JPH10107821A - Multiplex transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To immediately shift to a sleep state by independently shifting to the sleep state by the establishment of the sleep conditions of a present node when even one of the plural nodes is turned to a communication impossible state. SOLUTION: The respective nodes 1 are the nodes for respectively controlling the locking/unlocking of a door and the ON/OFF of a light, etc., and respectively connected to a battery (B), a ground line (GND) and an ignition signal line (IG) in addition to a multiplex bus 4. The respective nodes are mainly composed of a CPU 2 for actually performing the processing of the nodes and a communication channel (communication control IC) 3 for performing the communication control in the case of performing communication with the other node in such a processing. Then, when at least one node among the plural nodes is in the communication impossible state, the respective nodes judge whether or not the prescribed sleep conditions of the present node are established and independently shift the present node to the sleep state when the conditions are established.

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,
The present invention relates to a multiplex transmission apparatus that performs a so-called sleep control when the entire apparatus is placed in a power saving state when a predetermined condition is satisfied.

[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 such a multiplex transmission device, sleep control is performed to stop power supply to a part of the device and save power consumption when there is no input / output from a control target for a predetermined time.

In general, in the sleep control of a multiplex transmission apparatus, after confirming that all nodes connected via a multiplex communication line can shift to a sleep state, all nodes simultaneously shift to a sleep state. It has become. This is because if each node shifts to the sleep state based on its own judgment, inconveniences such as a signal to be processed in communication between the nodes are not processed, which may cause a malfunction.

[0004] However, in order to confirm that all the nodes can shift to the sleep state, it is necessary to perform communication between the nodes. Therefore, if there is a node that has failed at this time, it is necessary to confirm it. , And cannot properly transition to the sleep state. As a solution to this, the node that has not responded to the communication to confirm whether it can enter the sleep state is judged to be in the failed state, and control is performed only by the other communicable nodes except that node. A method has been proposed in which a sleep condition is determined by using the method and the state is shifted to a sleep state (JP-A-6-38276).

[0005]

However, in the above method, the transition to the sleep state is determined based on the result of communication with the communicable node. A node in which only the communication control unit has failed, that is, a node that cannot communicate, cannot enter the sleep state. Thus, for example, if one node goes into such a state, the other nodes can ignore the failed node and transition to the sleep state appropriately, but the failed node returns power as usual. Will consume.

In the prior art, when a certain node fails, the other normal nodes take control and shift to the sleep state all at once. However, if any one of the nodes fails, it cannot be said that the entire device is in a normal state. Therefore, it is meaningless to take control of the entire device in such an abnormal state. Rather, in such a case, it is desirable that each node transition to the sleep state as soon as possible to prevent malfunction and reduce power consumption.

SUMMARY OF THE INVENTION In view of the above problems, the present invention can appropriately shift to a sleep state if a predetermined sleep condition is satisfied, even when not only the other node but also the own node cannot communicate. It is an object of the present invention to provide a multiplex transmission apparatus that performs sleep control when more than one of the nodes is unable to communicate, with a focus on saving power rather than controlling the entire apparatus.

[0008]

SUMMARY OF THE INVENTION A multiplex transmission apparatus according to the present invention includes a multiplex communication line and a plurality of nodes for exchanging signals via the communication line, and all nodes can enter a sleep state. A multiplex transmission apparatus in which all the nodes simultaneously shift to a sleep state at the time of, and when each of the plurality of nodes has at least one of the plurality of nodes in a communication disabled state, a predetermined sleep state of its own node. It is characterized by comprising sleep control means for judging whether or not a condition is satisfied and, when the condition is satisfied, causing the own node to shift to a sleep state alone.

Here, "at least one node" includes not only another node but also its own node. In other words, "when at least one node is in a communication disabled state"
This includes not only the case where communication with the node is not possible due to the occurrence of an abnormality in another node, but also the case where communication is not possible due to the occurrence of an abnormality in the communication control unit of the own node but continuation of other processing is possible. Meaning.

[0010] Further, as a method of "all the nodes simultaneously shift to the sleep state when all the nodes can shift to the sleep state", each node monitors the states of its own node and the other nodes, respectively. It is also possible to use a method of determining whether or not a node is in a state capable of transitioning to a sleep state, and transitioning to a sleep state when all nodes are in a state capable of transitioning to a sleep state. One of them is a sleep management node, and the sleep management node determines whether or not all nodes can shift to a sleep state when all nodes can communicate, and sleeps with another node when it becomes possible. It is desirable to use a method of instructing transition to the sleep state, and according to this instruction, all nodes including the sleep management node simultaneously transition to the sleep state. .

Further, each of the nodes includes a failure detecting means for detecting a failure of a communication IC included in the own node, and a mode switching means for shifting the node to a communication inhibition mode based on the failure detection by the failure detecting means. It may also have. In this case, it is desirable that the mode switching means is means for shifting the node to the communication inhibition mode when the failure of the communication IC is detected a predetermined number of times by the failure detection means.

Here, the "communication prohibition mode" means a state in which communication to be performed via a multiplex communication line is prohibited (stopped). In principle, the transition to the communication prohibition mode is performed when communication cannot be actually performed. However, depending on the method of setting the condition for shifting to the communication prohibition mode, the communication prohibition mode may remain in the communication prohibition mode even though the communication has actually been recovered. Therefore, in the case of the multiplex transmission apparatus in which the transition to the communication prohibited mode is performed, if the own node is not able to actually communicate in the “communicable state”, or is in the communication prohibited mode. Is defined.

The "predetermined number of times" may be one, but if it is two or more, the occurrence of an abnormality is confirmed many times, so that the abnormality is temporary and is recovered immediately. Does not shift to the communication prohibition mode, the difference between the state where communication is not actually possible and the communication prohibition mode is further reduced.

In the case where the multiplex transmission device is a device mounted on an automobile, the sleep control means includes:
When the ignition switch of the automobile is off and there is no input / output signal for a predetermined time, it is desirable to determine that the predetermined sleep condition of the own node is satisfied.

[0015]

According to the multiplex transmission apparatus of the present invention, if any one of a plurality of nodes becomes incapable of communicating, each node can operate independently of the state of the other nodes, regardless of the sleep condition of its own node. Since the transition to the sleep state by itself is established, the node in the non-communicable state can transition to the sleep state without knowing the state of the other nodes, and the other communicable nodes also become the non-communicable nodes. Irrespective of the existence of, and can immediately shift to the sleep state without spending time coordinating with other nodes.

[0016] One of the plurality of nodes may be a sleep management node. The sleep management node may determine whether each node can transition to a sleep state. If the node is instructed to shift to the sleep state, and all the nodes simultaneously shift to the sleep state in accordance with the instruction, the load of monitoring the status of the other nodes of each node can be reduced.

Further, each node detects a failure of the communication IC included in the own node, and shifts to the communication inhibition mode based on the detection, so that whether or not the own node can communicate is determined depending on the mode. It is possible to make a decision, and time for the decision can be saved. At this time, if the condition for shifting to the communication prohibition mode is that a failure has been detected a predetermined number of times, a more careful failure determination can be performed by increasing the predetermined number of times.

[0018]

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. It is assumed that they are connected to the multiplex bus 4, the battery (B), the ground line (GND), and the ignition signal line (IG) 10, respectively.

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. . In the following description,
The node being unable to communicate means that the CPU 2 has failed or that the CPU 2 is normal but the communication control IC cannot control communication due to a failure or a temporary abnormality. Further, since the failure detecting means and the mode switching means are actually processing programs executed by the CPU, in the following description, the respective means will be described as a series of processing performed by the CPU without particular distinction.

Generally, there are the following two forms of sleep control of such a multiplex communication apparatus. One is a mode in which one node has a function as a sleep management node as shown in FIG. 2, and the sleep management node determines whether or not a sleep condition of the entire apparatus is satisfied as necessary. The determination is made by communicating with the nodes, and when the condition is satisfied, all the nodes are instructed to shift to the sleep state. In general, the sleep management node often performs the same processing as the other nodes and further performs sleep management processing. However, the sleep management node may be independent as a sleep management dedicated node.

The other is, as shown in FIG. 3, in a form in which all nodes have an equal relation. Each node transmits a sleep frame to indicate that it is possible to shift to the sleep state. In addition to notifying the other nodes, receiving (confirming) the sleep frame transmitted by the other node to recognize each other's state, and shifting to the sleep state when it is determined that all nodes can shift to the sleep state. Is what you do.

Since the concept of the present invention does not depend on the above-described embodiment, it can be applied to any of the embodiments. However, as described above, the two embodiments are different in the method of determining the sleep condition and the like. Has the sleep management node of FIG. 2,
The processing is slightly different between the other nodes in FIG. 2 and the nodes in FIG. The following description is basically a common configuration and processing in the two modes, and processing different for each mode (type of node) will be described with that effect each time.

First, the configuration of each node will be described. 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) as shown in more detail in FIG.
/ F) circuit 6, an interface (I / F) circuit 9 for managing inputs and outputs from a control target such as a door lock, a watchdog circuit 7 for managing time and controlling an interrupt to a CPU, and a constant power supply circuit 8. The communication between the nodes is performed via the multiplex bus 4 connected to the bus I / F circuit 6.

FIG. 5 shows the configuration 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, and an area for classifying these is a frame type classification area (TYPE). The data frame is a frame for transmitting original control data. The check frame is a frame transmitted for the purpose of early detection of a failure of the own node or another node. The transmission of the check frame detects the failure / recovery of the communication control IC of the own node, and the other node checks the failure. By checking the frame, it is determined whether the node that transmitted the check frame is normal.

The sleep frame is a communication frame for sleep control, and is transmitted when the sleep management node instructs another node to shift to the sleep state in the form of FIG. 2, and is transmitted in each form of the node in FIG. Is transmitted when notifying the other node that the own node can shift to the sleep state. 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, sleep control processing, failure detection processing, and the like performed by the CPU of each node will be described in detail with reference to FIGS.

FIG. 6 is a flowchart showing the processing performed by the CPU when the power is turned on. First, a failure counter is initialized. The failure counter is incremented every time a failure is detected, and is referred to when determining the shift to the communication inhibition mode. Next, a failure diagnosis (initial check) of the communication logic circuit is performed. If an initial check error occurs due to the failure diagnosis, the communication logic circuit is soft-reset as a communication failure process, and the failure counter is counted up.

If the communication logic circuit is determined to be normal by the initial check, the CPU and the communication logic circuit are then initialized, and communication permission is set, that is, normal control is started. 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, a failure can be detected by timeout.

The check frame transmitted after the data frame increases the chance of detection by repeatedly transmitting a communication frame as described above,
It is for notifying its own state to other nodes, and plays a role as the failure detecting means.
Further, failure detection due to timeout also corresponds to the failure detection means.

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. 7. The predetermined processing is TWS control, specifically, door lock control, light control, and the like. 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 9 shown in FIG. In addition, IG ON in the main routine
Processing and sleep control processing are performed.

In the IG ON process, when the ignition switch (input from the ignition signal line 10) changes from OFF to ON, the communication inhibition mode is temporarily released, and
This is a process of diagnosing whether or not the communication control IC has recovered. Therefore, as shown in FIG. 8, it is first determined whether or not the ignition switch has changed from OFF to ON, and whether or not the communication switch is in the communication inhibition mode.
Initial setting of the communication logic circuit, setting of communication permission and clearing of the failure counter, that is, release of the communication inhibition mode are performed. The transmission of the data frame and the check frame performed thereafter is performed by the communication control I as described above.
This is a process for performing a re-diagnosis of C, but is transmitted even when the communication inhibition mode is not released as shown in the figure. This is for the purpose of early detection of the failure and recovery of the own node or another node as described above. The transmission processing of the data frame and the check frame is also performed as needed in other processing described below, and by performing such frequent frame transmission, early detection of failure and recovery is enabled. is there.

Here, prior to the description of the sleep control, other processes performed by the CPU will be described. During the processing of the main routine, for example, when 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. There are four types of interrupts from the communication logic circuit to the CPU:
There are a notification of communication control abnormality, a notification of completion of transmission of a communication frame previously transmitted, a notification of completion of reception of a communication frame from another node, and a notification of a change in the ANC table. 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, communication failure processing 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, and a failure counter is counted up. Here, when the failure counter becomes larger than a predetermined value,
The setting of communication inhibition, that is, the transition to the communication inhibition mode is performed. By increasing the predetermined value, it is possible to prevent the temporary transition to the communication inhibition mode due to a temporary abnormality. That is, as the predetermined value is larger, the shift to the communication control mode is performed more carefully. This value may be determined as a design item, and the value is not particularly limited.

In the above-described processing at the time of turning on the power, this processing is terminated only by a soft reset because it is determined that an error has occurred due to the determination of the next initial check error. However, in the case of calling from the communication control interrupt processing, Since this is not an initial check error, the initialization of the communication logic circuit and the setting of communication permission are performed, and the transmission processing of the data frame and the check frame is performed as the normal mode.

Next, processing for an interrupt other than the communication control abnormality notification will be described with reference to FIGS. 9 and 10 again. First, it is determined whether 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.

Here, as shown in the figure, when the received communication frame is a sleep frame, a sleep flag is set. When the multiplex communication apparatus is in the form shown in FIG. 2, this processing is performed in a node other than the sleep management node. Each node performs sleep control by referring to the sleep flag thereafter. On the other hand, when the multiplex communication apparatus has the configuration shown in FIG. 3, all the nodes set the sleep flag. In the embodiment of FIG. 3, it is assumed that there is one sleep flag for each node, the source of the sleep frame is identified (not shown), and the corresponding flag is set.

If it 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. This determination result is accumulated as other node information, and is referred to at the time of sleep control. 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.

The processing of the CPU in response to the interrupt from the communication logic circuit has been described above. Next, a failure detection and recovery detection process based on the 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 has been started (set). If it is not set, it means that there is no communication frame currently being transmitted, but the transmission timer is cleared because there is a possibility that the timer value of the previously transmitted transmission may remain.

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 did not complete even after 500 milliseconds, that is, some abnormality occurred. I do.

On the other hand, if the timer has not yet reached the time-out value, the system waits for the completion of transmission. At this time, a CS error (a state in which invalid data has occurred due to noise or the like) has not occurred. Check whether or not. 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 exceeds the timeout time, the CS error timer is cleared and communication failure processing is performed. When no CS error has occurred, only the CS error timer is cleared.

The detection of the failure and the recovery due to the timeout has been described above. However, the failure counter is counted up when the communication failure processing is called, and the failure exceeds the predetermined value. Is shifted to the communication prohibition mode.

Next, on the premise of the above processing, the sleep control processing will be described. As described with reference to FIG. 7, the sleep control process is a process called in the main routine. FIG. 13 is a flowchart showing sleep control processing of nodes other than the sleep management node in the embodiment of FIG.

First, the sleep flag set in the process of FIG. 9 is determined. If the sleep flag is 1, it means that a sleep state transition instruction has been received from the sleep management node, and the state transitions to the sleep state. When the sleep flag is not 1, the sleep flag cannot be received because the node is in the communication inhibition mode, the sleep management node has not issued a sleep state transition instruction, or the sleep management node is down. Three cases are conceivable.

Therefore, it is first determined whether or not the own node is in the communication prohibited mode. When the own node is in the communication prohibited mode, the sleep condition of the own node is determined without checking the state of the other node. If the own node is not in communication prohibition, it is determined whether the sleep management node is down. This is determined by referring to this information because the node down is determined in advance by receiving the check frame in FIG. 9 or changing the ANC table in FIG. As a result, if the sleep management node is normal, it means that the sleep condition of the entire apparatus has not simply been satisfied and it is not yet necessary to shift to sleep, so that normal control is continued. When the sleep management node is down (communication is not possible), the sleep condition of the own node is determined similarly to the case where the own node is prohibited from communicating.

Here, the sleep condition of the own node means that the ignition switch is off and there is no input / output from the control target (input / output of the interface circuit 9 in FIG. 5) for a predetermined time. If either one is not satisfied, the node returns to normal control because it should not transition to the sleep state. When both conditions are satisfied, the state shifts to the sleep state.

When shifting to the sleep state, first, the communication inhibition is set, and then the sleep setting is performed.
As a result, any communication is interrupted, and this state continues until a wake-up condition such as turning on an ignition switch is satisfied. When the wakeup condition is satisfied, the failure counter and the sleep flag are cleared, the communication prohibition mode is released (communication permission is set), and a data frame and a check frame are transmitted to notify another node of the state of the own node. You.

The processing of the nodes other than the sleep management node in the embodiment of FIG. 2 has been described above. Next, sleep control processing of the sleep management node in the same embodiment will be described with reference to FIG.

The sleep management node transmits a sleep frame when the sleep condition of the entire apparatus is satisfied in principle. First, it is determined whether or not its own sleep condition is satisfied. . This condition is
As in the case of 13, the ignition switch is off and there is no input / output from the control target for a predetermined time. If this condition is not satisfied, control returns to normal control. When the condition is satisfied (it is possible to sleep itself) and the communication is in the communication prohibition mode, processing to other nodes cannot be performed, so that the state immediately shifts to the sleep state. If the mode is not the communication inhibition mode, the status of another node is checked.

Checking the status of the other nodes is first checking whether the node is down and whether the sleep condition is satisfied. If any one of the other nodes is down and unreachable, it is no longer normal for the entire device, and immediately transmits a sleep flag without determining the sleep condition of the entire device,
The device itself shifts to the sleep state. If all the nodes are normal, the sleep condition of the entire device is determined. If the condition is satisfied, the state shifts to the sleep state. If not, the control returns to the normal control. The transition to the sleep state and the return processing when the wake-up condition is satisfied are the same as the processing in FIG.

Finally, the sleep control processing of each node in the embodiment of FIG. 3 will be described with reference to FIG. In this embodiment, first, it is determined whether or not the sleep condition of the own node is satisfied. This condition is, as in the case of FIG. 13, that the ignition switch is off and there is no input / output from the control target for a predetermined time. If the sleep condition is not satisfied, the process returns to the normal control. If this condition is satisfied, it is next determined whether or not the device itself is in the communication inhibition mode. In the communication prohibition mode, transmission to another node cannot be performed, so that the mode immediately shifts to the sleep state. If the communication node is not in the communication prohibition mode, a sleeve frame is transmitted to notify the other nodes that the own node can shift to the sleep state.

Next, it is confirmed whether or not there is a node that cannot communicate with other nodes. This is similar to the processing in FIG.
It is confirmed by referring to the information of the node down determination in the processing of FIG. Here, if at least one node is unable to communicate, the system immediately transitions to the sleep state. However, if all the other nodes are normal, it is determined whether or not the sleep flag of those nodes is 1. Will be
This flag is set in the processing of FIG. If all the sleep flags of the other nodes are set to 1, all nodes including the own node can shift to the sleep state, and the shift processing is performed. The shift processing and the return processing when the wake-up condition is satisfied are the same as the processing in FIG.

The sleep control processing of the three types of nodes has been described above. In any case, when at least one node has failed (including the failure of its own node)
Is the same in that, if the sleep condition of the own node is satisfied, the system shifts to the sleep state without taking overall control. This is the idea of the present invention.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating an embodiment of a multiplex transmission apparatus including a sleep management node.

FIG. 3 is a diagram illustrating a form of a multiplex transmission device without a sleep management node.

FIG. 4 is a diagram illustrating a configuration of a node of the multiplex transmission device according to an embodiment of the present invention.

FIG. 5 is a diagram illustrating a usage example of a communication frame.

FIG. 6 is a flowchart showing processing at power-on.

FIG. 7 is a flowchart showing a main routine.

FIG. 8 is a flowchart showing processing when an ignition switch is turned on.

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 sleep control processing of a node other than the sleep management node in the embodiment of FIG. 2;

FIG. 14 is a flowchart illustrating sleep control processing of a sleep management node in the embodiment of FIG. 2;

FIG. 15 is a diagram illustrating sleep control processing of each node in the embodiment of FIG. 3;

[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 10 ignition switch

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hitoshi Nakajima 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd.

Claims (5)

[Claims] 1. A communication system comprising: a multiplex communication line; and a plurality of nodes for exchanging signals via the communication line. When all nodes enter a state capable of shifting to a sleep state, all nodes simultaneously enter a sleep state. In the multiplex transmission apparatus to be shifted, each of the nodes is at least one of the plurality of nodes.
When one of the nodes is in a communication disabled state, it is determined whether a predetermined sleep condition of the own node is satisfied or not, and when the condition is satisfied, sleep control means is provided to cause the own node to shift to the sleep state alone. Multiplex transmission device. 2. One of the plurality of nodes is a sleep management node, and the sleep management node determines whether all nodes can shift to a sleep state when all nodes can communicate with each other, 2. The multiplex transmission apparatus according to claim 1, wherein when it becomes possible, another node is instructed to shift to a sleep state, and all nodes simultaneously shift to a sleep state according to the instruction. 3. Each of the nodes includes a failure detection unit that detects a failure of a communication IC included in the node, and a mode switching unit that shifts the node to a communication inhibition mode based on the failure detection by the failure detection unit. 3. The multiplex transmission device according to claim 1, further comprising: 4. The apparatus according to claim 3, wherein said mode switching means shifts the node to a communication inhibition mode when a failure of the communication IC is detected a predetermined number of times by the failure detection means. Multiplex transmission equipment. 5. The multiplex transmission device is a device mounted on an automobile, and the sleep control means, when an ignition switch of the automobile is off and there is no input / output signal for a predetermined time, the sleep control means of the own node. 5. The multiplex transmission device according to claim 1, wherein it is determined that a predetermined sleep condition is satisfied.