system

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Publication number
DE102008004854B4
DE102008004854B4 DE102008004854.2A DE102008004854A DE102008004854B4 DE 102008004854 B4 DE102008004854 B4 DE 102008004854B4 DE 102008004854 A DE102008004854 A DE 102008004854A DE 102008004854 B4 DE102008004854 B4 DE 102008004854B4
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Germany
Prior art keywords
bus
device
transmission signals
processed
signals
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DE102008004854.2A
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German (de)
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DE102008004854A1 (en
Inventor
Paul Milbredt
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Audi AG
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Audi AG
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Priority to DE102008004854.2A priority Critical patent/DE102008004854B4/en
Publication of DE102008004854A1 publication Critical patent/DE102008004854A1/en
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00Data switching networks
    • H04L12/28Data switching networks characterised by path configuration, e.g. local area networks [LAN], wide area networks [WAN]
    • H04L12/46Interconnection of networks
    • H04L12/4604LAN interconnection over a backbone network, e.g. Internet, Frame Relay
    • H04L12/462LAN interconnection over a bridge based backbone
    • H04L12/4625Single bridge functionality, e.g. connection of two networks over a single bridge
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00Data switching networks
    • H04L12/28Data switching networks characterised by path configuration, e.g. local area networks [LAN], wide area networks [WAN]
    • H04L12/40Bus networks
    • H04L12/407Bus networks with decentralised control
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00Data switching networks
    • H04L12/28Data switching networks characterised by path configuration, e.g. local area networks [LAN], wide area networks [WAN]
    • H04L12/40Bus networks
    • H04L2012/40208Bus networks characterized by the use of a particular bus standard
    • H04L2012/40241Flexray
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00Data switching networks
    • H04L12/28Data switching networks characterised by path configuration, e.g. local area networks [LAN], wide area networks [WAN]
    • H04L12/40Bus networks
    • H04L2012/40267Bus for use in transportation systems
    • H04L2012/40273Bus for use in transportation systems the transportation system being a vehicle

Abstract

Method for transmitting messages from a transmitting device (10) to a receiving device (12) via a processing device (14) in which the messages are processed, a sequence of time slots (22) being defined in a communication system, and transmitting signals (26, 26 ') are transmitted from the transmitting device (10) in predetermined time slots (22) from this sequence, wherein the processing device (14) transmits from it received and processed transmission signals at least partially in the same time slot (22) in which it has received them characterized in that the processing device (14) detects how exactly a clock associated with it is synchronized with a clock of the transmitter (10), and estimates or calculates how long it takes to receive and process until the transmission of the transmission signals, and that it derives from these two pieces of information whether a minimum remaining buffer time (28 ') remains in the time slot (22) from a buffer time (28) and in this case, retransmit the transmission signals it has processed in the same time slot in which it received them.

Description

  • The invention relates to the field of time-triggered communication systems, namely those in which the time is divided into a plurality of time slots. The individual subscribers of the communication system are assigned to certain of these time slots, so that said subscribers can then deliver in the time slots assigned to them transmit signals. Usually, the time slots are assigned to the individual subscribers in a cyclical sequence. The communication method requires that the individual subscribers, also referred to as "nodes", must synchronize. Known protocols for data transmission in such communication systems are FlexRay, TTP / C and TTCAN.
  • From the US 2006/0248249 A1 Systems and methods are known for multi-input meter buses. The bus assembly includes a control module configured to be coupled to a network and a plurality of nodes operatively coupled in a linear topology. A plurality of interface modules are coupled to the nodes. At least one node is configured to receive a primary response signal from the correspondingly coupled interface module and a secondary response signal from at least one other node, and determine which of the primary and secondary signals arrived first, and a corresponding signal of the primary and the secondary secondary response signal, which arrived first to spend.
  • In particular, the invention is concerned with the transmission of messages which are transmitted by a transmitting device and processed in a processing device before they reach a receiving device.
  • If one wants to process signals from another bus subscriber in a bus subscriber, this necessitates a separation of a bus into two branches in the prior art. For example, when using the FlexRay protocol, at least two nodes (bus users) are required for synchronization within a branch. So is lost when disconnecting the bus synchronization. Namely, the bus subscribers from one of the branches receive only signals via the bus subscribers handling these signals and separating the branches from each other. In order not to violate the protocol, for each branch the remaining bus must be simulated, and in such a simulation the time bases drift apart. In the prior art, the processing bus device (the processing device) receives the signals from the transmitting device in a first timeslot and retransmits them in the corresponding timeslot of the other branch after processing. This second time slot must be a time slot associated with the transmitter. It is usually the next time slot in the sequence of time slots associated with the predetermined time slots defined for the transmitter.
  • Because of the separation of a bus into two branches by editing the communication system must be very complex overall. Because of the transmission of the signals in the respective next time slot belonging to the transmitter, the messages from the transmitter arrive, even with considerable delay, firstly at the receiver, which in the worst case is as large as the cycle time of the time slots.
  • It is an object of the invention to eliminate these disadvantages of the prior art.
  • The object is achieved by a method having the features according to claim 1 and a method enabling this bus device having the features according to claim 3. By the method according to the invention or when using the bus device according to the invention, a bus system with the features according to claim 4 is also possible.
  • In the method according to the invention, the processing device thus at least partially (in particular if possible according to predetermined criteria) transmits transmitted signals received and processed by it again in the same time slot (with delay, of course) in which it received them.
  • The invention consists in using a buffer time usually defined in the timeslot. The length of a time slot is usually greater than the length of a message (a so-called frame). The transmission of the message is started only after a buffer time has elapsed, and a buffer time remains after the transmission of the frame in the time slot has ended. The buffer times are defined because the individual devices are not perfectly synchronized with each other. Usually, however, the buffer times are very generous. Therefore, it is provided that the processing device (in advance, ie before receiving the transmission signals) detects how exactly a corresponding clock (timer) is synchronized with a clock (a timer) of the transmitting device. In addition, it must (in advance in particular) estimate or calculate how long the processing of the transmission signals takes. Because of the first information, the processing device determines how much of the buffering time is actually required due to the imperfect synchronization of the two clocks is (minimum remainder buffer time). Based on the second information, the time delay with which the processing device sends out the processed transmission signals is estimated. It is estimated by how much the buffer time is shortened. Thus it is deduced whether the minimum remaining buffer time remains from a buffer time in the time slot. For this purpose, a residual buffer time of greater than a certain microsecond number can be specified, but the minimum residual buffer time can also be equal to 0 microseconds if perfect synchronization has been assumed. If the minimum remaining buffer time remains, then the transmitted transmission signals are transmitted in the same time slot in which they were received.
  • Due to the time delay of sending the processed transmission signals through the processing unit, errors in the synchronization could occur. This would be the case in particular if the transmission signals comprise a synchronization signal which is transmitted unchanged with time delay. Therefore, the processing apparatus should disable (cancel) a sync signal included in the transmit signal, for example, reset (to 0) a sync bit set to (1).
  • The bus device according to the invention is designed to retransmit processed transmission signals in the same time slot with delay, in which it receives them. It is furthermore designed to determine a remaining buffer time remaining from a buffer time after receiving and processing until retransmission of the transmission signals, and to retransmit the processed transmission signals in the same time slot with delay only when the residual buffer time has reached a minimum value exceeds. Should the remaining buffer time not be sufficiently large, the prior art method will be followed, meaning that the transmit signals will be forwarded in the next time slot allocated to the transmitter from which they originate.
  • The invention includes the first-time provision of a bus system, which may be configured in particular as a FlexRay bus system, wherein a plurality of bus devices belonging to the bus system, a transmitting device emits the transmission signals, which are processed by a processing device, which is a bus device of the type according to the invention before being sent to a receiving device, unlike the prior art, all bus devices are connected to the same one (FlexRay) bus and therefore can also be synchronized.
  • It thus eliminates the effort required by the division of the bus into two branches in the prior art. Due to the synchronizability of all bus devices a good functioning of the communication in the bus system, in particular without time delay is guaranteed.
  • Hereinafter, a preferred embodiment of the invention will be described with reference to the drawings, wherein
  • 1 illustrates a communication system according to the prior art,
  • 2 illustrates a communication system according to the invention, which is designed as a coherent bus system,
  • 3A the time course of the transmission of signals in a time slot by a transmitting device and
  • 3B the time course of the transmission of signals by a processing device, the in 3A has received and processed signals illustrated using the method according to the invention.
  • A transmitter 10 sends in a timed communication system transmission signals in predetermined, namely exactly the transmitter 10 assigned time slots, see 1 , Before the transmission signals to a residual bus 12 , in particular to a receiving device, they should pass through a processing device 14 to be edited. The processing device 14 usually operates to receive and process the transmission signals in one time slot and then in the next to the transmission equipment 10 forwarded allocated time slot. This results in a delay in the transmission of the transmission signals, which corresponds to the time interval between two time slots that belong to the same device, that is defined by the so-called transmission frequency. The procedure in the prior art requires that the communication system by the processing unit 14 divided into two parts, namely a first FlexRay cluster 16 and a second FlexRay cluster 18 , The two FlexRay clusters are each branches of a FlexRay bus. The two FlexRay clusters no longer have a common time base. Rather, the first FlexRay cluster has 16 a first time base and the second FlexRay cluster 18 a second time base, transmitter 10 on the one hand and residual bus 12 on the other hand, with the receiving device are no longer synchronized.
  • The inventive method now allows - see 2 - Providing a bus system 20 , at the transmitter 10 , Processing device 14 and rest bus 12 are connected to the receiver on a single FlexRay bus, so there is only one FlexRay cluster, whereby all bus users (bus devices) receive a common time base.
  • The inventive method, which of the processing device 14 will now be explained with reference to a temporal waveform. 3A shows the waveform in a whole with 22 designated time slot. The time slot 22 is in a first section 24 , a second section 26 and a third section 28 divided. The sections 24 and 28 are buffers. In the section 26 the actual message or message is sent, that is a so-called frame. A frame has a predetermined length, and this is shorter than a time slot. For example, the duration of a frame is 65 μs. The buffer 1 (section 24 ) has a duration of 5 μs, and buffer 2 (section 28 ) has a duration of 7 μs. Overall, the timeslot has 22 ie a duration of 77 μs with a duration of a frame of 65 μs. Exemplary is in 3A a signal 30 shown in the frame 26 is transmitted. The processing device 14 now receives more or less in the 3A Ideal signal shown: Sends the transmitter 10 the frame 26 in the time slot 22 just like in 3A shown receives the processing device 14 the signals also correspond when the clock of the processing unit 14 Perfect with the transmitter 10 is synchronized. The processing device 14 As part of a continuous data flow, it can now determine how well its clock is synchronized with that of the transmitter. The error in the synchronization causes the minimum remainder buffer time remaining in the time slot 22 after completion of sending the frame 26 may still remain. The processing device 14 It takes a certain amount of time to receive and edit until the retransmission can begin. This also takes into account the processing unit 14 , The processing device 14 can detect whether a minimum remainder buffer time from buffer 2 (section 28 ), in view of the synchronization error between the clock of the processing device 14 and the clock of the transmitter 10 has been defined, given the time required to receive, edit, and retransmit. If so, send the processing device 14 for example in a time slot 22 the frame 26 ' as in 3B shown with a predetermined delay 32 , The duration of the section 28 will be the same delay 32 shortened, leaving a shorter section 28 ' results. The processing device 14 here has determined that the duration of the section 28 ' is sufficiently large to account for the synchronization error.
  • The invention makes use of the use of the buffers, in particular that there is the buffer 2, that is a buffer, after the completion of a frame 26 is provided. Because of the presence of this buffer 2, it is possible to frame the frame after its processing 26 ' with delay 32 (if the delay 32 not too big).
  • It can if the editing device 14 only the signal 30 edited, already with the retransmission with the delay 32 be started before the frame 26 was completely received, so too, before the signal 30 was received. The reception time when calculating the delay 32 is set, is only for the pure electronic process of receiving in the processing unit 14 necessary time and does not include a wait from the beginning of the frame 26 up to the signal to be processed 30 ,

Claims (4)

  1. Method for transmitting messages from a transmitting device ( 10 ) via a processing device ( 14 ), in which the messages are processed, to a receiving device ( 12 ), wherein in a communication system a sequence of time slots ( 22 ) and transmit signals ( 26 . 26 ' ) from the transmitter ( 10 ) in predetermined time slots ( 22 ) are transmitted from this sequence, wherein the processing device ( 14 ) received and processed by him transmit signals at least partially in the same time slot ( 22 ), in which it has received it, characterized in that the processing device ( 14 ), how exactly a belonging to him clock with a clock of the transmitter ( 10 ), and that it estimates or calculates how long it takes to receive and process until the transmission of the transmitted signals, and that it derives from these two pieces of information whether a buffer time ( 28 ) in the timeslot ( 22 ) a minimum remainder buffer time ( 28 ' ) remains and in this case sends out the transmission signals which it has processed in the same time slot in which it received them.
  2. Method according to Claim 1, in which the processing device ( 14 ) suppresses a synchronization signal contained in the transmission signals.
  3. Bus device ( 14 ) for receiving and processing transmission signals from another bus device ( 10 ) when connecting both bus devices ( 10 . 14 ) is designed for a bus in which a sequence of time slots is defined and the transmission signals from the other bus device ( 10 ) are transmitted in predetermined time slots, wherein the bus device ( 14 ) is adapted to process processed transmission signals in the same time slot ( 22 ) with delay ( 32 ), in that it receives it, characterized in that it is adapted to a residual buffer time remaining from a buffer time after receiving and processing and retransmitting transmission signals ( 28 ' ) and the processed ones Transmit signals only in the same timeslot ( 22 ) with delay, in which it has received it, if the remaining buffer time ( 28 ' ) exceeds a minimum value.
  4. Bus system ( 20 ) with a plurality of bus devices ( 10 . 12 . 14 ), wherein a processing device ( 14 ) the bus device is a bus device according to claim 3 and for processing by a transmitting device ( 10 ) of the bus devices emitted transmission signals is designed before the processed transmission signals to a receiving device ( 12 ) of the bus devices, all bus devices ( 10 . 12 . 14 ) are connected to the same bus and synchronized.
DE102008004854.2A 2008-01-17 2008-01-17 Method for transmitting messages in a bus system, bus device and bus system Active DE102008004854B4 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE102008004854.2A DE102008004854B4 (en) 2008-01-17 2008-01-17 Method for transmitting messages in a bus system, bus device and bus system

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE102008004854.2A DE102008004854B4 (en) 2008-01-17 2008-01-17 Method for transmitting messages in a bus system, bus device and bus system
PCT/EP2008/010072 WO2009089869A1 (en) 2008-01-17 2008-11-27 Method for transmitting messages in a bus system, bus device and bus system
AT94002008A AT512449B1 (en) 2008-01-17 2008-11-27 Method for transmitting messages in a bus system, bus device and bus system

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DE102008004854A1 DE102008004854A1 (en) 2009-07-23
DE102008004854B4 true DE102008004854B4 (en) 2015-06-18

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Citations (4)

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US20060143345A1 (en) * 2002-12-17 2006-06-29 Kvaser Consultant Ab Schematizing of messages in distributed control and supervision system
US20060248249A1 (en) * 2005-04-29 2006-11-02 The Boeing Company Systems and methods for multiple input instrumentation buses
DE102004063213B4 (en) * 2004-12-24 2006-11-23 Pilz Gmbh & Co. Kg Control system with a plurality of spatially distributed stations and method for transmitting data in such a control system
DE102005060085A1 (en) * 2005-12-15 2007-06-21 Beckhoff Automation Gmbh Data transmitting method for e.g. Ethernet-network, involves subdividing sending cycle into sub cycles using control unit so that data in form of telegram is communicated between nodes connected to transmission line in each sub cycle

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10327548B4 (en) * 2003-06-18 2014-05-22 Robert Bosch Gmbh Method and device for exchanging data via a bus system
GB2404121A (en) * 2003-07-18 2005-01-19 Motorola Inc Inter-network synchronisation
DE102005018837A1 (en) * 2005-04-22 2006-10-26 Robert Bosch Gmbh Method and device for synchronizing two bus systems and arrangement of two bus systems
US9137042B2 (en) * 2006-09-06 2015-09-15 Nxp, B.V. Cluster coupler in a time triggered network
DE102007048860A1 (en) * 2006-11-03 2008-05-08 Robert Bosch Gmbh Device and method for manipulating communication messages

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060143345A1 (en) * 2002-12-17 2006-06-29 Kvaser Consultant Ab Schematizing of messages in distributed control and supervision system
DE102004063213B4 (en) * 2004-12-24 2006-11-23 Pilz Gmbh & Co. Kg Control system with a plurality of spatially distributed stations and method for transmitting data in such a control system
US20060248249A1 (en) * 2005-04-29 2006-11-02 The Boeing Company Systems and methods for multiple input instrumentation buses
DE102005060085A1 (en) * 2005-12-15 2007-06-21 Beckhoff Automation Gmbh Data transmitting method for e.g. Ethernet-network, involves subdividing sending cycle into sub cycles using control unit so that data in form of telegram is communicated between nodes connected to transmission line in each sub cycle

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AT512449B1 (en) 2013-09-15
WO2009089869A1 (en) 2009-07-23
DE102008004854A1 (en) 2009-07-23

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