JPH098832A - Multiplex transmission method - Google Patents

Abstract

(57) [Abstract] [Purpose] To store the transmission request data in a normal data transmission frame and reduce the traffic on the transmission path. [Configuration] Nodes 1 to 5 are mutually connected via a transmission line MB, and each node has loads SW1 to SW connected to itself.
Unique data created based on data from 5 etc.
Sends a frame to another node via the transmission path, receives a frame on the transmission path, processes the data of the reception frame according to a predetermined procedure when the reception frame is addressed to itself, and selects the transmission node of the nodes. In the multiplex transmission method for requesting a receiving node to transmit a frame of self-specific data, the transmitting node transmits a frame including self-specific data and a transmission request bit indicating a transmission request in the ON state. , Allows return of unique data from the receiving node.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplex transmission method for transmitting frame data by being connected to a common transmission line.

[0002]

2. Description of the Related Art Conventionally, in a system using this type of multiplex transmission method, a multiplex transmission device (hereinafter referred to as a "node") is connected to a transmission line composed of a twisted pair electric wire to construct a multiplex communication network. As a transmission method, for example, CSMA / CD (Carrier Sense Multiple Acces
s / Collision Detection) transmission method, for example, it is used in a local area network (LAN) for multiplex transmission of data in an automobile.

As shown in FIG. 8, the node 30 is connected to a transmission line MB via a bus interface circuit 31, and frame-structures data with other nodes (not shown) on the transmission line MB. Is being transmitted. In the node 30, the communication control circuit 32 generates frame transmission data based on the input data of the switch SW or a sensor (not shown) input to the input port 33 via the input circuit 34, and via the bus interface circuit 31. Transmission line M
Send to B.

Further, the communication control circuit 32 receives the frame of the transmission path MB via the bus interface circuit 31, checks whether there is an error in the received frame, checks the identifier bit string, and so on.
It is determined whether the frame should output data to the load (motor M, lamp R) connected to its own node. Then, in the case of a frame to be output, the communication control circuit 3
2 outputs the above data to the output latch 35 and drives the motor M, the lamp R and the like via the output circuit 36. Further, at the node 30, power is supplied from an external battery, and the power circuit 37 supplies a power voltage of, for example, 5 V to the inside.

In the above-mentioned multiplex transmission system, for example, when the system is started immediately after the power is turned on, it is necessary to know what kind of state the load controlled by the own node is in the initial state. Therefore, each node transmits a data request frame in order to receive the data required by the own node from other nodes. Then, the node that receives the data request frame returns the frame to the node that is the transmission source, and the initial state has been fixed.

[0006] One of such transmission methods is, for example, that the node making the data request transmits a data request frame including an identifier bit string corresponding to the data requested by the own node. Some request data from a node. The node receiving the data request frame checks the identifier bit string of the received frame and returns the data bit string corresponding to the identifier bit string in a frame structure.

Since the data requesting node transmits the data requesting frame with the identifier corresponding to the data requested by the node, if the data requesting frame and the normal data transmitting frame have the same structure. Cannot distinguish between the data request frame of its own node and the return frame from another node.For example, the data request frame does not include a data bit string, so it can be used for normal data transmission. I had to change the frame and composition.

[0008]

However, in the above-mentioned multiplex transmission method, when data from another node is needed, a data request frame different from a normal frame must be transmitted. However, there is a problem that the amount of traffic on the transmission line increases.

The present invention has been made in view of the above problems, and provides a multiplex transmission method capable of reducing transmission traffic by storing transmission request data in a normal data transmission frame. The purpose is to do.

[0010]

In order to achieve the above object, according to the present invention, a plurality of nodes are connected to each other via a transmission line, and each node is connected to, for example, a load connected to an input port of the node ( Data such as switches and sensors) and unique data created based on this data,
A predetermined procedure of transmitting a frame on the transmission line to the other at least one multiplex node via the transmission line, receiving the frame on the transmission line, and if the received frame is addressed to itself, sets the data of the received frame in advance. The first node (sending node) of the nodes is
In the multiplex transmission method for requesting the node (reception node) to transmit a frame containing self-specific data, the transmission node requests the reception node to transmit data unique to the reception node at the time of system startup. To
Transmitting a frame including at least the self-specific data and data indicating the transmission request, the receiving node, when receiving a frame addressed to itself, according to the content of the data indicating the transmission request of the frame, Frame transmission of self-specific data.

According to a sixth aspect of the present invention, the data indicating the transmission request is transmitted by being stored in all or a part of a bit area of a predetermined area such as an identifier or a control data area among the areas forming the transmission frame. It

[0012]

When the system starts, the transmitting node transmits a frame containing its own unique data and data indicating a transmission request in the ON state (transmission request bit), and returns the unique data from the receiving node. By enabling this, it becomes possible to transmit data to another node and acquire the data of the own node.

According to the present invention, the transmission request bit is stored in a conventionally provided identifier or control data area to prevent an increase in frame length.

[0014]

Embodiments of the present invention will be described with reference to the drawings of FIGS. FIG. 1 is a configuration diagram showing an example of the configuration of a system using the multiplex transmission method according to the present invention. FIG.
With reference to FIG.
5 and a transmission line MB to which the nodes 1 to 5 are connected. These nodes are connected to a transmission line MB via a bus interface circuit described later, and transmit frame structure data to other nodes on this transmission line MB. In the multiplex transmission system according to the present invention, the topology of the transmission line is a bus type, a ring type,
Alternatively, any type such as a star type can be applied.

As a concrete example of the multiplex transmission system according to the present invention, it is used, for example, for controlling an electric system in an automobile, and a switch, a sensor and an actuator are arranged from their respective locations via a harness (electric wire in the automobile). Connected to the appropriate node and configured. That is, the instrument panel (hereinafter, referred to as “instrument panel”) node 1 is arranged in the vicinity of the meters ME1.
For example, the meter ME1 is driven by the data from the vehicle speed sensor S1 from the engine node 4, and the ON / OFF signal of the door switch SW1 from the door node 5 lights the indicator lamp in the meter ME1. Further, the instrument panel node 1 has a power window switch SW for driving the power window motor M1.
2 is connected.

The front node 2 is arranged on the front surface of the vehicle and has a headlamp switch SW from the cowl node 3.
3. The headlight R1 and the turn signal lamp R2 on the front of the vehicle are driven by the ON / OFF signal of the turn signal switch SW4. The cowl node 3 is arranged in the vicinity of the cowl portion, and is connected to a headlamp switch SW3, a turn signal switch SW4, and a door lock switch SW5 for driving the door lock motor M2.

The engine node 4 is arranged in the vicinity of the engine and is connected to a vehicle speed sensor S1 to control the engine / transmission. This control is performed by the microcomputer in the node based on the data of the vehicle speed sensor S1 and the like. Further, the engine node 4 has a vehicle speed sensor S1.
The data of the sensor is transmitted to each node, such as by encoding the data of (1) and transmitting it to the instrument panel node 1.

The door node 5 is arranged near the door,
The door switch SW1, the power window motor M1 and the door lock motor M2 are connected. The door switch SW1 is turned on when the door is open, and this on signal is transmitted from the door node 5 as a signal for lighting the indicator lamp in the instrument panel node 1.
Further, in the door node 5, the power window motor M1 is driven by the ON / OFF signal of the power window switch SW2 from the instrument panel node 1 to raise and lower the window. Further, the door node 5 is the cowl node 3
Door lock motor M2 is driven by the ON / OFF signal of door lock switch SW5 from
Lock is released.

In the above-mentioned multiplex transmission system, a physical address usually corresponds to one node on a one-to-one basis. In this embodiment, this address corresponds to 4-bit data (A
3, A2, A1, A0). For example, the instrument panel node 1 has an address 0 (0000), the front node 2 has an address 4 (0100), and the cowl node 3 has an address 8 (1000). Address 12 (1100) is assigned to the engine node 4, and address 15 (1111) is assigned to the door node 5. The address allocation is not limited to that of this embodiment, and other addresses can be set as long as they are optimally allocated as a system.

FIG. 2 is a diagram showing an example of a format of a data frame transmitted between nodes via the transmission path MB. Referring to FIG. 2, this data frame is an SOF (Start Of Frame) indicating the beginning of the frame.
When a plurality of nodes simultaneously send data to the transmission path MB, the priority (PR
I), an identifier (ID) indicating the content of each subsequent data (DATA), a control data area (CONT) including data indicating the data length, and a data area having a length (variable length) indicated by CONT For example, DATA1 to DATA4 for each 8 bits and C of the error check code
RC and EOD (End Of Data) indicating the end of data
And, for example, a 24-bit ACK signal area for returning a reception confirmation signal (hereinafter referred to as “ACK signal”) from all nodes corresponding to bits, and an ACK signal is returned from all the registered nodes for data transmission. Is composed of a 1-bit ACK confirmation bit area indicating the end of the frame and an EOF (End Of Frame) indicating the end of the frame.

As such a node, two types of configurations shown in FIGS. 3 and 5 below can be considered. Referring to FIG. 3, the node 10 of the first embodiment realizes a data input / output control function by hardware and does not require a micro computer. This node 1
0 is a bus interface circuit 11 and a communication control circuit 1
2, an input circuit 13, an input port 14, an output circuit 15, an output port 16, a port control unit 17, a transmission buffer memory (hereinafter, referred to as "transmission buffer") 18 for storing transmission data, a reception for storing received data Buffer 1
It is composed of 9 and 9.

The input circuit 13 takes in input signals from loads such as various switches SW and sensors (not shown) as parallel signals and outputs them to the input port 14. The port control unit 17 monitors the value indicated by various input signals input to the input port 14, and sends a value of this input signal to the communication control circuit 12 when a part or all of this value changes. The communication control circuit 12 stores the value of the input signal as input data in the transmission buffer 18, generates a frame based on the data, and transmits the frame to the transmission path MB via the bus interface circuit 11. In this case, the input port 14 has a 16-bit configuration of an input port A and an input port B each having 8 bits. Further, in the above case, the number of connection terminals of the input port may be larger than the number of loads connected via the input circuit and may be left over. In such a case, the connection terminals of the surplus input ports are connected to the ground or the power source, but in the present embodiment, the input signals from the connection terminals of the surplus input ports are also taken in as the input signals from the load. And

In the concrete transmission frame generated in this way, as shown in FIG. 4A, each bit of the input port 14 is made to correspond one-to-one with each bit of the data area of the transmission frame. . That is, in this example, bits 7 to 0 of the input port A are bits 7 to 7 of DATA3.
0, each of bits 7 to 0 of input port B is DAT
It corresponds to bits 7 to 0 of A4, respectively.

The communication control circuit 12 also receives the signal on the transmission line MB via the bus interface circuit 11. Then, by detecting the start bit, it is recognized that the received frame is transmitted to the transmission path, and this data is temporarily stored in the reception buffer 19. Upon recognizing the received frame, the communication control circuit 12 causes the CONT and ID
Determines whether the received frame is necessary for the node itself. Here, if this reception frame is necessary for the own node and reception is completed without error, the data fetched in the reception buffer 19 is transferred to the port control circuit 1.
Send to 7.

The port control circuit 17 outputs this data to the corresponding output port 16 and outputs it to a desired load such as the motor M and the lamp R via the output circuit 15 to drive this load. Here, the output port 16 has a 16-bit configuration of the output port A and the output port B each having 8 bits. In the specific received frame thus received, as shown in FIG. 4B, each bit of the output port 16 is made to correspond one-to-one with each bit of the data area of the received frame. That is, in this example,
Bits 7 to 0 of the output port A correspond to bits 7 to 0 of DATA3, and bits 7 to 0 of the output port B correspond to bits 7 to 0 of DATA4.

In this node 10, the communication control circuit 12,
Input port 14, output port 16 and port control circuit 1
7 is an example in which it is composed of one communication IC. Since this node 10 does not have a microcomputer for communication control (hereinafter referred to as "I / O node"), the transmission frame and the reception frame read the value input from the address setting input terminal or the like, Those that can be easily generated are desirable. Specifically, the priority is
It is determined by the value of the input terminal for address setting, the IDs of the transmission frame and the reception frame are also determined by the physical address of each node, etc., and the number of terminals is reduced by not providing a dedicated setting terminal, and the scale of the communication control circuit 12 is reduced. Is small.

If the ID of the transmission frame and the ID of the reception frame are the same, the transmission frame of its own node and the transmission frame of another node cannot be distinguished. For this reason, it is conceivable that the transmission data of the own node will be received and the load will be driven. Therefore, for example, the logical value of the last bit of the ID is changed and the like
And different IDs for determining that the data should be received.

That is, referring to FIG.
D is 8-bit data, and the 0th bit of ID is
The transmission frame of FIG. 4 (a) is set to logic "0", and the reception frame of FIG. 4 (b) is set to logic "1". Further, in the 4th to 1st bits of the ID, the address values A3, A2, and
A1 and A0 correspond. The 7th to 5th bits of ID are
For example, it is conceivable that all are fixed to logic "1" to distinguish between transmission / reception frames of I / O nodes.

Since the I / O node does not have a microcomputer, it is not a node for performing complicated control of a meter or the like, and does not require control functions such as input of switch on / off data and signal output for lighting a lamp. It is suitable to use as a node dedicated to various input / output. In FIG. 1, the front node 2 and the engine node 4 correspond to this I / O node.

Referring to FIG. 5, the node 20 of the second embodiment includes a bus interface circuit 21, a communication control circuit 22, an input circuit 23, an input port 24, an output circuit 25,
Output port 26, CPU core 27, transmission buffer 28,
It is composed of a reception buffer 29. This node 2
In 0, the communication control circuit 22, the input port 24, the output port 26, and the CPU core 27 are configured by one communication IC.

The CPU core 27 reads the signal of the switch SW via the input port 24 and sends it to the communication control circuit 22 as data. Then, when a transmission start signal is input from the CPU core 27, the communication control circuit 22 sends this data to the bus interface circuit 21 in a frame format. When the communication control circuit 22 receives a frame from the transmission path MB via the bus interface circuit 21, the communication control circuit 22 stores the data in the frame in the reception buffer 29 and notifies the CPU core 27 that the frame has been received. CPU core 27 that received this notification
Captures the data stored in the receive buffer 29,
Based on the CONT and ID in the frame, it is determined whether or not this frame is necessary for the own node. Here, the CPU core 27 controls the load connected to the output circuit 25 according to the received data when the reception of the frame necessary for the own node is completed without error.

In the node (hereinafter, referred to as "Basic node") 20 which controls communication by such a microcomputer,
I corresponding to the transmission frame or the reception frame of its own node
It is possible to store D by providing a dedicated storage area in the RAM or the like of the microcomputer as an initial setting when the node rises. As a result, the Basic node 20 can communicate in a plurality of frames, that is, frames with different IDs, can increase the number of signals to be transmitted and received, and can be used for a node that needs a control function for controlling a plurality of meters or the like. Is suitable. In FIG. 1, the instrument panel node 1, the cowl node 3 and the door node 5 correspond to this Basic node.

Next, FIG. 6 shows a concrete example of a transmission / reception frame in the multiplex transmission system shown in FIG. In this multiplex transmission system, as described above, the instrument panel node 1, cowl node 3 and door node 5 are the basic nodes having the configuration shown in FIG. 5, and the front node 2 and the engine node 4 are those having the configuration shown in FIG. I / O node.

Although the engine node 4 performs complicated control of the engine and transmission, such control may be performed by a dedicated microcomputer. In that case,
Instead of the input circuit 13 and the output circuit 15 shown in (1), it is possible to configure an I / O node for input / output control by connecting a microcomputer between the load and the communication IC. More specifically, since this I / O node is composed of a communication control circuit that transmits a frame in response to a change in the input port, when a vacant input port is connected to the output port of the microcomputer and a frame is transmitted. To enable frame transmission, the microcomputer changes its output port. In this case, since the microcomputer can arbitrarily change the input port value of the input port 14, the data transmission interval can be freely set. Note that this I
In the / O node, the data of the vehicle speed sensor S1 is calculated by the microcomputer as the period of the pulse output from the vehicle speed sensor S1, and the value is coded into 4-bit data here and input to the input port 14 of the communication IC. For example, the one to be transmitted is described below. Also, when the output port of the I / O node is connected to the input port of the microcomputer and the communication control circuit outputs the data received from the transmission path, the microcomputer controls the engine transmission based on the data.

Referring to FIG. 6, (a) is a frame transmitted from the cowl node 3 to the front node 2 by DATA.
The 6th bit of 3 corresponds to the data of the headlamp switch SW3, and the 5th bit corresponds to the data of the turn signal switch SW4. Since this frame is a reception frame of the front node 2 which is an I / O node, the ID is "11101001" as described with reference to FIG.

FIG. 6 (b) is a frame transmitted from the engine node 4 to the instrument panel node 1, and corresponds to the data of the vehicle speed sensor S1 encoded in 4 bits from the 6th bit to the 3rd bit of DATA3. I am letting you. The signal of the vehicle speed sensor S1 is a signal for driving the meter ME1, and the vehicle speed is a continuous signal, and therefore needs to be frequently transmitted cyclically at intervals of, for example, several 100 ms. Since this frame is a transmission frame of the engine node 4 which is an I / O node, the ID is "11111000" as described with reference to FIG.

FIG. 6 (c) is a frame transmitted from the cowl node 3 to the engine node 4, and the data of the headlamp switch SW3 is associated with the sixth bit of DATA3. Since this frame is a received frame of the engine node 4 which is an I / O node, the ID is "11111001" as described with reference to FIG. Figure 6 (d) shows
In the frame that the cowl node 3 transmits to the door node 5,
Door lock switch SW5 at the 7th bit of DATA3
Corresponding to the data of. This frame is a transmission / reception frame between Basic nodes, but here, insert the address value of the door node 5 which is the receiving node into the ID,
It is set to "00011111". In the anode 5,
Since the frame of this ID is a frame necessary for its own node, this ID is stored in the RAM of the microcomputer in advance.

FIG. 6 (e) is a frame transmitted from the instrument panel node 1 to the door node 5, and the data of the power window switch SW2 is associated with the sixth bit of DATA3. Since the data of the power window switch SW2 is a signal of the door control system like the data of the door lock switch SW5, the ID of this frame is shown in FIG.
As in the frame of (d), "00011111" is set.

The instrument panel node 1 and the cowl node 3
Transmits a frame with the same ID, therefore, in this frame, DATA1 indicates valid / invalid indicating that data is valid / invalid.
An invalid bit function (hereinafter referred to as "V / I") is introduced. This V / I is DAT for each bit of DATA3.
Each bit of A1 is made to correspond. That is, this V /
For I, D corresponding to the bits required for DATA3 control
The logical value of the bit of ATA1 is set to “0”, and the logical value of the bit of DATA1 corresponding to the bit unrelated to the control of DATA3 is set to “1” to determine which data bit of the frame is for control at the receiving node. It was made possible.

In the frame of FIG. 6 (d), the 7th bit is data necessary for control, but the 6th bit is irrelevant data. Therefore, the 7th bit of DATA1 is set to logic "0". , And the sixth bit is a logic "1". In the frame of FIG. 6 (e), the 6th bit is data necessary for control, but the 7th bit is irrelevant data. Therefore, the 7th bit of DATA1 is set to logic "1". , The 6th bit is set to logic "0".

If this V / I is not introduced, for example, the instrument panel node 1 transmits the ON signal of the power window switch SW2, and the cowl node 3 transmits the OFF signal of the door lock switch SW5 while the window is open. It is possible to send it. In this case, cowl node 3
Has no data of the power window switch SW2, the sixth data of DATA3 in the frame of FIG.
The bit data is not always transmitted with the correct value. Nevertheless, the door node 5 performs control based on this transmission frame because the ID of the transmission frame of the cowl node 3 is also the ID indicating the self node which is the receiving node. Therefore, this open window may be closed. Therefore, it becomes necessary to assign different IDs to these signals.

Therefore, if V / I is introduced as in this embodiment, the door lock switch SW is switched from the cowl node 3 to the door lock switch SW.
If the sixth bit of DATA3 is designated invalid when transmitting 5, it is possible to prevent malfunction even when transmitting a frame with the same ID. FIG. 6 (f) is a frame transmitted by the door node 5 to the instrument panel node 1, and the data of the door switch SW1 is associated with the 7th bit of DATA3. This frame is a transmission / reception frame between Basic nodes, but here, by inserting the address value of the instrument panel node 1 which is the receiving node into the ID, “0000000” is inserted.
In the instrument panel node 1, since the frame of this ID is a frame necessary for its own node, this ID is stored in the RAM of the microcomputer in advance.

In the above-mentioned multiplex transmission system, there is no problem in the function that operates even when the ignition switch is off, like a headlamp, but in the function that does not operate when the ignition switch is off, such as engine control and a meter, the system does not operate. At the rising edge of, each node does not know what state the load it controls should be.

Therefore, in this embodiment, a specific bit in a frame is defined as a transmission request bit, and the transmitting node turns off the transmission request bit and transmits a frame (hereinafter A "normal frame") is transmitted, and when requesting data from another node, a frame with the transmission request bit turned on (hereinafter referred to as "transmission request frame") is transmitted.

Here, the transmission request bit is a specific one bit in the frame, and even if the on / off is determined by its logical value, a combination of a plurality of bits, for example, in CONT which is a predetermined area in the frame. It may be determined to be ON by a combination of logical values of a plurality of bits. In addition, the other areas forming the frame are set in the same manner for both the normal frame and the transmission request frame.

An example in which the I / O node transmits a transmission request frame in the communication between the I / O node and the Basic node will be described. The I / O node is
Send a transmission request frame. When the system is started up, for example, the power of each node is started up, the reset is released, or the low power consumption mode is released. The low power consumption mode is a mode in which while the ignition switch is off, the current consumption is reduced and the operation is stopped in order to reduce the load on the battery, and only the input change of the switch signal or the like is monitored.

Here, a specific example of the transmission frame in the multiplex transmission system will be described. The engine node 4 which is an I / O node, as shown in FIG.
It is determined that this frame is a transmission request frame by the combination of the logical values of the upper 3 bits of the 8-bit data in the area. In this embodiment, the engine node 4 needs the data for engine control when the system starts up, and therefore transmits the transmission request frame requesting the data of the headlamp switch to the cowl node 3. That is, the normal frame transmitted by the engine node 4 has the logical value of the upper 3 bits in the CONT area is "011" as shown in FIG. ), The upper 3 bits are transmitted as “101”. That is, the engine node 4 simply turns on the transmission request bit when transmitting the transmission request frame, and the vehicle speed sensor data is stored in the third to sixth bits of DATA3 as in the frame of FIG. 6B. The inserted request frame can be transmitted.

The cowl node 3, which is a basic node, checks the CONT area and ID of the frame of the transmission path and confirms that the frame is a transmission request frame from the engine node 4 based on a combination of logical values. The cowl node 3 is set to ignore the data of the frame when the ID is “11111000”. Since the cowl node 3 responds to the data request of the transmission request frame shown in FIG. 7B transmitted from the engine node 4, the cowl node 3 returns the frame shown in FIG. 6C.

On the other hand, in the instrument panel node 1 which is a basic node, when the frame having the ID "11111000" is received, the data of the frame is validated,
Set so that the frame is not returned even if the transmission request bit is turned on. Therefore, in this embodiment, since the data normally transmitted by the engine node is contained in the DATA area of the transmission request frame from the engine node, it is not necessary to transmit a frame for transmitting data in addition to the transmission request frame. The efficiency of data transmission can be improved.

In the above embodiment, the transmission request bit is designated by the specific bit in the CONT area. However, in the case of communication between Basic nodes, the transmission request frame is set at the specific ID. It can be set in advance.
A specific example thereof will be described using another example of the transmission request frame in FIG. When the cowl node 3 and the instrument panel node 1 receive the frame with the ID “00011110” shown in FIG. 7 (c), they recognize that the frame is a transmission request frame from the door node 5, and respectively see FIG. 6 (d). , (E) frame is returned. In this case, by using the V / I indicating the validity / invalidity of data, it is possible to make a transmission request to a plurality of nodes in one transmission request frame, and it is possible to further improve the efficiency of data transmission.

[0051]

As described above, according to the present invention, a plurality of multiplex transmission devices are mutually connected via a transmission line, and each multiplex transmission device transmits its own unique data via the transmission line. While transmitting in a frame configuration to at least one other multiplex transmission device, receiving the frame on the transmission path, if the received frame is addressed to itself, process the data of the received frame in a predetermined procedure, In a multiplex transmission method in which a first multiplex transmission device of the multiplex transmission devices requests a frame transmission including self-specific data to another second multiplex transmission device, the first multiplex transmission device comprises:
When requesting the second multiplex transmission apparatus to transmit data unique to the second multiplex transmission apparatus when the system is started up, at least the self-specific data and data indicating the transmission request are included. When a frame is transmitted and the second multiplex transmission device receives a frame addressed to itself,
Since the unique data is frame-transmitted according to the content of the data indicating the transmission request of the frame, the transmission request data should be stored in the normal data transmission frame to reduce the traffic amount of the transmission path. You can

In the present invention, the data indicating the transmission request is stored in the bit area of all or a part of the predetermined area of the area forming the transmission frame and is transmitted. Therefore, the frame length is increased. It can be prevented.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a multiplex transmission system using a multiplex transmission method according to the present invention.

FIG. 2 is a configuration diagram showing an example of a format of a data frame transmitted between the nodes shown in FIG.

FIG. 3 is a configuration block diagram showing a configuration of a first embodiment of a node according to the present invention.

FIG. 4 is a configuration diagram showing a specific example of the data frame shown in FIG.

FIG. 5 is a configuration block diagram showing a configuration of a second exemplary embodiment of a node according to the present invention.

6 is a configuration diagram showing a part of each data frame transmitted / received between the nodes shown in FIG. 1. FIG.

7 is a configuration diagram showing a part of a normal frame and a transmission request frame transmitted / received between the nodes shown in FIG.

FIG. 8 is a configuration block diagram showing a configuration of a conventional node.

[Explanation of symbols]

 10, 20, 30 Multiplex transmission device (node) 11, 21, 31 Bus interface circuit 12, 22, 32 Communication control circuit 13, 23, 34 Input circuit 14, 24, 33 Input port 15, 25, 36 Output circuit 16, 26 Output Port 17 Port Control Circuit 18, 28 Transmission Buffer Memory 19, 29 Reception Buffer Memory 27 CPU Core MB Transmission Line

Front page continuation (72) Inventor Yoshikazu Nobutoki, 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture, Mazda Co., Ltd. (72) In-house, Hiroaki Sakamoto, 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture, Mazda Co., Ltd.

Claims (8)

[Claims] 1. A plurality of multiplex transmission devices are connected to each other via a transmission line, and each of the multiplex transmission devices transmits data unique to itself to at least one other multiplex transmission device via the transmission line. The first multiplex of the multiplex transmission device is configured to transmit the frame, receive the frame on the transmission path, and process the data of the received frame in a predetermined procedure when the received frame is addressed to itself. The transmission device is
In the multiplex transmission method of requesting another second multiplex transmission apparatus to transmit a frame containing self-specific data, the first multiplex transmission apparatus may transmit the second multiplex transmission apparatus to the second multiplex transmission apparatus. When requesting transmission of data unique to a transmission device, a frame including at least the data unique to the self and the data indicating the transmission request is transmitted, and the second multiplex transmission device transmits a frame addressed to itself. Upon reception, a multiplex transmission method characterized by transmitting self-specific data in a frame in accordance with the content of data indicating a transmission request for the frame. 2. The data unique to the multiplex transmission device comprises at least one of data from a load connected to the multiplex transmission device or data created based on the data from the load. The multiplex transmission method according to claim 1. 3. The multiplex transmission method according to claim 1, wherein the transmission frame for requesting the transmission is transmitted at the time of system startup. 4. The system starts up when the multiplex transmission device is powered on, when reset is released, or when the low power consumption mode is released.
The multiplex transmission method described in. 5. The multiplex transmission method according to claim 1, wherein the transmission frame includes information indicating validity or invalidity of data in the frame. 6. The data indicating the transmission request is stored in a bit area of all or a part of a predetermined area of the area forming the transmission frame and transmitted. Multiplex transmission method. 7. The multiplex transmission method according to claim 6, wherein the predetermined area is an area in which data indicating a data length in the transmission frame is stored. 8. The multiplex transmission method according to claim 6, wherein the predetermined area is an area in which data indicating the content of each data in the transmission frame is stored.