JPH10107805A - Multiplex transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To select a usual mode or a degradation mode in a proper timing by diagnosing the state of a communication control IC in real time in a multiplex transmitter provided with a plurality of nodes making signal communication via multiplex communication lines. SOLUTION: Each node transmits a prescribed frame repetitively to diagnose a state of a communication circuit 3 and stores a result of the diagnosis as, e.g. a count. When the state of the communication circuit 3 reaches a prescribed abnormality state (e.g. the count reaches a prescribed threshold or over), the mode is switched to the degeneration mode. Moreover, even after the degradation mode is selected, the state of the communication circuit 3 is diagnosed by repetitively trying the transmission of a prescribed frame and the diagnosed result is stored as a count similarly to the case with the abnormality detection, and when the state of the communication circuit 3 reaches a prescribed recovery state (e.g. the count reaches a prescribed threshold or below), the mode is restored to the usual mode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplex transmission apparatus for transmitting a signal through a multiplex communication line, and more particularly to a shift to degeneration control of each node when an abnormality occurs and a normal control of each node at the time of recovery. The present invention relates to a multiplex transmission device that performs a return process to a multiplex transmission device.

[0002]

2. Description of the Related Art In transmitting a signal for controlling electric components mounted on a vehicle, for example, an air conditioner, an audio device, and the like, a multiplex communication line is used in order to avoid enlargement and complexity of wiring. (Japanese Patent Laid-Open No. 61-2)
No. 24634).

In a multiplex transmission apparatus using such a multiplex communication line, when an abnormality occurs in a communication system in each connected node, each node shifts to degeneration control, and when each node recovers normally, There is also known a method of preventing a malfunction of the entire apparatus when an abnormality occurs by returning to the normal control (Japanese Patent Laid-Open No. Hei 4-304099).

[0004]

As described above, the degeneration control in the conventional multiplex transmission apparatus immediately shifts to the degeneration control when an abnormality is detected. However, there are two main types of abnormalities in the communication system: abnormalities that are unlikely to recover, such as failures in communication circuits, and abnormalities that have occurred temporarily and are likely to recover over time. . As an example of a temporary abnormality, when invalid data generated due to noise or the like is continuously detected for a predetermined time (CS
Error) and the like, but since such an abnormality may return to normal by initializing the communication IC, it is not always preferable to immediately shift to the degeneration control.

In the conventional multiplex transmission apparatus, the timing at which a node that has shifted to degeneration control can return to normal control has been limited. For example, in the case of an automobile, the re-diagnosis or initialization processing of the communication system is performed only when the battery is replaced and the power supply of each node is turned on, or when the so-called sleep control wakes up. However, it goes without saying that the battery is not changed frequently, and also in sleep control, the node in which the abnormality has occurred does not always transition to sleep mode normally, so there is always a wake-up timing. However, as a result, the node that has shifted to the degeneration control may not be recovered forever. This is not a problem when the generated abnormality is unlikely to be recovered, but is not preferable when the abnormality is expected to be recovered like the CS error.

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a multiplex transmission apparatus in which each node diagnoses a communication system more frequently, and shifts to degeneration control and returns to normal control at more accurate timing. It is intended to do so.

[0007]

SUMMARY OF THE INVENTION A multiplex transmission apparatus according to the present invention comprises a plurality of nodes for exchanging signals via a multiplex communication line, and a communication control I / O for performing communication control in the communication.
C; and a mode switching unit that diagnoses the state of the communication control IC and switches between the normal mode and the degenerate mode of the node based on the diagnosis result. The mode switching means
The state of the communication control IC is diagnosed by repeatedly transmitting a predetermined frame, and when the state of the communication control IC reaches a predetermined abnormal state, switching from the normal mode to the degeneration mode and switching to the degeneration mode are performed. After that, the state of the communication control IC is diagnosed by repeatedly transmitting a diagnostic frame, and when the state of the communication control IC reaches a predetermined recovery state, switching from the degenerate mode to the normal mode is performed. It is characterized by the following.

For example, when the node is in the normal mode, the mode switching means detects an abnormality of the communication control IC by transmitting the predetermined frame, and diagnoses a state of the communication control IC based on the abnormality detection. When the node is in the degenerate mode, recovery of the communication control IC is detected by transmitting the diagnostic frame,
It is preferable that the communication control IC diagnoses the state of the communication control IC based on the recovery detection.

[0009] The mode switching means, when the node is in the normal mode and the degenerate mode,
The transmission of the predetermined frame and the diagnostic frame performs abnormality detection and recovery detection of the communication control IC,
Based on the abnormality detection and the recovery detection, the communication control I
It is further desirable to be a means for diagnosing the state of C.

[0010] Specifically, the mode switching means holds, for example, the state of the communication control IC as a predetermined count value, and adds a predetermined value to the count value when the abnormality is detected. Means for subtracting a predetermined value from the count value at the time of detection, when the count value becomes equal to or more than a first threshold value, it is considered that the predetermined abnormal state has been reached, and the count value is determined by the first value. The predetermined recovery state may be considered to have been reached when the value falls below the second threshold after the value reaches the threshold.

In this case, it is preferable that the predetermined value to be added and / or subtracted is a value weighted according to the detected cause of abnormality and / or recovery.

[0012]

According to the multiplex transmission apparatus of the present invention, when each node detects an abnormality in the communication control IC, it does not immediately shift to the degenerate mode, but repeatedly transmits a predetermined frame to cause an abnormality. Communication control IC by detecting
When the state reaches a predetermined abnormal state, the mode shifts to the degeneration mode. Further, even after the shift to the degenerate mode, the transmission of the predetermined diagnostic frame is repeatedly attempted so that the communication control I
When the recovery of C is detected and the communication control IC reaches a predetermined recovery state, the mode shifts to the normal mode. As a result, if the detected abnormality is temporary and recovers immediately,
Normal control can be continued without shifting to degeneration control,
Further, even when the mode shifts to the degeneration control due to the detection of a temporary abnormality, the communication control IC is repeatedly operated by repeatedly transmitting the predetermined diagnostic frame as described above.
As soon as the cause is removed, the recovery can be detected and the normal mode can be entered.

Further, in the normal mode, not only abnormality detection but also recovery detection is performed, and by diagnosing the state of the communication control IC based on the detection of the abnormality and the recovery, more accurate diagnosis can be performed. Similarly, even in the degenerate mode, more accurate diagnosis can be performed by performing abnormality detection as well as recovery detection.

The state of the communication control IC is held as a predetermined count value, and a predetermined value is added to the count value when abnormality is detected, and a predetermined value is subtracted from the count value when recovery is detected. With this configuration, when the count value becomes equal to or more than the first threshold value, the mode shifts to the degenerate mode, and when the count value becomes equal to or less than the second threshold value, the mode shifts to the normal mode. The device can be simplified. At this time, if the value added to the count value or the value subtracted from the count value is a value weighted according to the cause of the abnormality or the recovery, a more accurate diagnosis can be performed.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an outline of a configuration of a multiplex transmission apparatus according to an embodiment of the present invention. Since the present embodiment is a multiplex transmission device mounted on an automobile, each node 1 shown in the figure is a node that controls, for example, opening and closing a door, locking / unlocking a door, turning on / off a light, and the like. And connected to the battery (B), the ground line (GND), and the ignition signal line (IG) in addition to the multiplex bus 4.

Each node 1 mainly includes a CPU 2 for actually performing the processing of the node, and a communication circuit (communication control IC) 3 for controlling communication when communicating with another node in such processing. . The degeneration control described below relates to a process performed when an abnormality occurs in the communication control IC 3, and it is assumed that the CPU 2 is normal. Since the mode switching means is actually a processing program executed by the CPU, the following description will be made as processing performed by the CPU.

Next, the state transition of each node will be described with reference to FIG. As shown in FIG. 2, in the present embodiment, each node transitions between three states: a normal mode, a degenerate mode, and a prohibited mode. The normal mode means a normal state, and a node in the normal mode performs control that should be performed by the node, that is, controls input / output signals from a control target. The prohibition mode means a state in which, for example, the communication control IC has failed and there is no prospect of recovery. In this case, all control is prohibited (stopped). However, at a timing when the failure may be recovered, such as when the power is turned on, the prohibition mode is temporarily released, and the normal mode is set. In this case, if the failure has not recovered, immediately after the start of the processing, the condition for shifting to the inhibition mode is satisfied again,
It becomes the prohibition mode. The degeneration mode refers to a state in which control to be performed is temporarily suspended. It should be noted that the prohibition mode may be considered as a kind of the degeneration mode, and the control may be performed by transition between the two states.

The present invention relates to the processing of each node in the reduced mode and the transition from the normal mode to the reduced mode or the return from the reduced mode to the normal mode. Therefore, the basic concept of these processes will be described next.

In this embodiment, as shown in FIG. 2, the value of a predetermined counter is updated, and each mode is switched by referring to the updated value. This counter is incremented according to the type of abnormality that has occurred in the communication circuit and the number of detections. For example, if the transmission cannot be completed for a certain period of time, the value 5 is added, and a CS error is generated for a predetermined period of time. In the subsequent case, the value of the counter is increased as the probability of recovery from the detected abnormality is reduced and the number of times of detection is increased, such that the value 1 is added. Similarly, this counter decrements the value 1 when it is detected that the communication circuit has recovered normally. As a result, when the abnormality detected in the normal mode is temporary, and when the abnormality returns immediately, the count value stops increasing and the condition for shifting to the degeneration mode is not reached.

FIG. 3 is a diagram showing abnormality detection in the normal mode and transition to the degeneration mode based on the abnormality detection. In the normal mode, each node (CPU) repeatedly transmits a diagnostic frame in addition to the original control data frame. At this time, the transmission interval may be constant or irregular. Generally, the CPU detects an abnormality in the communication circuit by interruption from the communication circuit or by detecting a timeout with a transmission timer.
Therefore, by repeatedly performing the transmission as described above, the chances of abnormality detection are increased, and the abnormality can be detected at an early timing. Such transmission is repeated even after the first abnormality is detected, and a predetermined value is added to the counter every time an abnormality is detected.

FIG. 4 is a diagram showing a method of detecting recovery in the degenerate mode. After the transition to the degenerate mode, transmission of control data frames is interrupted.
Only the transmission of the diagnostic frame is continued. This allows
When the abnormality is recovered, the recovery can be detected when the transmission of the diagnostic frame is completed normally. In other words, not only when normal control is performed in the normal mode, but also by repeating transmission of some frame at all times, abnormality and recovery can be detected in real time, and transition to the appropriate mode at the appropriate timing is possible. It becomes possible.

The outline has been described above. Next, the configuration and operation of each node in this embodiment will be described.
This will be described in more detail. Each node 1 shown in FIG. 1 includes a CPU 2, a communication logic circuit 5 corresponding to the communication control IC 3 and a bus interface (bus I / F) circuit 6, such as a door lock, as shown in FIG. Interface (I) that manages input and output from the
/ F) a circuit 9, a watchdog circuit 7 for performing time management and controlling interrupts to the CPU, and a constant power supply circuit 8. Communication between nodes is performed by the multiplex bus 4 connected to the bus I / F circuit 6. Done through.

FIG. 6 shows the structure of a communication frame communicated via the multiplex bus 4. Like a general communication frame, this communication frame is separated by an SOF indicating the start of the frame and an EOF indicating the end of the frame, and has a priority area (P) for controlling the priority in the event of a frame conflict.
RI) and a reception response area (ANC) for confirming reception of a communication partner. Further, frame error correction is performed by a cyclic coding (CRC), and a data check (CRC) area is prepared as an area for this.

In the present embodiment, there are three types of communication frames, namely, a check frame, a data frame, and a sleep frame. An area for classifying these is a frame type classification area (TYPE). Here, the check frame is equivalent to the above-mentioned diagnostic frame and is transmitted for the purpose of detecting abnormality / recovery of the communication control IC. The other node can also check the check frame to determine whether the node that has transmitted the check frame is normal or not.
The data frame is a frame for transmitting original control data. The sleep frame is for performing so-called sleep control for power saving, but is not a requirement of the present invention, and thus detailed description is omitted here. In the present embodiment, only the sleep frame is a different type, and the other two types of frames are classified as the same type.

As another area, a data function classification area (ID) is prepared to represent the meaning of the frame (for example, for door lock control). Needless to say, the data area (DATA) is an area for storing data which is the original purpose of frame communication.

Next, IC diagnostic processing and mode switching processing performed by the CPU of each node, specifically, transmission and reception of each frame, updating of the counter, transition to the degenerate mode based on them, and return to the normal mode Will be described in detail with reference to FIGS. Here, as shown in FIG. 2, it is assumed that the mode shifts from the normal mode to the degeneration mode when the count value exceeds 30, and to the prohibition mode when the count value exceeds 100.

FIG. 7 is a flowchart showing the processing performed by the CPU when the power is turned on. When the power is turned on, the counters are all initialized to zero. Here, in the present embodiment, the counters F1 to F4 are selectively used depending on the cause of the failure, but it goes without saying that the counters F1 to F4 may be realized by one counter.

After the counter is initialized, a failure diagnosis (initial check) of the communication logic circuit is performed. If an initial check error has occurred due to this failure diagnosis, a value 100 is set in the counter F1. As described above, the value of 100 is a value that satisfies the condition for shifting to the prohibition mode. Therefore, here the counter F
By setting 1 to 100, subsequent communication by the communication control IC is prohibited. After the setting of the counter F1, a soft reset of the communication logic circuit is performed as a communication failure process.

If it is determined by the initial check that the communication logic circuit is normal, the CPU and the communication logic circuit are then initialized, communication permission setting, that is, control as a normal mode is started, and initial transmission is performed. As a process, first, a data frame is transmitted, and then a check frame is transmitted. When the communication inhibition mode has been set, the communication inhibition mode is canceled by the setting of the communication permission when the power is turned on.

Regarding the transmission of these frames, a transmission timer is set in each case, and if the transmission is not completed within a predetermined time due to some abnormality, an abnormality can be detected by timeout.

The purpose of transmitting the check frame following the data frame is to increase the chances of detection by repeatedly transmitting the communication frame as described above, and to notify other nodes of their own status. is there.

When the above processing is completed, the processing returns to the main routine. Here, the main routine means performing predetermined processing cyclically as shown in FIG. 8, but the predetermined processing is TWS control, specifically, control of door lock and light control. Warning processing for forgetting to turn off. That is, it means the original input / output processing to be performed by the CPU via the interface circuit shown in FIG. In addition, sleep control is also performed, but the description is omitted here.

During the processing of the main routine, for example, if there is any input from the multiplex bus, an interrupt to the CPU is generated from the communication logic circuit. FIG. 9 and FIG. 10 show this communication control interrupt processing, that is, the processing performed by the CPU when interrupted from the communication logic circuit. The interrupts from the communication logic circuit to the CPU include the following four types: notification of communication control abnormality, notification of completion of transmission of a communication frame that has been transmitted previously, and completion of reception of a communication frame from another node. Notification, and ANC
There is a notification that the table has changed. The CPU determines which of the four interrupts is in the above-described order, and performs the corresponding processing.

First, in the case of notification of communication control abnormality, a value of 10 is added to the counter F4, and a communication failure process is performed. The communication failure process is a process as shown in FIG. 11. First, a soft reset of the communication logic circuit is performed. In the above-described processing at the time of power-on, the processing is terminated only by a soft reset because it is determined that an error has occurred due to the determination of an initial check error. However, in the case of a call from the communication control interrupt processing, an initial check error is generated. Therefore, after that, the initial setting of the communication logic circuit and the setting of the communication permission are performed, and the transmission processing of the data frame and the check frame is performed as the normal mode.

Next, the processing for an interrupt other than the communication control abnormality notification will be described with reference to FIGS. 9 and 10 again. The occurrence of an interrupt other than the communication control abnormality means that the communication itself is normally performed.
In this case, as shown in FIG.
A determination is made as to whether it is greater than, and if it is greater, the value 1 is subtracted. If not greater than 0, the counter F
4 remains unchanged.

Here, when the counter F4 is larger than 0,
That is, it means that an interruption has occurred in the past due to a communication control abnormality. In other words, if a communication control abnormality has occurred in the past, the fact that the communication is currently performed normally means that the communication logic circuit has been recovered, so in order to hold the recovery as information, The counter F4 is counted down. On the other hand, if a communication control abnormality has not occurred in the past, the fact that communication is normally performed at present has no particular meaning, so that the counter is left as it is.

Then, it is first determined whether or not the notification is a transmission completion notification. If the notification is a transmission completion notification, a transmission timer stop process is performed. Next, it is determined whether or not the reception completion notification is received. If the reception completion notification is received, it is determined whether the received communication frame is a check frame, a data frame, or a sleep frame, and the determination is performed on each frame. Is performed.

If the notification is not a reception completion notification, it is determined whether or not the interruption is due to a change in the ANC table. Here, the ANC table means bits in the ANC area of the communication frame. As described with reference to FIG. 6, the ANC table records a response when the communication frame transmission destination normally receives the communication frame. It is an area for doing. Therefore, the state of the other node can be determined based on a change in the ANC table. Also here, a data frame and a check frame are transmitted, and the status is notified to the other nodes. In particular, if the recovery of the downed node is detected by a change in the ANC table, the frame transmitted here has the purpose of providing the latest information to the node.

In the above, the processing of the CPU in response to the interruption from the communication logic circuit has been described, and the addition and subtraction of the counter when the abnormality or the recovery of the communication logic circuit is detected in the process has been described. Next, abnormality detection and recovery detection processing due to timeout of the transmission timer will be described.

As described above, when transmitting a communication frame such as a data frame, a transmission timer is set simultaneously with the transmission. In the present embodiment, the timeout time is 500 milliseconds. This transmission timer is checked at predetermined intervals. FIG. 12 shows a communication failure detection process by this timer.

This process is started periodically by the CPU at a predetermined cycle. First, it is determined whether or not the transmission timer is set. If it is not set, there is no communication frame currently being transmitted. In this case, if the transmission timer is a value other than 0 (0 <transmission timer <500 ms), That is, the previous transmission did not time out,
Means successful. Therefore, as in the case of the above-described interrupt processing, if the counter F2 is greater than 0 (if an abnormality has been detected in the past), the value of the counter becomes 1
(The recovery of the communication logic circuit is left as a counter value), and if the counter value is 0, nothing is performed. After this,
The transmission timer is cleared regardless of the value of the counter F2.

On the other hand, if the timer is set, the CPU increments the timer counter,
It is determined whether or not the timer has exceeded 500 milliseconds, that is, whether or not a timeout value has been exceeded. If the timer exceeds 500 milliseconds, it means that the transmission has not been completed after 500 milliseconds, that is, some abnormality has occurred, so the counter F2 is cleared after clearing the transmission timer. Then, the communication fault processing is performed by adding the value 5.

On the other hand, if the timer has not yet reached the time-out value, it will continue to wait for transmission completion. At this time, it is checked whether a CS error has occurred. If a CS error has occurred, the CS error timer detects whether or not the state has continued for a predetermined time. The timeout time in this case is also set to 500 milliseconds. If the timer has exceeded the timeout period, the CS error timer is cleared, the value 1 is added to the counter F3, and a communication failure process is performed. When no CS error has occurred, the timer is cleared, and if the counter F3 is larger than 0, the value 1 is subtracted. This is because, when a CS error is detected in the past, the fact that the error state has been recovered is held as information by subtracting a counter, as in the case of the above-described interrupt processing.

The detection of the abnormality and the recovery due to the timeout has been described above. Next, a mode switching process will be described with reference to the counter updated in the timeout process and the above-described interrupt process.

The cyclic transmission process of FIG. 13 is a process that is periodically started at predetermined intervals, like the communication failure process of FIG. 12, and switches the mode according to the value of the counter.
This is a process for cyclically transmitting a communication frame according to the mode. In the case of the prohibition mode, the transmission process is prohibited, so this process is not called. Therefore, when this process is performed, the node must be in the normal mode or the degenerate mode. become.

First, four counters, ie, a counter F1 (FIG. 7) set in the processing at the time of power-on, a counter F2 (FIG. 12) when a timeout is detected, and C
The count values of the counter F3 (FIG. 12) indicating the S error and the counter F4 (FIG. 9) indicating the abnormality of the communication control are added up, and the total count value F is obtained. If the node is not in degraded mode,
That is, in the case of the normal mode, first, the total count value F
It is determined whether or not satisfies the condition for shifting to the prohibition mode, that is, whether or not exceeds 100. If the number exceeds 100, communication prohibition is set, and this node enters the prohibition mode. If it does not exceed 100, it is determined that the condition for shifting to the degeneration mode is satisfied, that is, 3
It is determined whether or not the value exceeds 0. If the value exceeds 0, switching to the degenerate mode is performed. If not, control processing in the normal mode is performed as it is.

On the other hand, if the node is in the degenerate mode, it is determined whether the condition for returning to the normal mode is satisfied, that is, whether the total count value F is 0 or not. Shifts to the normal mode. When F is other than 0, the processing in the degeneration mode is performed as it is. Here, the process in the degenerate mode is a process in which only a check frame is transmitted without performing communication of an original control communication frame such as a data frame, as described above.

Next, the normal mode, that is, the state of frame transmission in a normal state, and the transition from the normal mode to the degeneration mode and the inhibition mode will be described with reference to FIGS. FIG. 14 is a diagram showing a state of frame transmission of three nodes in a normal state. An upward arrow at the bottom of the figure indicates an event that occurs from a point at which a driver opens a door to get into a car to a time when driving is completed. FIG.

Each node that was initially in the sleep state is woken up by a door SWON signal generated by opening the door, performs initial transmission, and then transmits a data frame for performing control according to the door SW ON. I do. Similarly, a frame is transmitted in response to an event such as a door SW OFF or an IG key ON. What should be noted here is that instead of sending one frame in response to an event and ending it, the IG key is turned off, that is, a cyclic data frame or check is always performed as long as the normal state is maintained until the operation ends. This means that a frame is being transmitted. Thereby, abnormality can be detected earlier.

Next, FIG. 15 shows a case where the mode shifts from the normal mode to the degeneration mode. As in the case of FIG. 14, the node in the sleep state is woken up by the door SW ON, and the initial transmission is performed first.
In the example of FIG. 15, this initial transmission is not
It is assumed that a timeout has been detected in the communication failure processing of 12. In this case, the data frame is retransmitted after the initialization of the communication logic circuit is reset in the communication failure processing of FIG. 11, and when the timeout occurs, the retransmission is further repeated. Here, by detecting one timeout,
The counter F3 is counted up by five. Since the condition for shifting to the degenerate mode is that the count value exceeds 30, if the failure of the initial transmission is repeated six times, the counter F3 reaches 30, thereby switching from the normal mode to the degenerate mode. . In the degenerate mode, only check frame transmission is performed. In the example of FIG. 15, it is assumed that the communication logic circuit recovers almost at the same time as the transition to the degeneration mode. In this case, since the transmission of the check frame is normally completed, the counter F3 is counted down by one each time the transmission of the check frame is completed. Thus, if the check frame is transmitted 30 times, the value of the counter F3 becomes 0, and the mode returns from the degenerate mode to the normal mode.

Finally, the transition from the normal mode to the prohibition mode will be described with reference to FIG. The example illustrated in FIG. 16 illustrates a case in which a communication control abnormality has occurred in the initial transmission due to a failure of the communication logic circuit, and the abnormality has been detected as a communication control abnormality in the communication control interrupt processing in FIG. 9. is there. In this case, the value 10 is added to the counter as shown in the flowchart of FIG. If the failure of the communication logic circuit is fatal and cannot be recovered, the counter is incremented by 10 each time the initial transmission is repeated. When the counter reaches 30, the mode is switched to the degeneration mode and the transmitted frame is only a check frame. Since the communication logic circuit does not recover, the counter value is further counted up even in the degenerate mode. When the counter value finally reaches 100, the mode is switched to the inhibition mode, and the transmission of a communication frame is not performed thereafter.

As described above, one embodiment of the present invention has been described in detail. The feature of the present invention resides in that an abnormality or recovery is quickly detected by repeatedly transmitting a predetermined communication frame. In the form,
The configuration of the communication frame, the type of abnormality to be detected, the degree of weighting for the cause of the abnormality (counter value to be added), and the like are merely examples.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a multiplex transmission apparatus.

FIG. 2 is a diagram showing a state transition of each node.

FIG. 3 is a diagram showing an abnormality detection in a normal mode and a transition to a degeneration mode.

FIG. 4 is a diagram showing detection of recovery in a degenerate mode and return to a normal mode.

FIG. 5 is a diagram illustrating a configuration of a node of the multiplex transmission device according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating a usage example of a communication frame.

FIG. 7 is a flowchart showing processing at power-on.

FIG. 8 is a flowchart showing a main routine.

FIG. 9 is a flowchart showing communication control interrupt processing;

FIG. 10 is a flowchart showing a communication control interrupting process subsequent to FIG. 9;

FIG. 11 is a flowchart showing communication failure processing;

FIG. 12 is a flowchart illustrating a communication failure detection process.

FIG. 13 is a flowchart illustrating a cyclic transmission process.

FIG. 14 is a diagram illustrating a frame transmission state of each node in a normal mode.

FIG. 15 is a diagram showing a transition from the normal mode to the reduced mode and a return from the reduced mode to the normal mode.

FIG. 16 is a diagram showing a transition from a normal mode to a prohibited mode.

[Explanation of symbols]

 1 node 2 CPU 3 communication circuit 4 multiplex bus 5 communication logic circuit 6 bus interface circuit 7 watchdog circuit 8 constant power supply circuit 9 interface circuit

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Toshifumi Ikeda 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd.

Claims (5)

[Claims] 1. A plurality of nodes for exchanging signals via a multiplex communication line, a communication control IC for performing communication control in the communication, and diagnosing a state of the communication control IC. A multiplex transmission apparatus including a plurality of nodes each having a mode switching unit for switching between a normal mode and a degenerate mode of the node based on the communication control IC by repeatedly transmitting a predetermined frame. Diagnosing the state, and when the state of the communication control IC reaches a predetermined abnormal state, switching from the normal mode to the degenerate mode is performed, and after switching to the degenerate mode, transmission of the diagnostic frame is repeated. Diagnoses the state of the communication control IC, and switches from the degraded mode to the normal mode when the state of the communication control IC reaches a predetermined recovery state. Multiplex transmission apparatus and performs. 2. The mode switching means detects an abnormality of the communication control IC by transmitting the predetermined frame when the node is in the normal mode, and diagnoses a state of the communication control IC based on the abnormality detection. When the node is in the degenerate mode, the communication control IC detects recovery by transmitting the diagnostic frame, and diagnoses the state of the communication control IC based on the recovery detection. The multiplex transmission apparatus according to claim 1, 3. The mode switching means performs an abnormality detection and a recovery detection of the communication control IC by transmitting the predetermined frame and the diagnostic frame when the node is in the normal mode and the degenerate mode, 3. The multiplex transmission apparatus according to claim 1, further comprising means for diagnosing a state of the communication control IC based on the abnormality detection and the recovery detection. 4. The communication control device according to claim 1, wherein
Means for holding a state of C as a predetermined count value, adding a predetermined value to the count value when the abnormality is detected, and subtracting a predetermined value from the count value when the recovery is detected, Considering that the predetermined abnormal state has been reached when the count value is equal to or greater than the first threshold,
After the count value becomes equal to or more than the first threshold value, the second
4. The multiplex transmission apparatus according to claim 1, wherein the predetermined recovery state is considered to have been reached when the threshold value has become equal to or less than the threshold value. 5. The multiplex transmission apparatus according to claim 4, wherein said predetermined value to be added and / or subtracted is a value weighted by a detected cause of abnormality and / or recovery.