JP3401355B2 - Multiplex transmission equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplex transmission device for exchanging data with each other via a common multiplex transmission line, and particularly to reducing the amount of data traffic on the multiplex transmission line of data transmitted at a constant cycle. The present invention relates to a multiplex transmission device.

[0002]

2. Description of the Related Art In recent years, in order to eliminate the enlargement and complication of wiring (wiring harness) connecting electric component units with the increase in the number of electronic parts (electric component units) of automobiles, communication provided in a plurality of electric component units. Attention has been paid to the multiplex communication in which the communication node is connected to a common multiplex communication line, and the signal transmission between the electrical units is performed by the communication node. This multiplex communication is to transmit a plurality of data on one wiring by time division multiplexing, and basically takes the form of serial transmission.

The communication node used for such multiplex communication is connected with signal generating parts such as various sensors and switches as an electrical unit and various operating parts such as various actuators and motors provided in various parts of the vehicle. There is. Then, each communication node generates control information called a communication frame based on the detection signals from the various connected signal generators, and sends this communication frame through a multiplex communication line, or another node. It takes in the communication frame sent from and controls the electrical unit. Further, the types of frames generated by the communication node are mainly periodic control information for sending detection values of a sensor or the like in a fixed cycle, and non-periodic non-periodic information regarding ON / OFF operations of switches and the like. It is roughly divided into control information.

FIG. 1 shows a data format of a communication frame adopted in a conventional automobile multiplex transmission device. In FIG. 1, frame F is SD (Start Deli
miter) code, priority code, frame ID
The frame structure has a code, a data length, data 1 to data N, and a check code.

First, the "SD code" is a specific code indicating the start of the frame F, and the receiving multiplex node uses this S code.
When the D code code is received, the start of the frame F is recognized. The “priority code” is a code indicating a priority order that indicates which signal should be preferentially processed when a plurality of multiple nodes transmit data at the same time and the signals collide. In this embodiment, the lower the bit value, the higher the priority is assigned. This is because the low level is WIRED-OR in the bus 1. If signals are sent from multiple nodes at the same time, the "priority code" of the node with the higher priority remains on the bus 1, so that the lower node has a different "priority code" from its own. Since it has changed to, a collision is detected. Then, by delaying the retransmission of its own failed frame, the retransmission from the node with a high priority is prioritized.

The "frame ID code" is a code indicating the destination of the frame and corresponds to so-called functional addressing. This ID code is attached to the node of the transmission source. The number of data following this is written in the "data length", and if there are N data, N is sent as the data length. The multi-node which receives this frame reads the data of the data length. And the field following the data is CR
By confirming this with the C check code (error detection code), it is possible to know the end of the frame.

The ACK field is where ACK signals from other nodes (N nodes are planned for the entire system) are inserted. In addition, in conventional multiplex communication, two types of multiplex communication lines are used. One that can communicate by turning on the ignition switch (referred to as a high-speed transmission line for convenience) and one that is connected to a battery power source and can always communicate. (Referred to as a low-speed transmission line for convenience). Of the communication nodes connected to these two types of multiplex communication lines, the communication node connected to the high-speed transmission line is the communication node that controls engine control and ABS control, and the CPU processing speed and memory capacity. Is set to a large value. On the other hand, the communication node connected to the low-speed transmission line is a communication node that controls the operation of the wiper and various lamps, and the calculation processing speed and memory capacity of the CPU are set low, and in some cases, the CPU is not mounted. In some cases, communication frames are transmitted and received via a communication IC.

However, in the above high-speed and low-speed transmission lines, since a plurality of communication nodes are commonly connected, the periodic control information from the sensor and the like and the aperiodic control information from the switches are common. There is a mixed state in the multiplex communication line, and when one of the information is transmitted, the other information may adversely affect the information being transmitted.

In order to solve such a problem, in the prior art disclosed in Japanese Patent Laid-Open No. 6-169313, a periodic information communication line and an aperiodic information communication line are separately provided, and the periodic information communication line is provided. Multiple nodes that send or receive periodic control information are connected, and multiple nodes that send or receive aperiodic control information are connected to the aperiodic information communication line. Transfer of each control information is performed on both communication lines. It has been proposed to selectively perform at a predetermined communication node connected to.

[0010]

However, in the conventional multiplex transmission apparatus as described above, the periodic control information is
Since the control information to be sent this time is almost the same as the control information of the previous time, unnecessary control information is sent to the multiplex communication line at regular intervals because it is sent at a constant cycle based on the detection signal of the sensor etc. As a result, the amount of information is increased, and especially the ROM / RAM capacity of the communication node with a low memory capacity connected to the low-speed transmission line becomes insufficient, or the load related to arithmetic processing increases and the actuator increases. However, there is an inconvenience that an operation delay occurs.

Therefore, the present invention has been proposed to solve the above-mentioned problems of the prior art. The object of the present invention is to reduce the traffic amount of the bus and to reduce the R of the communication node.
An object of the present invention is to propose a multiplex transmission device that prevents the occurrence of operation delay of actuators and the like by reducing the CPU load due to an increase in OM / RAM capacity and the like.

[0012]

[Means for Solving the Problems] and

In order to solve the above problems and achieve the object, the multiplex transmission apparatus of the present invention has the following configuration. That is, high
The first communication node connected to the high speed communication line and the low speed communication node.
In the multiplex transmission apparatus and a second communication node connected to the signal line, the second communication node includes means for detecting whether a predetermined event has occurred, when the predetermined event occurs , comprising means for calculating a change amount of event data based on the predetermined event, when the change amount of the event data does not exceed a predetermined value, and means for inhibiting the transmission of the communication frame with the event data , The first communication node
Is more volatile than the second communication node.
Send and receive event data .

Further, the multiplex transmission device of the present invention is capable of high-speed communication.
The first communication node connected to the communication line and the low-speed communication line
To a multiplex transmission device having a second communication node connected thereto
At the second communication node, a predetermined event occurs.
And a means for detecting whether or not the predetermined event has occurred.
In this case, the change amount of event data based on the predetermined event is calculated
And the amount of change in the event data does not exceed a predetermined value.
If it does not, the transmission of the communication frame containing the event data is prohibited.
Stopping means, wherein the second communication node is
The memory capacity is set smaller than that of the first communication node.
Or the CPU processing speed is set low.
It is Also, preferably, the high-speed communication line is
Communication is possible when the ignition switch is turned on
And the low speed communication line is connected to the vehicle battery power supply.
The communication is always possible .

As described above, the communication node does not transmit the event data when the change amount of the event data detected by the sensor or the like does not exceed the predetermined value, so that the traffic volume of the bus is reduced. By reducing the CPU load due to an increase in the ROM / RAM capacity of the communication node, it is possible to prevent the operation delay of the actuator and the like from occurring.

[0015]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. The multiplex transmission device of the embodiment described below is a so-called CSMA (Carrier Sense Multipl
This is an example applied to a network access method of eAccess) / CD (Collision Detection) method.

(Circuit Configuration of Communication Node) FIG. 2 is a diagram showing a detailed configuration of a communication node used in the multiplex transmission network of the vehicle of this embodiment. In the present embodiment, a communication node (hereinafter referred to as a basic node) in which a CPU and a communication IC are integrated and incorporated, a CPU and a communication IC
Communication node (hereinafter referred to as a high-basic node) that is built in as a separate IC, and a communication node that does not have a CPU and has only an I / O function (hereinafter referred to as a stand-alone node)
The three types of nodes are used as communication nodes.

The stand-alone node can perform communication control and simple input / output of data that do not require high-level data processing such as a node that controls a switch and an indicator lamp indicating that the switch is turned on. . Next, in order to clarify the difference between the basic node (communication node with a built-in CPU) and the high basic node, the circuit configuration of the high basic node will be described. The communication node shown in FIG. 2 (hereinafter referred to as a high basic node) is mounted as a separate IC, which is slightly different from a basic node in which a communication IC and a CPU are integrated. This high basic node is connected to a high-speed transmission line MB1 which starts operation when an ignition switch is turned on,
It serves as a communication node that mainly controls the ABS and 4WS that need to send and receive data such as wheel speed that changes drastically with time.
The high basic node is connected to the high speed transmission line MB1 via the communication IC 101. Reference numeral 100 denotes a control CPU, which operates according to a program stored in the RAM / ROM 102. The communication IC 101 controls the protocol at the physical layer level of the CSMA / CD system. The CPU 100 has an input interface (I
A signal is input from an input auxiliary device 104 such as various sensors and switches via the / F) unit 103, and a power window motor, a door lock motor, etc. in a basic node via an output interface (I / F) unit 105. The control signal is output to the output auxiliary device 106. The electrical equipment unit described in the conventional example includes the input auxiliary device 104 and the output auxiliary device 1.
06, for example, the high basic node is an EGI controller for engine control, and the basic node is meters.

Further, the CPU 100 is a communication IC 101.
Control signal, the signal input from the input auxiliary device 104 is written in a predetermined communication frame used by another communication node, and is sent to the multiplex transmission path MB1 or MB2.
1 receives the data from the other node as a control signal and sends it to the output auxiliary device 106. That is, CPU1
00 designates the frame data on the bus as the electrical component unit 104
, Or the data from the electrical component unit 104 into a predetermined frame format. The other important role of CPU 100 is ACK
Data management. That is, as described above, in the communication system of this embodiment, when all nodes (communication IC 101 of the nodes) receive frame data from other nodes without error, an ACK bit is returned to the node of the transmission source. It is like this. Therefore, by checking the contents of this ACK field, it is possible to know which node could not receive the frame transmitted by itself. The CPU 100 is in charge of this check work. This is because the communication IC 101 is limited to communication control, and the CPU 100 performs high-level data processing.

The input signal from the input auxiliary device 104 is sent from the input interface (I / F) unit 103 to the input auxiliary device failure detection circuit unit 107. The input auxiliary device failure detection circuit unit 107 detects the failure of the input auxiliary device 104 by detecting the voltage level of the input signal from the input auxiliary device 104 and sends the failure detection signal to the CPU 100. On the other hand, the control signal output from the CPU 100 is an output driver 109 (IPS: intelligent po) with a diagnostic function.
wer switching) to the output auxiliary device 106. The IPS 109 diagnoses whether the control signal sent from the CPU 100 is normal.

The CPU 100 and communication IC 10 described above
1, the input and output I / F units 103 and 105, and the input auxiliary device failure detection circuit unit 107 are supplied with power from an external battery power supply path B via a power supply circuit unit 108. The power supply circuit unit 108 is connected to the power supply path B, regulates the drive voltage for the communication node (for example, + 5V), and then supplies power to each circuit inside the communication node.

FIG. 3 shows an example of a network system in which the above-mentioned basic node, high basic node and stand-alone node are mixed. In the example shown in FIG. 3, the basic node is the communication node 10, the high basic node is the communication node 20, and the standalone node is the communication node 30. Basic node 10
Is connected to a switch 1 such as a main switch for a centralized door lock or a power window switch. This basic node 10 serves as a node for a window opening / closing switch or the like provided on the driver's seat side door.
0 is a node for a window opening / closing switch provided on the door of each seat. As is well known, the switch at the driver's seat is capable of intensively opening and closing windows of other doors and locking the doors, so that a basic node is used. Further, in the passenger seat and the rear seat, since the windows of the individual seats are simply opened and closed, the stand-alone node 30 to which the actuator 3 such as the window opening / closing motor is connected is sufficient. That is, the opening and closing of the windows in the passenger seat and the rear seat can be performed by the basic node 10 in the driver's seat or by the respective stand-alone nodes 30. A sensor 2 such as a wheel speed sensor is connected to the communication node 20.

<Overall Network Configuration> FIG. 4 shows an overall network configuration including a high-speed transmission line and a low-speed transmission line of a multiplex communication node for controlling electrical components such as switches and motors. In the figure, instrument panel node 120, meter node 1
30, door FR (FRONT RIGHT) node 140, cowl R
The node 150 is a basic node and has a CPU for data processing inside. Also, the tail node 20
0, door FL (FRONT LEFT) 210 is a stand-alone node, ABS node 160, 4WS node 17
0, REAR node 180 is a high basic node for high speed communication. The high basic node is connected to the high speed transmission line MB1, the basic node is connected to the high speed transmission line MB1 and the low speed transmission line MB2, and the standalone node is connected to the low speed transmission line MB2.
The high speed transmission line MB1 is in a state in which the ignition switch is turned on to enable communication, and the low speed transmission line MB2 is always connected to a battery power source and is in a communicable state.

Next, main electrical components connected to each communication node shown in FIG. 4 will be described. The instrument panel node 120 is connected with a headlamp 121 for turning on the headlamp and an oil level switch 122. A warning lamp 131 and an illumination lamp 132 are connected to the meter node 130. Door FR node 1
A power window motor 141, a remote control mirror motor 142, and a power window switch 143 are connected to 40. Similarly, the door FL node 210 has a remote control mirror motor 211 and a power window motor 21.
2, the power window switch 213, and the door lock link switch 214 are connected. Cowl R node 1
A stop lamp switch 151, a sliding roof switch 152 and the like are connected to the switch 50. ABS node 160 includes wheel speed sensor 161, 4WS node 1 and the like.
A steering mechanism drive motor 171 and the like are connected to 70, and a rear wheel speed sensor 181 and a rear combination lamp 182 and the like are connected to the REAR node 180. A lamp checker 201 and a rear combination lamp 202 are connected to the tail node 200.

<Network structure of low-speed transmission line>
The network configuration of only the low-speed transmission line MB2 will be described.
FIG. 5 is a diagram showing the connection configuration of only the low-speed transmission line in the network of FIG. 4 in more detail. However, the communication node shown in FIG. 5 is a basic node or a stand-alone node having a CPU for data processing therein.
First, referring to FIG. 5, among the communication nodes shown in FIG. 5, a communication node not shown in FIG. 4 will be described.
A steering angle interlocking fog lamp motor 221 is connected to the front node 220. Also, the column node 230
The steering angle sensor 231 and the wiper intermittent volume 23.
2 is connected. ASC (auto speed control) node 240 has accelerator wire drive motor 24
1 is connected. A wiper motor 251 is connected to the MFB (main fuse box) node 250. Similarly, a duct sensor 271 is connected to the air conditioner node 270. And cowl L node 2
An air conditioner actuator 261 is connected to 60.

Among the various communication nodes connected to the low speed transmission line, the operation of the basic node will be described below.
This will be specifically described with reference to FIG. For example, focusing only on the front node 220 and the column node 230, the steering angle sensor 231 is connected to the column node,
The detected value is output to the column node every fixed period (for example, 20 ms). The front node 220 is connected to a fog lamp motor that operates in conjunction with the steering angle.
It is driven so as to turn on the fog lamp when the communication frame representing the steering angle sent from the 1-column node 220 is captured and the steering angle becomes equal to or more than a predetermined steering angle. Here, in the conventional operation, the column node that receives the detection signal from the steering angle sensor converts the detection signal into control information indicating the steering angle and writes the information indicating the steering angle in a predetermined communication frame, A communication node that requires steering angle information (in this case,
The address of the front node 220) is designated and transmitted to the multiplex transmission line. In this way, the conventional column node 23
With 0, even if the steering angle detection information sent this time is almost the same as the previous detection information, the steering angle information detected at regular intervals is sent as the latest value in the communication frame, so the detected value changes. There is a drawback that the so-called unnecessary steering angle detection information increases.

In order to overcome this drawback, the column node described in this embodiment uses the input steering angle detection value as the previous detection value when transmitting the steering angle detection information as a communication frame at regular intervals. In comparison, when the value does not change by a predetermined value (for example, 2 °) or more, it operates so as not to send the communication frame in which the detection information is written even after the elapse of a certain period.

By operating in this manner, it is possible to reduce the amount of information on the multiplex transmission line (particularly, the low-speed transmission line) and reduce the load related to the arithmetic processing of the receiver. <Control Procedure> The control procedure of the above-mentioned column node will be described below. FIG. 6 shows a control procedure of a subroutine when the detection value of the steering angle sensor in the column node 230 is sent out as a communication frame. In FIG. 6, when the process is started, in step S2, the detected value of the steering angle output from the steering angle sensor 231 is digitally converted and read every 20 ms. In step S4, the steering angle data detected this time is compared with the previous detection data. Step S6
Then, as a result of the comparison in step S4, it is calculated whether or not the steering angle has changed by 2 ° or more compared to the previous time. Step S6
If the steering angle changes by 2 ° or more compared to the previous time (YES in step S6), the process proceeds to step S8.
If it has not changed by 2 ° or more (determined N in step S6)
O), and proceeds to step S10. In step S8, the steering angle data detected this time is entered in the communication frame, the address of the front node 220 is designated, and the data is transmitted to the multiplex transmission path. Then, in step S10, the column node 2
After the previous value stored in the RAM 30 is updated to the detected value this time, the program returns to the main routine program. <Modification> It is obvious that the present invention is not limited to the above embodiment.

For example, in the above embodiment, the communication node connected to the network is not limited to the basic node. That is, a stand-alone node having no data processing function and a basic node having a data processing function are connected to the same network, and the basic node sends information data of a detected value that has changed by a predetermined value or more, and a stand-alone node. When the information data is taken in, or the communication IC of the stand-alone type node has a function of comparing the previous detected value and the detected value of this time, if the previously detected value and the detected value of this time are slightly different, this time The present invention can be applied regardless of the number of nodes of any type connected to the network.

Further, it goes without saying that the present invention can be applied to other than the control of the fog lamp based on the steering angle sensor. For example, in FIG. 5, M based on the detection value of the intermittent wiper volume sensor 232 of the column node 230.
Control of the wiper motor 251 of the FB node 250, control of the air conditioner actuator 261 of the cowl L node 260 based on the detection value of the duct sensor 271 of the air conditioner node 270, MFB node 250
Control of the accelerator wire drive motor 241 of the ASC node 240 based on the detection value of the vehicle speed sensor sensor 252, or control of the illumination lamp 132 of the meter node 130 based on the detection value of the panel brightness volume sensor 123 of the instrument panel node 120. Or, various cases can be applied.

[0030]

As described above, according to the multiplex transmission apparatus of the present invention, the communication node transmits the periodic control information when the change amount of the detection value of the sensor or the like does not exceed the predetermined value. Since there is no bus traffic, and the CPU load due to the increase in ROM / RAM capacity of the communication node is reduced, it is possible to prevent the operation delay of the actuator and the like.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a frame format used in a conventional communication system.

FIG. 2 is a diagram showing a detailed configuration of a communication node having a CPU used in a multiplex transmission network of an automobile of this embodiment.

FIG. 3 is a diagram showing an example of a network system in which basic nodes, high basic nodes, and stand-alone nodes are mixed.

FIG. 4 is a diagram showing an entire network configuration including a high-speed transmission path and a low-speed transmission path of a multiplex communication node that controls electrical components such as switches and motors.

5 is a diagram showing in more detail the connection configuration of only low-speed transmission lines in the network of FIG.

FIG. 6 is a flowchart showing a control procedure of a column node.

[Explanation of symbols]

MB1, MB2 ... Multiplex transmission line 10 ... Basic node 20 ... High basic node 30 ... Standalone node 240 ... Auto speed control node 250 ... Main fuse box node 270 ... Air conditioner node

Continuation of the front page (56) References JP-A-5-14365 (JP, A) JP-A-6-30003 (JP, A) JP-A-60-247347 (JP, A) JP-A-62-55704 (JP , A) JP 60-76840 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04L 12/40

Claims (3)

(57) [Claims] 1. A first communication node connected to a high-speed communication line.
And a second communication node connected to the low speed communication line.
In the multiplex transmission apparatus comprising: the second communication node , means for detecting whether or not a predetermined event has occurred, and, when the predetermined event has occurred, a change amount of event data based on the predetermined event. means for calculating, when the change amount of the event data does not exceed a predetermined value, and means for inhibiting the transmission of the communication frame with the events <br/> elephants data
Comprising a first communication node, compared with the second communication node
A multiplex transmission device characterized by transmitting and receiving event data that changes rapidly over time . 2. A first communication node connected to a high-speed communication line.
And a second communication node connected to the low speed communication line.
In the multiplex transmission apparatus including: the second communication node, means for detecting whether a predetermined event has occurred, and based on the predetermined event, when the predetermined event has occurred
Means for calculating the amount of change in the event data, and if the amount of change in the event data does not exceed a predetermined value,
Means for prohibiting transmission of a communication frame having data
Comprising a said second communication node, as compared to the first communication node
Is set to a small memory capacity, or the CPU
A multiplex transmission device characterized in that the calculation processing speed is set low . 3. The high speed communication line is a vehicle ignition.
When the power switch is turned on, communication is possible and
The low speed communication line is connected to the vehicle's battery
The multiplex transmission device according to claim 1 or 2 , which is in a receivable state .