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    • 专利摘要:
    Communication procedure in can networks and signal concentrator that executes said procedure. The present invention discloses a communication procedure in can networks ("controller area network") and a signal concentrator (3) executing said procedure. More specifically, this signal concentrator (3) for can networks comprises: an input/output module (8), a series of links (2) connected to said input/output module (8), a signal coupler (9), and a masking module (17), which allows a greater ability to detect faults and lower possibilities of blocking communications due to defects in the devices that are part of said network. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2614456A1
    申请号:ES201531737
    申请日:2015-11-30
    公开日:2017-05-31
    发明作者:Manuel Alejandro BARRANCO GONZÁLEZ；Julian PROENZA ARENA
    申请人:Universitat de les Illes Balears；
    IPC主号:
    专利说明:

    COMMUNICATIONS PROCEDURE IN CAN NETWORKS AND SIGNAL CONCENTRATOR THAT EXECUTES SUCH PROCEDURE
    D E S C R I P C I O N
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    OBJECT OF THE INVENTION
    The present invention discloses a communication procedure in CAN networks (acronym for "Controller Area Network") and a signal concentrator (better known by the English expression "HUB") that executes said procedure.
    Specifically, the present invention discloses a communication procedure in CAN networks that has considerable advantages over the communication procedures of known networks such as, for example, a greater capacity for detecting failures and less blocking possibilities. of communications due to defects in the devices that are part of said network.
    BACKGROUND OF THE INVENTION
    20 In the industrial field, especially in applications such as the automotive, aviation or robotics, different communications networks (also called field buses) are used. Through the use of these networks it is possible to transmit information between the different parts of a system. These communications networks can be of different types, depending on the communications protocol they use: CAN, TTP, FlexRay, Ethernet Switch, etc.
    The CAN (Controller Area Network) communication protocol is a protocol widely used in most vehicles and, in addition, its use is widespread in other areas: networks for industrial automation, robots, appliances, etc. This type of protocol and, therefore, this type of network provides robustness and good operation in real time at very low cost.
    However, said CAN communications networks have several problems that are
    caused by the fact that it uses a bus type topology; that is, a unique physical communication line to which each and every one of the nodes is connected.
    One of the problems derived from said topology is the fact that the contributions 5 of each and every one of the nodes are coupled in the physical environment that constitutes the bus; giving rise to a resulting signal such that it is impossible to distinguish in it what is the individual contribution of each node. Specifically, in a CAN bus, all nodes have a quasi-simultaneous view of each bit, where the resulting value of each bit is given by a logical operation between the outputs of each of the nodes.
    10
    In CAN networks, it has been used as a standard that said logical operation is an AND operation, therefore, it is enough that a node transmits a zero so that the result of the logical operation, regardless of what happens in the other nodes is zero. Consequently, when the coupling is performed by an AND operation, a bit value with zero value is called a dominant bit value and, on the contrary, a bit value with value one is called a recessive bit value.
    In the case of other types of networks in which the logical operation is different, for example, an OR gate, the dominant bit would be one and the recessive bit value would be zero.
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    In short, in a CAN bus it is enough that a single node sends a dominant bit value so that all nodes receive that dominant bit; while for all nodes to receive a recessive bit value it is necessary that all of them emit a recessive bit value.
    25 The fact that in the resulting signal that is transmitted through the physical means of CAN it is impossible to distinguish the contributions of each and every one of the nodes, hinders, limits or makes impossible the implementation of devices, mechanisms or tools that need to discern which is the contribution of each of the nodes and, for example in case of a failure in communications, it is very difficult to determine the node that produces them.
    30
    To solve these problems, multiple solutions have been proposed, among which the ones disclosed in Patent ES2253100 and the publication of Manuel Barranco, Julian Proenza, Luis Almeida, "Boosting the Robustness of Controller Area"
    Networks: CANcentrate and ReCANcentrate, "Computer, vol. 42, no. 5, pp. 66-73, May 2009, doi: 10.1109 / MC.2009.145. These two configurations replace the bus with at least one active hub to which the nodes are connected by an uplink (or "uplink") and a downlink (or "downlink") link.The hub receives the contribution of every 5 node through the uplink, couples them via an AND gate and sends the signal resulting from downlinks It is important to note that the signal that the concentrator sends through the downlinks is equivalent to that obtained by a CAN bus as a result of coupling the contributions of all nodes.
    10 The use of two links per node in the applications of said documents makes it possible to physically separate the contribution of each node from the signal that results from coupling all of them. This property allows us to discriminate, bit by bit, what the contribution of each node is and, therefore, allows for the diagnosis of faults more easily than in the case of conventional CAN networks (i.e. CAN networks without active hub) .
    15 However, the types of hubs and networks described by these documents require the use of two separate links (one for upload and one for download) in order to distinguish the contribution of each node. This fact entails a series of disadvantages. The most obvious are a higher cost due to the need to use more hardware; greater difficulty in arranging the wiring; and greater problems when locating the concentrator within the system, since the concentrator brings together a greater number of
    connections and therefore can take up more space than is normally found
    available in applications of this type of networks.
    On the other hand, incompatibility problems can occur with some nodes 25 because, in the networks of the documents described above, each of the nodes needs two transceivers: one to connect to the uplink and another to connect to the downlink and the nodes commercially available, for example, the electronic control units (known by the acronym ECUS) of the English expression Electronic Control Units that operate in the internal networks of the vehicles have a single link
    30 input / output so the application of these systems requires modifications to
    the nodes
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    DESCRIPTION OF THE INVENTION
    In order to solve the problems presented by prior art devices, the present invention discloses a signal concentrator for CAN networks comprising
    • an input / output module with a series of inputs, outputs and inputs / outputs;
    • a series of links to connect the input / output module with a series of nodes; Y
    • a signal coupler with a series of inputs and outputs, where the signal coupler inputs are connected to the outputs of said input / output module, to combine signals received by the inputs into at least one coupled signal.
    Said the concentrator additionally comprises a masking module with a series of inputs, to treat at least one input signal from the nodes and / or the signal coupler, and outputs to send the result generated by treating said input signal to the minus one node, where:
    • at least one of the series of inputs of said masking module is connected to at least one of the series of outputs of the signal coupler;
    • at least one input of the series of inputs of said masking module is connected to at least one of the outputs of said series of outputs of the input / output module;
    • at least one output of said series of outputs of said masking module is connected to at least one input of the series of inputs of the input / output module; Y
    • each link comprises a unique transmission medium that has two-way communication capability to connect the input / output of the input / output module with its corresponding node.
    By coupler it is understood that it is a device that allows combining several input signals and having as output at least one signal dependent on the value of the signals of
    entry.
    In addition, the expression masking should be interpreted in its broadest meaning, that is, modifying a given signal (in this particular case a digital signal) by replacing at least part of at least one of its bits with a masking value , normally a fraction of a dominant bit is replaced by a recessive bit value.
    Additionally, input / output is understood as a port that allows both sending and receiving data or information in a preferred way of signal.
    In particular, in an embodiment of the masking module of the present invention, this comprises a sub-module of selection which, in turn, comprises means for selecting the outputs of the masking module. Said means of selection 15 allow to select for at least one of the outputs of the masking module which is the value of said output, that is to say, preferably allow independent and independent selection for each output of the masking module, if the output of the masking module is a masked signal or a coupled signal.
    As mentioned above, the masking module may have masking means to produce a masked signal from modifying bits of the signal it receives from the coupling module, producing as output a masked or modified signal. Preferably, the masking means for modifying bits of the input signal modifies at least a fraction 25 of at least one dominant bit by a recessive bit value, and vice versa, that is the masking means for modifying bits of the signal of input also modify a fraction of at least one recessive bit by a dominant bit value.
    Additionally, the masking module comprises synchronization means 30 that allow the concentrator to be synchronized both at the bit level and at the frame level with the nodes.
    Preferably, the masking module comprises a controller sub-module.
    with transmission mechanisms to generate and / or retransmit values in a transmitter signal and send it to an input of the signal coupler.
    Additionally, the masking module comprises at least one input 5 capable of specifying to the masking module the value of the masked signal and when selecting it to arrange its output.
    The ability to vary the logical value of fractions of the bit is very important for the invention to work with greater performance. That is, the 10 masking module determines the fractions of the bit that must be modified to achieve several things: (i) know what the contribution that each node transmits, (ii) stay synchronized at the bit level, and / or frame , with the nodes, (iii) make the hub transparent to the nodes (this includes the ability not to disturb the synchronization between the nodes), (iv) to be able to inject specific logical values into fractions of 15-bit time that allow implement error injection mechanisms on the hub.
    As for the input / output module, this can comprise a transceiver for each of the inputs / outputs of the series of inputs / outputs connected to the links so that its function is, basically, to convert the physical signals received in the input / output by signals that can be interpreted by other devices (such as the coupler) as logic signals (ones and zeros).
    In a particular embodiment of the present invention, the selection sub-module comprises selection means that allow the independent selection of 25 for each output, if the same input signal to the masking module from the output is available at the output signal coupler (i.e., the coupled signal) or the masked signal.
    In particular, the selection means may comprise at least one multiplexer and / or a demultiplexer, and the signal coupler is preferably an AND gate. However, these logical elements can be replaced by other devices such as microprocessors, FPGA (from the English expression "Field Programmable Gate Array"), among others.
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    On the other hand, the present invention also discloses a communication procedure by means of the CAN protocol of the signal concentrator, described above, which comprises the steps of:
    a) receive, in the input / output module, at least one signal from at least the nodes through the corresponding link,
    b) transmit to the signal coupler at least one of the output signals of the
    input / output module;
    c) combine, by means of the signal coupler, at least one of the signals
    coming from the output of the input / output module to produce the coupled signal;
    d) transmit the coupled signal and / or at least one of the outputs of the input / output module to the masking module;
    e) produce, by means of the masking module, at least one output signal whose value is selected from the values of the coupled signals, the values of the masked signals generated in the masking module, the values of the masked signals specified in the masking module and signal values of the outputs of the input / output module; Y
    f) send the signals produced in step d) to at least one of the nodes from the input / output module, through the corresponding link.
    In some applications, said method incorporates a stage g) in which the masking module sends any of the signals produced in stage e) to all nodes connected to the input / output module.
    In particular embodiments, in the process of the present invention the masked signal is obtained by modifying at least a fraction of a dominant bit by a recessive bit value, or vice versa, of at least one of the input signals, ie coupled signal or signal of the outputs of the input / output module to the masking module.
    In addition, the coupled signal can be obtained by performing an operation
    Logic of the output signals of the input / output module, for example an AND logic operation.
    As an example, the selection of at least one output signal of the masking module of step e) can be carried out by means of at least one multiplexer and / or a demultiplexer.
    On the other hand, to monitor which node is the one that has made each contribution, the process of the present invention can incorporate a step h) in which a recessive value is sent for at least a fraction of the bit time to any node by the input / output module, and through the corresponding link, and depending on the response of the node it can be determined what contributions it has made. This monitoring aims, mainly to detect faults in the different nodes in a fast way and without incorporating too much technical complexity.
    fifteen
    Additionally, to prevent the links from being permanently blocked at a dominant value when the coupled signal acquires said value, the method of the present invention may incorporate a step i) in which a recessive bit value is sent through the input module / output for long enough for links 20 to regain a recessive value.
    Preferably, at least one recessive value is sent during the bit time by means of the input / output module in such a way that it allows to know the contribution of each of the nodes to which said value has been sent.
    25
    The value of at least one of the signals that the input / output module receives from the masking module can be alternated between the coupled signals, the masked signals and the output signals of the input / output module at least once during the time bit
    30
    Preferably, at least one recessive value can be sent during the bit time by means of the input / output module to prevent reception at the concentrator of a dominant value causing the concentrator to transmit and therefore receive
    permanently a dominant value in each of the links, permanently blocking communications even when all nodes are transmitting a recessive value.
    5 DESCRIPTION OF THE DRAWINGS
    These and other features and advantages of the invention will become more clearly apparent from the following detailed description of the preferred embodiments, given only by way of illustrative and non-limiting example, with reference to the figures that are accompany.
    Figure 1 shows a schematic diagram of a conventional CAN network, that is, in bus topology.
    15 Figure 2 shows a schematic diagram of a CAN network with star topology according to the prior art.
    Figure 3 shows a schematic diagram of a CAN network with star topology according to the present invention.
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    Figure 4 shows a schematic diagram of an example hub for a CAN network according to the present invention.
    Figure 5 shows a schematic view of an example node for a CAN network.
    25
    Figure 6 shows an example scheme of the parts or segments of the bit time of a hub according to the present invention.
    PREFERRED EMBODIMENT OF THE INVENTION
    30
    Figure 1 shows a conventional bus configuration. It is important to note that for this configuration it is that the devices that, for the purposes of this description, are treated as nodes (1) that use the CAN protocol are initially designed.
    This figure 1 shows multiple nodes (1) connected to a bus (10). As explained above, this configuration has several disadvantages, among which it is very difficult for a monitoring element (11) to determine without a doubt the individual contribution of each of the nodes (1). In fact, complex algorithms for detecting said contribution are required to be able to determine the area of the bus (10) in which the fault occurs.
    Figure 2 shows a first proposed solution in which the topology of
    10 connection of the nodes (1) and passed from a bus topology (as described
    previously referring to figure 1) to a star topology. In this topology each of the nodes (1) is connected individually to a hub (3) by means of a unidirectional link (20). This unidirectional link (20) in the embodiments of the prior art is a double unidirectional link (20) comprising a link
    15 unidirectional rise (20 ’) and a unidirectional downlink (20’) known in the
    industrial communications sector such as "uplink" and "downlink" respectively. More specifically, this unidirectional uplink link (20 ') or "uplink" goes from the hub (3) to the node (1), while the unidirectional downlink link (20' ') goes from the node (1) to the concentrator (3).
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    The solution of Figure 2 has, among others, the disadvantage that commercially available nodes (1) do not have said unidirectional uplink links (20 ’) and unidirectional downlink links (20’). On the contrary they have a single simple link for the transmission and reception of data. Consequently, to apply the solution of Figure 25 2 it is required to modify the commercially known devices to conform to this
    New topology
    Figure 3 shows, schematically, a network according to the present invention. In this network each of the nodes (1) is connected by a single link (2) to a hub 30 (3). The present invention discloses a concentrator (3) that conforms to the conditions
    of the commercial nodes (1) without requiring any modification in their physical structure, that is, they are fully compatible.
    Figure 4 shows, in greater detail, the structure of said concentrator (3) to solve the problems of the prior art.
    To facilitate the explanation of the present invention, in the embodiment of Fig. 4, a concentrator (3) for two nodes (1) is described by way of example, although extrapolation of this same concentrator (3) is evident for its operation with a greater number of nodes (1).
    Figure 4 shows that, as input / output to the hub (3) there are two links 10 (2) with two-way communication capability (that is, the hub (3) can send
    and receive information through the same link (2). These links (2) are connected to nodes (1) and through said links (2) physical electrical signals are arranged that should be arranged as logical signals for further processing in the concentrator (3), consequently, said physical signals are they pass through an input / output module 15 (8) that converts these physical signals into logical signals giving certain uniformity to the signals.
    This example of input / output module (8) comprises a transceiver (6) for each of the links (2) (and, consequently, for each of the nodes (1).
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    On the other hand, the concentrator (3) comprises a signal coupler (9) and a masking module (17).
    As for the signal coupler (9) it is a module that receives the signals coming from each of the nodes (1) and that have been passed through the input / output module (8) to facilitate its treatment, that is, in said input / output module (8) they have been converted into logical signals. This signal coupler (9) has the function of taking the multiple signals coming from the nodes (1) and coupling them in a coupled signal (14). In the particular embodiment of the figure, this coupling is carried out by means of a logical AND operator (16).
    As for the masking module (17), in a preferred embodiment it comprises two sub-modules: a signal processing sub-module (12) and a sub-module of
    selection (18).
    The signal processing sub-module (12) has, as inputs, the coupled signal (14) coming from the coupler (9) and the signals coming from each of the nodes (1) 5 converted to logic signals after passing by the input / output module (8) so that the signal processing sub-module (12) has, on the one hand, the information of the coupled signal (14) and, on the other, has for each node ( 1) of a signal in which you can know, applying the procedure disclosed in this invention, the individual contribution made by that node (1) in each bit.
    10
    As outputs of this signal processing sub-module (12), a masked signal (15) is obtained which, basically, is the coupled signal (14) in which at least part of at least one of its bits has been modified. In addition, output selection signals (26) are arranged as outputs by means of which it is independently determined for each node (1), if the output to be arranged is the coupled signal (14) or the masked signal (15 ). In some preferred embodiments, a single output selection signal (26) is available by which it is determined whether the output signal (13) of the masking module (17) is available, and therefore sent to all nodes (1), is the coupled signal (14) or the masked signal (15) ”.
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    This masking is particularly relevant in the present invention in that, in a conventional CAN network, all nodes (1) receive from the medium (the bus) a dominant value while a dominant value is being transmitted to the medium (to the bus). The coupled signal (14) calculated by the concentrator (3) of the present invention behaves in the same way as the bus, in the sense that the value of the coupled signal (14) is
    dominant while a dominant value is being transmitted to the medium (in this case to one of the links (2). Therefore, it is sufficient that the concentrator (3) receives from a node (1) a dominant value for the coupled signal (14) is dominant and, as a consequence, so that the concentrator (3) transmits a dominant value through all links (2) In this situation, the concentrator (3) receives and therefore transmits
    permanently a dominant value in each of the links (2), blocking
    permanently communications, even when all nodes (1) are transmitting a recessive value. This type of situation is known in the art for English expression
    "infinite loopback."
    To prevent the "infinite loopback" of a dominant bit value from occurring, the signal that the hub (3) sends to the nodes (1) is not always the coupled signal (14). Instead of that, in certain moments of the bit time, the concentrator (3) of the present invention does not send the coupled signal (14) but a recessive bit value; that is to say the concentrator (3) masks (by means of the signal processing sub-module ( 12) the coupled signal (14) with a recessive bit value More specifically, we will refer to this signal that the concentrator (3) sends during masking (whose bit value is 10 recessive although the bit value of the coupled signal (14) be dominant) as masked signal (15).
    In short, to prevent an "infinite loopback" from occurring, the hub (3) checks at the beginning of each current bit if the value that it samples in the coupled signal (14) 15 in the previous bit was dominant. If so, the hub (3) stops sending (masking) the coupled signal (14) at the beginning of the "current" bit time and instead sends the masked signal (15) (a recessive value) through all its links ( 2). The concentrator (3) keeps sending this recessive value for long enough so that, in the event that all nodes (1) want to send a recessive value in the "current" bit, 20 that recessive value is reflected in the coupled signal (14) and, consequently, on all links (2).
    The signal processing sub-module (12) has the function of selecting whether each coupled node (1) is sent the coupled signal (14) or the masked signal (15). In particular, this signal processing sub-module (12) also allows to select whether for each specific node (1) a recessive bit value is sent to determine its contribution in one or each of the bits that compose Network traffic. Once the signal to be sent to any node (1) has been selected, the signal processing sub-module (12) communicates its decision to the selection sub-module (18) by means of the 30 output selection signal (26) corresponding.
    This sending of a recessive bit value individually to each node (1), or together to a group of nodes (1), allows to distinguish the contribution of a node
    anyone. With this objective, the signal processing sub-module (12) masks with a recessive value for part of the bit time (28) the coupled signal (14) on the link (2) corresponding to that node (1). In this way, the concentrator (3) is able to sample, on the link (2) corresponding to said node (1) and determine the bit value it is transmitting. That is, apart from masking to avoid "infinite loopback", the signal processing sub-module (12) performs a second masking during part of the bit time. We will refer to this second masking as monitoring masking. Specifically, during this second masking, the concentrator (3) also stops sending it to the node (1) or to the nodes (1) 10 whose contribution it wants to monitor the coupled signal (14) and, instead, it sends or sends the masked signal ( 15) (a recessive bit value) through its link (2) As a consequence, the concentrator (3) does not force any value on each link (2) on which it is applying the monitoring masking, but the value reflected on each link (2) depends solely on the value that the corresponding node (1) 15 is actually transmitting, so if during the monitoring masking a node (1) is transmitting a recessive bit value, said value of bi Recessive t will be observed in your link (2). Analogously, if during this masking a node (1) is transmitting a dominant, said dominant will be observed in its link (2).
    20 It is important to keep in mind that from the moment the concentrator (3) starts monitoring masking, until the moment when the value transmitted by the node (1) whose contribution is to be monitored is reflected in the signal (29) a certain amount of time elapses from entering the signal processing sub-module (12). Therefore, the concentrator (3) must maintain the monitoring masking for the time necessary to be able to observe the contribution of each node (1) in the corresponding signal (29) of the concentrator (3). Once the concentrator (3) has waited long enough for the contribution of a node (1) to be reflected in the corresponding signal (29) of the concentrator (3), monitoring is carried out. Preferably, the concentrator (3) of the present invention applies the monitoring masking 30 simultaneously on the link (2) of each and every one of the nodes (1); then wait for the contributions of each and every one of them to be reflected in the corresponding ports of the hub (3); and then sample each of those contributions at the same time.
    Once the hub (3) has sampled the contribution of a node (1), it can unmask the coupled signal (14) on the link (2) of that node (1); If you can, you can undo the monitoring masking and reset the coupled signal (14) to that node (1). To do this, the concentrator (3) transmits again via the link (2) of that node (1) the coupled signal (14) instead of transmitting the masked signal. Preferably the concentrator (3) of the present invention unmasks the coupled signal (14) (ends the monitoring masking) on all the links (2) at the same time.
    10 Due to its ability to distinguish and sample the contribution of each node (1), the concentrator (3) of the present invention has the characteristic that, for each node (1) that is connected to it, it provides a logical signal in which specifies the contribution of that node (1) (recessive bit value or dominant bit value) for each bit that constitutes the network traffic. We will refer to each of these signals as “monitored contribution 15” of the corresponding node (1). The existence of these signals allows to implement devices, mechanisms or tools that need to discern what is the contribution of each of the nodes (1) in each bit of the traffic of a CAN network.
    Therefore, the present invention is capable of providing all the advantages described so far, while maintaining all the basic characteristics and properties of a conventional CAN network.
    First, from the point of view of the nodes (1), the hub (3) behaves like a conventional CAN bus in which the contributions of all nodes (1) are coupled in such a way that the bits keep its recessive and dominant character.
    Second, the present invention retains the property of CAN known as "inbit response." This property is that each and every one of the nodes (1) has a quasi-simultaneous vision of each bit that constitutes the traffic that is transmitted in the network. The present invention retains the property of in-bit response because the coupling and masking performed by the concentrator (3) as well as the operations of the input / output module (8), are performed in a fraction of time significantly less than time
    that lasts a bit in the CAN protocol.
    In addition to controlling how and when masking is performed, the signal processing sub-module (12) can also perform other functions such as, for example, having 5 for each of the nodes (1) connected to the concentrator (3), a contribution signal (19) in which it specifies the contribution of that node (1) (recessive bit value or dominant bit value) for each bit that constitutes the network traffic. Although in Figure 4 only two contribution signals (19) have been included, as many contribution signals (19) as nodes (1) can be incorporated into the network.
    10
    These contribution signals (19) must be updated in each new bit that is transmitted, since the contribution of each node may be different in each bit. Preferably, in each bit, the signal processing sub-module (12) samples each of the signals coming from the links during monitoring masking
    15 (2). At the end of the monitoring masking, the treatment sub-module of
    signals (12) have already sampled all signals, determined the contribution of each of the nodes (1) and, therefore, can update the logical value of the contribution of each node (1) in the contribution signal (19) corresponding.
    20 Analogously, the signal processing module (12) can also provide a logic signal in which it specifies, bit by bit, what is the value of the coupled signal (14). We will refer to this signal as a monitored coupled signal (30). That is, for each bit that is transmitted in the network, the signal processing module (12) indicates in this monitored coupled signal (30) the logical value (recessive or dominant) that, in the absence of
    25 errors, each and every one of the nodes (1) must have sampled (and therefore received). In this sense, it can be said that the signal processing sub-module (12) provides the concentrator (3) with the possibility of observing the network traffic in the same way as a node (1) does.
    30 Taking advantage of its ability to stay synchronized at the bit and / or frame level with the coupled signal, the signal processing sub-module (12) is also capable of generating as many clock signals, as necessary, to indicate when it starts each of the parts in which it divides the bit time. Of all these possible clock signals, the
    three that have a greater interest are, for example: a monitoring clock signal (21), a reception clock signal (22) and a transmission clock signal (23).
    Preferably, the monitoring clock signal (21) is activated once in each 5-bit time (28) to indicate that the contribution signals (19) have already been cooled and, that by
    therefore, they already reflect the contribution of each of the nodes (1) for the bit that is being
    currently broadcasting. This monitoring clock signal (21) can be used by any module or device connected to (or included in the) hub (3) to know when you can check the values of the contribution signals (19).
    10
    Regarding the reception clock signal (22), it is activated once in each bit to indicate that the value of the coupled signal (14) has already been sampled by the signal processing sub-module (12). That is, the reception clock (22) is activated to indicate that the monitored coupled signal (30) already reflects the logical value of the bit being
    15 currently transmitting on the coupled signal (14). In this regard, the clock signal of
    reception (22) is analogous to the reception clock generated by a standard CAN controller and, therefore, indicates the moment when the coupled signal (14) has already been sampled safely to obtain the same bit value as the nodes (1 ) observe after making their own sampling. Thus, the reception clock signal (22) can be used by any module or device connected to (or included in the) hub (3) that wishes to monitor, bit by bit, the traffic that the nodes should be receiving ( one).
    Finally, the transmission clock signal (23) is activated at the beginning of each new bit time. This behavior is analogous to that of the transmission clock (23) that generates a standard CAN controller, which indicates the moment at which the CAN controller starts the transmission of each new bit. In the case of the concentrator (3), the transmission clock signal (23) allows to implement mechanisms that transmit from the concentrator (3) as if it were a node (1).
    In other preferred embodiments of the present invention, the masking module (17) may also comprise more complex mechanisms for error detection. These mechanisms are arranged in a controller sub-module (24).
    This sub-module controller (24) can include different mechanisms of the MAC layer (of the English expression, Medium Access Control) of CAN, according to the needs. Specifically, in a preferred embodiment of the present invention a mechanism is included that is capable of interpreting what is the bit and the field of the frame being transmitted in the coupled signal (14); which is capable of detecting in said signal the same types of errors that a CAN controller detects but at the MAC layer level (for example, those known in CAN communications as bit error, stuff error, format error, error of public redundancy (CRC) and acknowledgment error (ACK)); and that it is capable of signaling and globalizing these errors as if it were a standard (1) CAN 10 node.
    To be able to signal and globalize the errors, it is necessary to be able to transmit on the coupled signal (14). Therefore, preferably, the controller sub-module (24) generates a transmitter signal (25) connected to an input of the signal coupler (9), linked with 15 of the logic operator AND (16), by which it can " inject ”or transmit bits to the coupled signal (14).
    Figure 5 shows, schematically, the operation of a node (1) connected to the hub (3). For this, each node (1) preferably uses a CAN controller (5) and a node transceiver (7) to connect to a certain link (2). The transmission output (71) of the CAN controller (5) is connected to the transmission input of the node transceiver (7); while the reception input (72) of the CAN controller (5) is connected to the reception output of the node transceiver (7). Finally, a microcontroller (4) is connected to the CAN controller (5) through the relevant input and output ports (50). Although it would also be possible to use a microcontroller
    (4) with at least one integrated CAN controller (5); or connect the microcontroller (4)
    with the CAN controller (5) via the external memory bus of the microcontroller (4).
    Figure 6 shows the parts or segments in which preferably the
    30 concentrator (3) considers that the bit time (28) is divided. Notice what I know
    shown in figure 6 is the way in which preferably the concentrator (3) structures the bit time (28). In this regard it should be noted that in the present invention preferably the CAN controllers (5) of the nodes (1) continue to consider that the bit
    It is divided into the same segments specified in the CAN standard.
    As an example, the hub (3) defines that the bit time (28) is divided into the following segments: SYNC_SEG (281), PREMASK_SEG (282), MASK_SEG (283), 5 RESTAB_SEG (284) and PHASE_SEG2 (285 ).
    SYNC_SEG (281) is defined as equivalent to the segment that has the same name in the CAN standard. That is, SYNC_SEG (281) is the initial segment of the bit time (28) and, therefore, the hub (3) and the nodes (1) expect to observe in that segment any 10 flank (recessive-to-dominant or dominant) -a-recessive) produced by the start of the transmission of a new bit whose polarity is opposite to that of the previous bit.
    PREMASK_SEG (282) and MASK_SEG (283) are the two segments that follow the SYNC_SEG (281). These two segments do not exist from the point of view of nodes 15 (1), but only from the point of view of the hub (3).
    PREMASK_SEG (282) is used to apply masking that avoids "infinite loopback" when necessary, as well as to wait for the time it takes before applying monitoring masking. MASK_SEG (283) is used 20 to carry out monitoring masking.
    Preferably, and as shown in Figure 6, the end of the monitoring masking marks the end of the MASK_SEG segment (283), so that the RESTAB_SEG segment (284) is then given step.
    25
    The purpose of the RESTAB_SEG segment (284) is to wait the necessary time to ensure that each and every one of the nodes (1) can sample the logical value that you want to send. For example, the RESTAB_SEG segment (284) allows waiting for the necessary time to ensure that each and every one of the nodes (1) to which it is desired to send the coupled signal (14) again observes the logical value of that signal ( 14) with enough anticipation to be able to sample it correctly.
    The last segment that preferably composes the bit time (28) is PHASE_SEG2 (285). The role of this segment is equivalent to the segment that bears the same name
    in the CAN standard; that is, to compensate for the differences between the local clocks of the nodes (1). Specifically, it serves to prevent a node (1) that observes a new bit value before what the SYNC_SEG segment (281) considers, to sample that new value and take it as the value of the current bit.
    5
    The concentrator (3) of the present invention is characterized by the fact that it is capable of lengthening or shortening the different segments of the bit time (28) in order to resynchronize with the nodes (1) of the network.
    10 The characteristics and description of the bit time (28) will be more evident in view of
    the explanation of figure 7.
    Figure 7 shows a flow chart, by way of example, of how an example of a hub (3) according to the present invention uses the different 15-bit time segments (28) to carry out the masking.
    This diagram shows how the first stage (701) carried out by the concentrator (3) along the bit time (28) consists in starting the first segment (SYNC_SEG (281)). Subsequently, the concentrator (3) terminates (702) this segment (281) and evaluates a first logical decision element (703), in which it is determined whether the value that the concentrator (3) detected in the coupled signal (14) during the previous bit it was dominant.
    If so, proceed to step (704) in which two actions are executed: on the one hand, the concentrator (3) starts the next bit time segment, that is, the PREMASK_SEG segment (282) and, on the other hand, the concentrator (3) starts masking to avoid “infinite loopback.” As explained above, this masking to avoid “infinite loopback” consists of sending a masked signal (15) (or a value recessive) to all nodes (1), Alternatively, the masked signal (15) can be sent only to the links (2) that have a dominant value.
    In the case where the first logical decision element (703) has not been detected or
    Sampling a dominant value in the coupled signal (14) during the previous bit, proceed to step (705) in which the concentrator (3) starts the next segment (PREMASK_SEG (282)) without masking.
    5 Subsequently, a second logical decision element (706) is passed in which it is determined whether enough time has passed so that, in case of having sent a recessive value in the previous stage (704), a recessive value is observed in the signals (29) of the concentrator (3) corresponding to all those nodes (1) that are sending a recessive value.
    10
    If yes, proceed to the next stage (707) in which the concentrator (3) starts the next segment (MASK_SEG (283)) and the concentrator (3) starts monitoring masking by transmitting a bit value recessive to at least one of the nodes (1). As explained above, preferably, this recessive bit value 15 is sent to all nodes (1).
    In the case where in the second logical decision element (706) it is determined that not enough time has elapsed, the concentrator (3) is maintained in this second logical decision element (706).
    twenty
    Next, a third logical decision element (708) is passed in which it is determined whether enough time has elapsed so that the actual contribution of each node (1) to be monitored can be read on the corresponding port of the hub (3 ). If not enough time has passed, the concentrator (3) is maintained in this third logical decision element 25 (708)
    If so, we proceed to a sampling stage (709) in which the concentrator (3) samples (that is, reads) the contribution of each of the nodes (1) to which the bit value has been transmitted recessive in the one stage (707) above.
    Subsequently it proceeds to the next stage (710) in which the concentrator (3) passes to the next segment (RESTAB_SEG (284)), ends the monitoring masking and restores the value of the signal that is transmitted to each node (1) before of this
    masking In this preferred embodiment at the end of the monitoring masking, the coupled signal (14) is transmitted to all nodes (1).
    Subsequently, the concentrator (3) proceeds to execute a fourth decision element 5 logic (711) in which it is determined whether enough time has passed so that each node (1) can read the value of the signal that it wants to send . In this preferred embodiment, by means of the logical decision (711), it is determined whether enough time has elapsed for the value of the coupled signal (14) to be read by each node (1). In case there has not been enough time, the Concentrator (3) is maintained in this fourth element of logical decision (711).
    If so, the concentrator (3) goes to the next stage (712) in which the PHASE2_SEG bit time segment (284) starts, proceeds to a new stage (713) in which the coupled signal (14) is sampled ) to obtain the same value of the resulting bit that the nodes (1) to which the coupled signal (14) has been sent are observed, subsequently, it executes a last stage (714) in which this last bit segment PHASE2_SEG ends (284).
    权利要求:
    Claims (15)
    [1]
    5
    10
    fifteen
    twenty
    25
    30
    R E I V I N D I C A C I O N E S
    1. Signal concentrator (3) for CAN networks comprising:
    • an input / output module (8) with a series of inputs, outputs and inputs / outputs;
    • a series of links (2) intended to connect the input / output module (8) with a series of nodes (1); Y
    • a signal coupler (9) with a series of inputs and outputs, where the inputs of the signal coupler (9) are connected to the outputs of said input / output module (8), to combine signals received by the inputs in at least one coupled signal (14);
    characterized in that the concentrator (3) additionally comprises a masking module (17) with a series of inputs, to treat at least one input signal from nodes (1) and / or signal coupler (9), and outputs to send the result generated by treating said input signal to at least one node (1), where:
    • at least one of the series of inputs of said masking module (17) is connected to at least one of the series of outputs of the signal coupler (9);
    • at least one input of the series of inputs of said masking module (17) is connected to at least one of the outputs of said series of outputs of the input / output module (8);
    • at least one output of said series of outputs of said masking module (17) is connected to at least one input of the series of inputs of the input / output module (8); Y
    • each link (2) comprises a unique transmission medium that has two-way communication capability to connect the input / output of the input / output module (8) with its corresponding node (1).
    [2]
    2. Signal concentrator (3), according to claim 1, characterized in that the masking module (17) comprises a selection sub-module (18) with selection means allowing selection, for at least one of the signals ( 13) of the outputs of the masking module (17), which is the value of said signals (13).
    5
    10
    fifteen
    twenty
    25
    30
    35
    [3]
    3. Signal concentrator (3), according to claim 1, characterized in that the masking module (17) has masking means to produce at least one masked signal (15) from the modification of at least one part of at least one of the bits of at least one of the input signals (14,19) to the masking module (17).
    [4]
    4. Signal concentrator (3), according to claim 1, characterized in that the masking module (17) comprises synchronization means that allow the concentrator (3) to be synchronized at bit level and / or frame level with the nodes (one).
    [5]
    5. Signal concentrator (3) according to claim 1 characterized in that the masking module (17) comprises a controller sub-module (24) with transmission mechanisms to generate and / or transmit values in a transmitting signal (25) and send it to an input of the signal coupler (9).
    [6]
    6. Signal concentrator (3), according to claim 1, characterized in that the inputs and outputs of the masking module (17) additionally comprise at least one input capable of specifying to the masking module (17) the value of at least one of the masked signals (15) and when selected to be arranged in at least one signal (13) at the outputs of the masking module (17).
    [7]
    7. Signal concentrator (3) according to claim 1, characterized in that the input / output module (8) comprises a transceiver (6) for each of the links (2).
    [8]
    8. Signal concentrator (3) according to claim 2, characterized in that the selection means comprise at least one multiplexer and / or at least one demultiplexer.
    [9]
    9. Signal concentrator (3) according to claim 1, characterized in that the signal coupler (9) comprises at least one logical AND operator (16).
    [10]
    10. A CAN protocol communication method of a signal concentrator (3) described in any one of the preceding claims, characterized in that it comprises the steps of:
    a) receive, in the input / output module (8), at least one signal from to
    25
    5
    10
    fifteen
    minus one of the nodes (1) through the corresponding link (2),
    b) transmit to the signal coupler (9) at least one of the signals (29) of
    output of the input / output module (8);
    c) combine, by means of the signal coupler (9), at least one of the signals
    (29) output of the input / output module (8) to produce the coupled signal (14);
    d) transmit the coupled signal (14) and / or at least one of the output signals (29) of the input / output module (8) to the masking module (17);
    e) produce, by means of the masking module (17), at least one output signal (13) whose value is selected from the values of the coupled signals (14), the values of the masked signals (15) generated in the module masking (17), the values of the masked signals (15) specified in the masking module (17) and the values of the signals (29) of the outputs of the input / output module (8); Y
    f) send the signals (13) produced in step e) to at least one of the nodes (1) from the input / output module (8), through the corresponding link (2).
    20 11. Method according to claim 10, characterized in that it comprises a
    step g) in which the masking module (17) sends at least one output signal (13) produced in stage e) to all nodes (1) connected to the input / output module (8).
    12. Method according to claim 10, characterized in that at least one signal
    masked (15) is obtained by modifying at least a fraction of a dominant bit by a recessive bit value, or vice versa, of at least one of the input signals (14, 29) to the masking module (17).
    30 13. Procedure, according to claim 10, characterized in that at least one signal
    coupled (14) is obtained after a logical operation of the output signals (29) of the input / output module (8).
    [14]
    14. Procedure, according to claim 13, characterized in that said operation
    Logic is an AND logical operation.
    [15]
    15. Method according to claim 10, characterized in that the selection of the value acquired by each output signal of the masking module (17) of step e)
    5 is performed by at least one multiplexer and / or a demultiplexer.
    [16]
    16. Procedure, according to claim 10 characterized in that it comprises
    additionally a step h) in which at least one recessive value is sent to at least one of the nodes (1) by means of the input / output module (8) and through the link (2) to
    10 know the contribution of each of the nodes (1) to which said value has been sent.
    [17]
    17. Procedure, according to claim 16, characterized in that the value of at least
    one of the signals that the input / output module (8) receives from the module
    masking (17) can be alternated between the coupled signals (14), the signals
    15 masked (15) and the output signals of the input / output module (8) at least once during the bit time.
    [18]
    18. Procedure, according to claim 10, characterized in that it comprises
    additionally a stage i) in which at least one recessive value is sent to at least one
    20 of the nodes (1) through the input / output module (8) and through the link (2) to prevent reception at the concentrator (3) of a dominant value causing the concentrator (3) to transmit and therefore permanently receive a dominant value in each of the links (2), permanently blocking communications even when all nodes (1) are transmitting a recessive value.
    25
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    ES2614456B2|2017-09-18|
    WO2017093585A1|2017-06-08|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US20110103390A1|2009-10-30|2011-05-05|Honeywell International Inc.|Serialized enforced authenticated controller area network|
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