FR2828964A1 - ELECTRONIC SYSTEM COMPRISING A LIGHT CONDUCTOR NETWORK AND AUTOMATIC CONTROL METHOD - Google Patents

Abstract

Multi-node electronic system (100, 200, 300, 400, 500, 600) connected by light guides (2, 3, 4, 5, 6) to form a network characterized in that each node comprises: - means for transmitting information with a reduced transmission power to each of its neighbor nodes, - means for receiving a confirmation of the reception of the information by the neighboring node concerned, - means for transmitting a fault signal to the node bus management (100) in case confirmation has not been received.

Description

The present invention relates to a multi-node electronic system

  combined in a network by light guides and a method and computer program for automatic control

of this electronic system.

  According to the state of the art, various processes are known

  and light guide control systems.

  EP-A-823 621 discloses a light guide transmission path having a large number of refraction gates along the light guide for detecting the position of a defect. Reflective elements reflecting different wavelengths can be distributed over the waveguide transmission path for

  detect, with greater precision, the position of a fault.

  According to DE 698 00438 T2, there is known a more developed system in which a possible defect can be located in an optical element by emitting a signal in the optical element for measuring the signals reflected by the reflection events and comparing the reflected signals measured at predictable signals corresponding to

  a non-defective optical element.

  According to the document of 695 19 990 T2, a procedure is known

  o fault location in optical transmission systems.

  According to this method, a defect localization device is used by the refraction measurement technique which uses the statistical properties to exploit a sequence of transmitted and reflected data in the downward direction. s Optical transmission systems are also used in motor vehicles, for example in

  bus according to the MOST standard and the IEEE 1394 standard.

  The use of the IEEE 1394 standard makes it possible to create a serial bus system in which the different nodes of the network are connected by means of light guides. This standard provides for self-configuration of the network, that is, after the connection or after the reset, all the nodes send some information selected by themselves in the network. This information is received by all nodes. A node can be designed to perform additional management functions

  3s for network bus management.

  For this purpose, the node concerned collects all the information from the other nodes, processes it and memorizes it internally. In the case where several nodes with bus management capability exist in the network, a competition method is provided according to which one of the nodes appears as master and then provides the management of the bus. The bus management nodes thus decide, for example, the power supply, activity and occupation of the bus by the different nodes; the management node also provides information about the network topology and

transmission speeds.

  The IEEE 1394a and IEEE 1394b standards are extensions of the IEEE 1394 standard, especially for motor vehicle applications. The corresponding standards can be found in the following document <The Institute of Electrical and Electronics Engineers, Inc., 345 East 47th Street, New York, NY 10017

2394; USA ".

  Particularly for applications in the automotive field, the permanent availability of network functions is of great importance and this for the various applications in motor control fields, ie electronic circuits. as well as for applications in information technology and

of multimedia.

  The object of the present invention is therefore to develop an electronic system and a better method for automatically testing a computer.

bucket with light guide.

  The problem underlying the invention is solved by a system characterized in that each node comprises: means for transmitting information with reduced transmission power 2s to each of its neighbor nodes; means for receiving a confirmation of the receipt of the information by the neighbor node concerned, - means for sending a fault signal to the management node

  bus in the absence of receipt a confirmation.

  The present invention is based on the consideration that generally light guides are not abruptly defective but that their optical characteristics may deteriorate over time and the nature of the deterioration of transmitted characteristics.

  Optical sion can also depend on the frequency.

  The present invention avoids network failure by diagnosing the deterioration of a transmission characteristic of a light guide link long before the failure or

  disruption of operation by automatic diagnosis.

  According to a preferred embodiment, such an automatic control test is performed in that a certain node of the network transmits information with a reduced transmission power compared to the normal transmission power. For example, the reduction of the transmit power can be 3 dB or 6 dB. The reception of information with a reduced transmission power is also acknowledged by the reception node, by an acknowledgment of receipt. This acknowledgment is equal

  sent back by a light guide.

  The confirmation is preferably transmitted with a normal transmit signal. But the confirmation may also have been transmitted with reduced transmit power to test the feedback link. According to another preferred embodiment, information is transmitted again with a reduced transmission power if, within a predetermined period, there has been no confirmation of receipt of the information. . The repeated transmission of the information could be done with an increased power step by step to see to what

  transmission power is the transmission of information.

  In the event that no confirmation of receipt of the information by the node issuing the information has been received or only after stepwise increase of the reduced transmission power, the node concerned issues a fault signal. This fault signal can be described as a parameter, the amplitude of the reduced transmission power, which

has been increased step by step.

  According to a preferred embodiment of the invention, the fault signals are stored by a bus management node. From the fault signals, it is then possible to automatically generate a maintenance plan. For example, during the next inspection, the relevant light guides which have a limited optical transmission characteristic can be replaced, in a preventive manner, without the user of the vehicle being able to perceive a disturbance in operation or

even be broken down.

  According to another preferred embodiment of the invention, an automatic test is started by an automatic 3s procedure if the network is in a reduced state of charge. For example, we start an automatic test when the ignition is off. It is possible, for example, to perform such an automatic test by repeating it cyclically in predetermined time intervals while the ignition is in progress.

is cut.

  According to another preterential embodiment, it is

  Means an automatic test by sending an automatic test command by the bus management node to all nodes of the network to put these nodes in an appropriate mode. Alternatively, the bus management node

  sends only automatic test information to the nodes

  exactly neighbors. This automatic test information then passes the nodes directly adjacent to the bus management node in the automatic control mode. These nodes directly neighbors the management node

  However, the buses transmit the automatic test information to

  neighboring nodes, so that they are also in

  automatic test. This distributes the automatic test information

than in the entire network.

  According to another preferred embodiment of the invention, the power of a node which has led to a fault signal is increased beyond the normal transmission power. This allows, for example, to compensate even temporarily a greater damping of the corresponding light guide, until replacement of

  this light guide during the next maintenance operation.

  An example of a preferred embodiment of the invention will be described in more detail below with reference to the accompanying drawings in which: FIG. 1 shows a block diagram of a preferred embodiment of FIG. An electronic system according to the invention, - Figure 2 shows an embodiment of a method according to the invention of automatic test (automatic control), - Figure 3 shows a flow chart of an embodiment of the process according to the invention in which the automatic test is triggered by an automatic test command issued by the bus management node, - Figure 4 shows an embodiment of the method according to the invention for which the automatic test is triggered by information automatic test from the bus management node,

  FIG. 5 shows an alternative embodiment of the method of FIG. 4.

  FIG. 1 shows a network 1 with nodes 100, 200, 300, 400, 500 and 600. The nodes can be the most different network elements and automotive electronics as well as for applications in the field of telecommunications. information, entertainment and multimedia. In the exemplary embodiment of FIG. 1, the network 1 corresponds to the IEEE 1394 standard, for a serial bus system. This standard makes it possible for example to connect the different nodes of the network by a cable

  to 4 up to 6 strands or a light guide.

  In the embodiment of FIG. 1, the nodes 100 600 are connected by light guides 2-6. It may however be a pair of light guides for direct transmission and return transmission; it may also be a single light guide for which different transmission frequencies are used for the trans

  o direct mission and return transmission.

  The different nodes 100-600 each have a microprocessor with different ports to connect the light guides. Only one port has an entry and an exit. For the emission, photodiodes are preferably used because they are particularly economical. To achieve the light guides, it is possible to use glass fibers or

plastic fibers.

  The network 1 uses a self-configuration method, as specified in the IEEE 1394 standard, that is to say that one of the nodes 100 600 provides, during the initialization phase of the network 1, the function of bus management. In the example of FIG. 1, it is the node that performs the function of bus management node. This node 100 is

  also responsible for managing the network.

  The bus management node 100 includes a memory for the network topology 1, i.e. the information describing the different nodes of the network and their connections. In addition to the network management functions, the bus management node performs the function

  initialization and operation of an automatic test.

  To launch such an automatic test, the bus management node informs, using a determined order sent throughout the network or in a dedicated manner or automatic test information to the nodes, for them to reduce the optical transmission power for a limited time. After receiving this recommendation to transmit with reduced transmission power, the different nodes see special data packets to all the ports to which devices are connected. The correct reception of these packets is again confirmed by a special data packet. If there is no confirmation, it is particularly advantageous to reissue the paquet for a new check. If, on this occasion, or during other repetitions, there is no confirmation, the initialised device sends a

  fault signal at the bus management node.

  Such a fault signal contains information relating to the light guide concerned which has caused the fault signal. I1 left

  advantageously that, first of all, the fault signal but also

  confirmation is transmitted with transmission power

  normal, that is, when a node sends the particular data packet

  only for control with reduced power.

  If a bus management node does not receive a signal from

  o default, because of the particular properties of the connection by guide of lu-

  the general deterioration, slow, of the transmission properties, it is possible to record a defect image sufficiently in time and to inform, during the next maintenance operation, the technician or the user, that the transmission properties are poor and that there is a risk of future failure. In addition, it is possible to increase the transmission power in a determined way to ensure

The compensation.

  Figure 2 shows a corresponding state diagram of nodes 100, 200, 300 (see network 1 of Figure 1). The other nodes of FIG. 1 have not been represented in the diagram of FIG.

reasons for simplification.

  To initiate the self-test, the bus management node sends an automatic test command ("Link_Check_Mode") to all nodes in the network to start an automatic test. This can be

  do at any time. However, it is particularly

  to launch the automatic test procedure when the network is not

  only in reduced load or when cut. In the application to a vehicle

  This is particularly the case when the ignition is off.

  The automatic test order contains as parameter, so the amplitude according to which it is necessary to reduce the power of emission in

  the different nodes. In the exemplary embodiment considered, the parameter

be 3 dB.

  After receiving this automatic test command, all the nodes in the network send information, for example a packet of

  special data to test the corresponding links with a

  reduced. This information is sent by each of the nodes of the network to all the nodes directly neighbors of this node. The reception of the information is then confirmed by each receiver with a confirmation issued with a normal power which guarantees the control

  accurate of each link in both directions.

  If within a predetermined time no confirmation has been received, the information is reissued. This is preferably done with a transmission power increased by one step. If this repeatedly transmitted information does not receive a confirmation, then the initiating apparatus sends a fault signal to the bus manager indicating

  the link that did not work completely.

  This situation is presented in connection with the diagram

  o state of Figure 2: bus management node 100 sends an informa-

  link test test (N Link_Test.) to the nearest neighbor node 200

  of the bus management node 100. Also, the bus management node

  track such information "Link_Test" to the same number 600

  neighborly (see Figure 1); however, this situation is not

  s shown in Figure 2 for reasons of clarity.

  The node 200 sends the information "Link_Test" to the nodes

  directly neighbors 100, 300, 400; only the "Link_Test" information

  to 300 is shown in FIG.

  route the "Link_Test" information to the nearest neighbors 200 and 500.

  Of these nodes, only node 200 has been shown in FIG.

  The node 200 responds to the reception of the "Link_Test" information by the bus management node 100 with a confirmation,

  that is, a link test acknowledge "Link_Test_ACK".

  To achieve such confirmation, one can use the mechanisms

  s acknowledgment of the IEEE 1394 standard.

  The bus management node 100 also issued the "Link_Test" information with a transmission power reduced by 3 dB compared to the normal transmission power. Despite the reduced transmission power, the information "Link_Test" was correctly received by

  200. The correct reception of the "Link_Test" information is

  established by node 200 with normal transmission power, by the

  response to informafon "Link_Test" by acknowledgment (or confirmation

tion) "Link_Test_ACK".

  This "Link_Test_ACK" information of the nud 200 is written in the bus management node 100. This results for the bus management node 100 that the link between the bus management node 100 and the nud 200 in the bus management node 100. direction from the bus management node 100 to the node 200, is a link without disturbance or without significant deterioration. The node 200 also responds correspondingly to the information <. Link_Test "of n_ud 300 with confirmation s <Link_Test_ACK" which causes n_ud 200 to return to n_ud 300 with normal transmission power to confirm the correct reception of the "Link_Test" information sent by node 300 with a power of d emission reduced by 3 dB. It has thus been verified that the connection between the nodes 300 and 200 functions perfectly and that towards the node

o 300 to the number 200.

  The bus management node 100 responds correspondingly to the information at Link_Test of the node 200 with the confirmation "Link_Test_ACK" so that also the test of the light guide link between the nodes 200 and 100, in the direction from nud 200 to nud 100 has been successfully checked.For the Link_Test information from nud 200 to nud 100, nud 200 does not receive any feedback.

reply from nud 300.

  By issuing the "Link_Test" information, we launch a clock. If at the end of the clock time, the node concerned has not received a "Link_Test_ACK" confirmation for the "Link_Test" information sent, this "Link_Test" information is sent again by the corresponding node. In the example considered in FIG. 2, this means that, because of the first "Link_Test" information from node 200 to node 100, within the period defined by the clock, node 300 has not received no confirmation "Link_Test_ACK", then the node 200 sends again the information "Link_Test". This new issue of information "

  Link_Test "resets the clock.

  If, again, the node 200 does not receive a confirmation in the form of "Link_Test_ACK" within the period set by the clock, then the node 200 sends back to the bus management node a fault signal " Link_Test_Failed ". This fault signal contains as parameter the indication of the node concerned as well as the direction of the link between the nodes that led to this fault signal; in this case, it is the line of the light guide going in the direction of the node to the node 300. The corresponding parameter of the fault signal

  "Link_Test_Failed" is the following "Port_200_vers_300".

  For the transmission of the repeated information "Link_Test" by node 200 to node 300, after the first countdown of the clock, it is possible to record the transmission power to check whether, with a transmission power increased by compared to the reduced transmission power, and which remains always lower than the normal transmission power, there may have been a connection between the n_ud 300 and the n_ud 200. If this is the case, the information "Link_Test_Failed" is nevertheless transmitted by transmitting as another parameter, the transmission power taken step by step with

  transmission to the bus management node.

  o Figure 3 shows a corresponding flow chart. In step 30, the bus management node sends an automatic test command with the normal transmit power to all nodes in the network (see the "Link_Check_Mode" automatic test order in Figure 2). Receiving this automatic test order causes all nodes in the network to pass

in test mode.

  In step 31, each node Ki of the network sends to the directly neighbor nodes in the network topology and are nodes of the set M1, test information with a reduced transmission power with respect to the power of the network. emission in normal operation. The magnitude of the reduction of the transmit power with respect to normal operation can be contained as a parameter in the automatic test order of step 30 or be fixed in a predetermined manner. The transmission of the test information with a reduced transmission power 2s by the node Ki to the neighboring nodes of the set Mi in the step 31 can be done in series or in parallel; this means that the node Ki successively sends the test information to the different nodes of the set Mi or that the node Ki sends several test information essentially simultaneously to all the nodes of the set Mi. This step 31 is executed by all nodes Ko, Ki, Kn of the network. In step 32, the node Ki checks whether all the nodes in the set M have a confirmation of the receipt of the test information of step 31. If this is the case, it means that the links by the corresponding light guides are working properly and in step 33 there

there is no other action.

  If the control in step 32 on the contrary indicates that for one or more nodes of the set Mi, this can already be interpreted as a fault situation so that the node Ki sends a corresponding fault signal to the management nodes. of bus. However, in the embodiment of FIG. 3, the node Ki first checks, in

  step 34, if it is necessary to repeat the test information.

  For example, in the network it can be predetermined that there should be one or more repetitions of the test information broadcast before diagnosing a faulty link. If, for example, previously test information has already been sent to the nodes concerned of the set Mi from the node Ki, without the latter having received a confirmation, the control in the step 34 may show that it is not necessary to repeat the test information. Nud Ki then reports in

  step 36 a fault corresponding to the bus management node.

  If the control in step 34 shows the opposite, then the control information can be sent with a transmission power reduced, again, by the node Ki to the corresponding nodes of the set Mi to check whether the repetition of the control information results in a confirmation of receipt (see step 32). In the embodiment considered here, the reduced transmission power is first increased in step 35, according to a predetermined increase for

  o that it always remains below the normal transmission power.

  The test information is then sent again in step 31 by the node Ki to the concerned node (s) of the set Mi with a reduced transmission power, nevertheless increased to check again.

  in step 32 if a confirmation can be received.

  FIG. 4 shows an alternative embodiment of the method of the invention. In step 40, the bus management node sends test information to directly neighbor nodes in the network with reduced transmission power. The neighbors directly neighbors

  Bus management numbers are the nodes of the MB set.

  In step 41, the respective nodes of the set MB which have received the bus management node test information despite the reduced transmission power send a confirmation to the management node.

  of bus. This is done with normal transmit power.

  In step 42, the nodes of the set MB which have sent to the respectively neighbor nodes the test information received from the bus management node, i.e. neighboring nodes or each node of the bus node. set MB, send the test information to the nodes directly adjacent to the network. In step 43, these confirm to the nodes of the set MB that the neighboring nodes have, if any, received the test information and then transmit the test information to the other neighboring nodes thereof. etc. This distributes test information throughout the network. The confirmations issued by the different nodes of the network for the reception of the test information are recorded by the management node.

  of bus and are compared to the topology of the network in step 44.

  When all the planned confirmations have been recorded by the bus management node, this means that none of the light guide links has failed. In the opposite case, the bus management node generates, in step 45, a corresponding fault signal which is logged in a memory of the bus management node to generate, by way of

  example automatically, a service plan.

  The memory with the fault signal or with the service plan can be read during a maintenance operation to replace, as a precaution, the corresponding light guides. In addition, in step 45, the bus management node may issue an order to the

  n_uds for which there is no test information confirmation.

  In the corresponding nodes, the transmission power above the normal transmission power is then increased to compensate, for example, for greater damping of the light guide line. FIG. 5 shows another alternative embodiment of the process of FIG. 4. Step 50 corresponds to step 40 of FIG. 4. In step 51, the nodes of the set MB also send the confirmation with a reduced transmission power, that is to say that the reception of the confirmation in the bus management node, together with the connection by light guide towards the bus management node, are

  checked against neighboring nodes and are reset.

  Correspondingly, the nodes of the set MB see the test information to neighboring nodes in the slot 52, unlike step 42 of FIG. 3, but not to the nodes where the message is from. test information; in this case, it is not the bus management node. 3s In step 53, the test information is successively distributed throughout the network, similarly to step 43 of FIG. 4; the test information is again received by all neighboring nodes of the respective node, which have received the test information, except for the node from which the node concerned has received the test information.

  Steps 54 and 55 are carried out in a similar way to

pes 44 and 45 of Figure 4.

s

NOMENCLATURE

  1 Réscau 2 Light guide 3 Light guide 4 Light guide Light guide 6 Light guide lo 100 N_ud N_ud 300 N_ud 400 N_ud 500 N_ud 600 N_ud

Claims (19)

  1) Multi-node electronic system (100, 200, 300, 400, 500, 600) connected by light guides (2, 3, 4, 5, 6) to form a network characterized in that each node comprises: means for transmitting information with a reduced transmission power to each of its neighbor nodes; means for receiving a confirmation of the reception of the information by the neighbor node concerned; means for transmitting a signal of default to the management node   bus (100) in the absence of receipt a confirmation.   2) multi-node electronic system according to claim 1, characterized in that the network is formed as a serial bus system, preferably according to the   IEEE 1394, IEEE 1394a, IEEE 1394b standards.   3) Electronic multi-node system according to claim 1, for applications to motor vehicles including automotive electronics.   4) Multi-node electronic system according to claim 1, characterized in that   the network has a tree structure.   2s) multi-node electronic system according to claim 1, characterized in that the bus management node comprises means for issuing an automatic test command to the nodes of the network, so that the node transmission means are activated by receiving the automatic test order. 6) Multi-node electronic system according to claim 1, characterized in that   the bus management node comprises means for transmitting information   automatic test to each of its neighbor nodes and these   comprise means for transmitting the automatic test information   than. 7) multi-node electronic system according to claim 1, characterized in that each node comprises means for issuing the confirmation of the   receiving information to one of its neighbor nodes.   8) multi-node electronic system according to claim 7, characterized in that the means of transmitting the confirmation are made to issue the   confirmation with reduced transmission power.   9) multi-node electronic system according to claim 1, characterized in that the means for transmitting information in each of the nodes are made to repeat information transmissions from a predetermined duration, if within the predetermined duration, there was no   confirmation of receipt of information.    Multi-node electronic system according to claim 9, characterized in that the transmission means in the event of repetition of the transmission of the information   are designed to increase the transmission power step by step.   11) Multi-node electronic system according to claim 10, characterized in that   the means for emitting a fault signal are designed so that the signal   The fault code contains data indicating the magnitude of the reduced.   12) multi-node electronic system according to claim 1, characterized in that the means for transmitting information in each of the nodes are designed to transmit information with an increased transmission power in case a fault signal concerning the node and /or a   The link of the node concerned with another node of the network exists.   Multi-node electronic system according to claim 1, characterized in that   the bus management node has a memory for recording the   and the bus management node includes means for assigning a fault signal for a node and / or a link per line. in the network topology.   14) multi-node electronic system according to claim 13, characterized in that the bus management node comprises means for increasing the transmission power, means for transmitting information in one of the nodes. for which there is a fault signal, the means for increasing the transmission power being preferably achieved by means   to issue a corresponding order to the concerned nodes.    Multi-node electronic system according to claim 1, characterized in that   the bus management node has a memory for storing the fault codes.   16) multi-node electronic system according to claim 1, characterized in that it comprises means for generating a maintenance plan according to the or fault signals.   17) multi-node electronic system according to claim 1, characterized in that it comprises means for automatically activating the automatic test if the electronic system is in a state of low load or in the cut state. 18) Multi-node electronic system according to claim 17, characterized in that   the means for automatically launching an automatic test are carried out   to perform an automatic test when the ignition of the vehicle is cut. 19) A method of automatically testing an electronic system having several nodes connected by light guides to form a network characterized by the following steps: - information is transmitted at reduced power by each nodes to neighboring nodes, - confirmation of the reception of the information by the neighboring nodes concerned is issued each time the node which previously transmitted with reduced transmission power to a management node   bus in case there is no receipt of confirmation.    ) A method of automatically testing an electronic system having several nodes according to claim 19, characterized in that it initiates the automatic test by a test order   automatic bus management n_ud to all nodes in the network.   21) A method of automatically testing an electronic system having several nodes according to claim 19, characterized in that the automatic test is started by automatic test information from the bus management node to the neighbor nodes and each of the nodes. send your computer information to each other neighbors.   22) A method of automatically testing an electronic system having several nodes according to claim 19, characterized in that the transmission of the confirmation of receipt of the information is done with   : 5 reduced transmission power.   23) A method for automatically testing an electronic system having several nodes according to claim 19, characterized in that the transmission of the information with a reduced transmission power is confirmed by the node concerned if no confirmation is received. was received at   within a predetermined time.   24) A method of automatically testing an electronic system having several nodes according to claim 23, characterized in that the reduced transmission power is increased step by step during a repetition.   transmission of information.    ) A method of automatically testing an electronic system having a plurality of   Nodes according to Claim 19, characterized in that the transmission power of a node which has led to a fault signal is increased above the normal transmission power.   26) A method of automatically testing an electronic system having a plurality of   nodes according to claim 19, characterized in that   o the reduced transmission power which was made upon receipt of a confirmation   is part of the fault signal.   27) A method of automatically testing an electronic system having a plurality of   Nodes according to claim 19, characterized in that an automatic test is automatically initiated if the network is in a state of low load, preferably when the ignition of the vehicle is cut off.   28) Computer program including means for putting into practice   a method according to one of claims 19 to 27, the program being   executed by an electronic system, preferably the electronic system than a vehicle.