JP3164402B2 - Multiplex transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a so-called CSMA / CD (Carr
The present invention relates to a multiplex transmission method using an ier Sense Multiple Access / Collision Detection) transmission method.

[0002]

2. Description of the Related Art Conventionally, in this type of multiplex transmission system, one of a plurality of terminals (multiplex nodes) commonly connected to a multiplex transmission line (multiplex bus) composed of a pair of wires is connected to a CSMA / MS. According to the CD method, a data frame as shown in FIG. 13 is transmitted to the multiplexed bus, data is simultaneously transmitted to other multiplexed nodes, and an acknowledgment signal (ACK signal) area is provided at the end of the data frame. It has been proposed that each multiplex node receiving a data frame returns an ACK signal to a pre-assigned bit position in the ACK signal area.

[0003] The data frame shown in FIG. 13 has a message format normally transmitted and received by the multiplex transmission method, and has a start of message (SOM) indicating the start of the message.
When a plurality of multiplex nodes transmit data to a multiplex bus at the same time, the priority (PR
I), a message I indicating the content of each subsequent data (DATA)
D, error check code such as control data area (CONT) containing data indicating data length, data area (DATA1 to DATA4) of length (variable length) indicated by CONT, CRC (cyclic code), etc. EOD (End OfDa
ta), an ACK signal area for returning an ACK signal in bit correspondence from all multiplex nodes, and an EOM (End Of Message) indicating the end of the message.

Each of the multiplex nodes is equipped with a computer for communication. The computers operate independently of each other, and transmit the data frame shown in FIG. 13 to the multiplex bus at an arbitrary timing. Can be. For this reason, message collision may occur on a multiplex bus. To prevent this, in the past, priorities were assigned to messages, and as shown in the transmission procedure of FIG. 14, each computer destroyed the messages. Data transmission is performed by the non-destructive arbitration-type CSMA / CD access method in which priority control is performed without interruption, transmission of low priority messages is automatically interrupted, and transmission of only high priority messages is continued. Each of the multiplex nodes returns an ACK signal to a location corresponding to a unique address assigned to each node when data reception ends normally.

Although the ACK signal area can be composed of various transmission codes, each multiplex node is composed of a PWM (pulse width modulation) signal as shown in FIG. 15 so that each multiplex node can easily return and receive the ACK signal. There are things to be done. In the PWM signal, one logical bit is divided into three small bit sections (hereinafter, referred to as “phase”), and the first phase is fixed at an active signal level, and the third phase is fixed at a passive signal level. By expressing the second phase by an active signal level or a passive signal level, a state of logic “0” and logic “1” is formed.

[0006] Each of the multiplex nodes returns an ACK signal to a location corresponding to a unique address assigned to each node when data reception is normally completed. Therefore, in the ACK signal area, as shown in FIG.
At the first phase of each bit of the CK signal area, an active signal is transmitted on the multiplex bus, and the other receiving multiplex nodes transmit bit frames (ACK signal) assigned to their own stations from the transmitted data frame. The rising edge of the first phase of the region is detected, the multiplex bus is activated at the same time, and the active state is continued until the second phase, so that the bit indicates a logical "0". Further, when the data reception is not performed normally, even if the rising edge of the first phase of the corresponding bit area is detected, the second phase is kept in the passive state without activating the multiplex bus. The bit indicates a logical "1".

Here, if a local error occurs on the network and there is an error in the received data at a given multiplex node, the given multiplex node does not return an ACK signal. And retransmit the data. The transmission multiplex node repeats data retransmission up to three times, for example, until all registered multiplex nodes return ACK signals. If there is a node that does not return an ACK signal even after retransmission three times,
The above node is considered out of order and removed from registration.
When the number of ACK signals increases, a node corresponding to the ACK signal is newly added to have an ACK management function.

[0008]

However, in the above multiplex transmission system, since the data from each multiplex node is in a separate frame, each multiplex node wants to obtain data from a plurality of multiplex nodes simultaneously. However, since the delay time varies depending on the traffic, the arrival time of each frame may vary greatly. For example, even if an operation is performed based on the above data and new control is performed, the above control may not be performed. There was a point.

On the other hand, it is conceivable to use a time slot method for collecting data from a plurality of multiplex nodes in one frame. However, in this method, a synchronization signal such as a synchronization pulse indicating a data break from a specific node is used. The need to generate a signal arises, and it becomes a centralized control type. For example, when each data obtained simultaneously from a plurality of multiplex nodes is used for multi-function control by a plurality of multiplex nodes, the above method cannot be used. There was a problem. That is, there is a problem that any multiplex node cannot arbitrarily generate a transmission request for simultaneous data collection as needed.

In addition, CS for performing contention for each bit
In the MA / CD transmission method, a method in which the subordinate node transmits data in part of the frame generated by the main node can be considered,
There are problems that need to be solved, such as how to synchronize a plurality of multiple nodes and how to perform an error check method for collecting data. The present invention has been made in view of the above problems, and can collect data from a plurality of multiplex nodes on a network at the same time, accurately check errors of these data, and improve the efficiency of data transmission. It is intended to provide a multiplex transmission system.

[0011]

In order to solve the above-mentioned object, according to the present invention, there are provided a plurality of multiplex nodes connected to each other via a common multiplex transmission line, wherein the multiplex nodes mutually exchange data for each frame. In the multiplex transmission method for transmitting the data, the data area of the transmission request frame transmitted from the predetermined multiplex node is set to the first field for inserting the transmission data from the own station .
A second area for inserting the transmission data of each multiplex node that performs data transmission in response to the transmission request.
Data area, and the predetermined multiplex node
In the data area 1, when transmitting a frame,
The verification data in the frame according to the transmission data of the station
In the second data area, and in the second data area, in the frame in accordance with the received data from each of the multiplex nodes .
Generate and transmit matching data, wherein each of said multiple nodes
The transmission data is transmitted in a predetermined order to the local station data insertion area of the divided data area, and the local station data is transmitted.
In the data insertion area, the
To generate matching data in the frame,
In the second data area other than the own station data insertion area
The frame in accordance with the data received from each multiplex node.
The collation data generated in the
Data and the matching data received from the predetermined multiplex node.
Comparison, and mutual data transfer is normal according to the comparison result
A multiplex transmission method for determining whether or not the transmission has been performed is provided.

[0012]

The predetermined multiplex node divides the data area of the transmission frame, causes each multiplex node that has requested transmission to transmit data to the data area in a predetermined order, and exchanges data with each other. Therefore, data can be simultaneously collected from multiple nodes that are functionally dependent.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a non-destructive arbitration type CSMA / C according to the present invention.
1 is a system configuration diagram of a multiplex transmission system for a vehicle using a D access method. In the figure, an engine computer 11 for controlling a fuel injection amount and an ignition timing, and an antilock traction computer 1 for controlling a driving force and a brake
2. A transmission computer 13 for controlling the transmission and four wheels, ie, a front light (F
R), front left (FL), rear right (RR),
A plurality of multiplex nodes such as wheel speed sensors 14 to 17 for detecting the speed of each wheel of the rear left (RL) are connected via a multiplex bus 18 composed of a shielded twisted pair cable or the like to form a network. Signals such as speed information are serially multiplexed and transmitted. Among these multiplex nodes, the wheel speed sensors 14 to 17 do not have a calculation or judgment function and communicate with each of the computers 11 to 13.
Nodes subordinate to the computers 11 to 13 transmit signals of wheel speed information to the computers 11 to 13, respectively. The wheel speed information is used for controlling various functions such as an engine, an anti-lock brake, and a transmission. Used. Each of the multiplex nodes is assigned a unique address. For example, each of the computers 11 to 13 for the engine, antilock traction, and transmission has addresses 0 to 2, FR, FL,
Addresses 3 to 6 are assigned to the RR and RL wheel speed sensors 14 to 17, respectively.
When the data is received normally, an ACK signal is returned to a location corresponding to the unique address assigned to the transmission frame. The transmission source multiplex node transmits logic "0" from the beginning unless an abnormality is detected.

FIG. 1 shows a system configuration common to the following embodiments. Each computer 11-1
3 operate independently of each other, each of which transmits the message shown in FIG.
8 In this case, the priority control functions without destroying the message by the procedure of FIG. 14, and the transmission of the low priority message is automatically interrupted, and the transmission of the high priority message is continuously performed. You can continue. Each of the computers 11 to 13 has the ACK management function shown in the conventional example.

The present invention makes it possible to collect data efficiently in such communication between multiple nodes. In this embodiment, the message shown in FIG. When the format is transmitted to the multiplex bus 18, the wheel speed sensors 14 to 17 transmit data to a predetermined data area in the message in a predetermined order, a so-called SD.
The case of the G (Simultaneous Data Gathering) control method will be described based on the transmission procedure of FIG. The message format of the data frame shown in FIG.
The message format is almost the same as the message format shown in FIG. 13, except that the data area is divided in advance so as to correspond to the transmission data of each multiplex node performing data transmission according to the message ID indicating the transmission request. For example, it is known in advance that the antilock traction computer 12 receives the wheel speed signal data of 1 byte from each of the four wheel speed sensors 14 to 17. Is specified as 4 bytes, and the order in which the wheel speed signal data is received is, for example, FR, FL, FL, FL in the same manner as the ACK signal return order.
RR and RL are set in the order of the wheel speed sensors 14 to 17.

Referring to FIG. 3, first, when a wheel speed signal is required to control the driving force and the brake, the antilock traction computer 12 which is a transmission multiplex node requests the multiplex bus 18 to transmit a wheel speed signal. Show
The transmission of the message of FIG. 2 is started by the ID, and then the control data is transmitted to the multiplex bus 18. Anti-lock
Since the traction computer 12 receives the wheel speed signal of 1 byte from each of the wheel speed sensors 14 to 17, the control data is set to 4 bytes.

Wheel speed sensors 14 to 14 which are reception multiplex nodes
17 receives the message ID, recognizes that the transmission of the wheel speed signal has been requested, and starts the preparation for transmitting the requested data. In this case, the transmission code in the data area shown in FIG. 2 is configured by a PWM (pulse width modulation) signal as shown in FIG. 15, similarly to the transmission code in the ACK signal area. In the PWM signal, one logical bit is divided into three phases, a first phase is represented by an active signal level, a third phase is represented by a passive signal level, and a second phase is represented by an active signal level or a passive signal level. By expressing with logic “0” and logic “1”
Constitutes the state. Therefore, in the above data area,
As shown in FIG. 4, the antilock traction computer 12, which is the source of the data frame, continuously sends active signals on the multiplex bus 18 at the first phase of each bit. One of the wheel speed sensors 14 to 17 is provided with a first bit area (data area) assigned to its own station from the transmitted data frame.
The rising edge of the phase is detected, and data is transmitted at least in the second phase in synchronization with the active signal in the first phase. This makes it extremely easy for each multiplex node to synchronize.

Next, the antilock traction computer 12 calculates the transmitted PRI, ID, CONT, the data area into which the transmission data of the own station is inserted, and the error check code based on the data transmitted by the own station. , CR
Generate C code. Also, the antilock traction computer 12 calculates in the data area transmitted by another multiplex node based on the received data,
Codes are generated, and the generated CRC codes are transmitted to the multiplex bus 18.

On the other hand, each of the wheel speed sensors 14 to 17
, ID, CONT, a data area and an error check code transmitted by a multiplex node other than the own station are calculated based on the received data to generate a CRC code. Also,
In the data area where the own station transmits data, calculation is performed based on the transmission data, and a CRC code is generated. Then, each of the wheel speed sensors 14 to 17 compares the generated CRC code with the received CRC code, and when they match, determines that the data transfer has been normally performed and returns an ACK signal. , End the data transmission. If they do not match, each of the wheel speed sensors 14 to 17 determines that an error has occurred in data transmission and reception, and does not return an ACK signal but waits for retransmission of the frame.

When the ACK signals are returned from all the multiplex nodes of the wheel speed sensors 14 to 17, the antilock traction computer 12 determines that the data transmission / reception has been normally performed, and terminates the data transmission. Thereafter, the driving force and the brake are controlled based on the received data. If no ACK signal is returned from any of the multiplex nodes, it is determined that there has been an error in data transfer, and the frame is retransmitted.

Therefore, in this embodiment, the data area of the frame to be transmitted is divided in advance so as to correspond to the transmission data of the main multiplex node and the transmission data of the slave multiplex node which performs data transmission in response to the transmission request. In the data area, data is transmitted from each multiplex node in a predetermined order, and the slave multiplex node generates a CRC code based on the transmission data of its own station, a CRC code generated based on the received data, and a main multiplex node. CRC code generated based on the transmission data of the own station and CR generated based on the received data
Since error checking is performed from the C code, data collection from a plurality of multiple nodes on the network and error checking of these data can be accurately performed.

In this embodiment, the data transmission in which the antilock traction computer 12 and the wheel speed sensors 14 to 17 have a master-slave relationship in function has been described. However, the engine computer 11 or the transmission computer 13 and the wheel speed sensor 14 It is of course possible to give the master-slave relationship to No. 17 to perform the data transmission. Further, in the present embodiment, the multiplex transmission method in which a 1-bit ACK signal is returned from all the receiving nodes at the time of normal reception has been described. However, the present invention is not limited to this. Into an ACK signal area indicated by the encoded address.
The present invention can be applied to a multiplex transmission method for returning a CK signal.

Further, in the present embodiment, an acknowledgment method of transmitting a predetermined signal to the ACK confirmation area when an ACK signal is returned from all registered nodes is used, but the present invention is not limited to this. In the event that normal reception was not possible due to a reception error occurring at any of the connected nodes,
A negative acknowledgment system for transmitting a predetermined signal instead of the ACK signal is also conceivable. That is, a data frame composed of the message format shown in FIG. 5 is used and generated by any one of the receiving-side multiplex nodes of the wheel speed sensors 14 to 17.
If the CRC code is a source multiplex node
If the received multiplex node does not match the CRC code transmitted by the traction computer 12, after the error check, the receiving multiplex node transmits the special code NAK signal longer than the EOD code and shorter than the EOM code to the multiplex bus 1.
8 to urge the source multiplex node to retransmit the frame.

FIG. 6 shows a message format of another embodiment of the data frame used in the negative acknowledgment system. Normally, the NAK signal is composed of a priority code which has priority even if it collides with any code on the multiplex bus. Therefore, for example, when detecting a waveform that does not apply to the logic “0” or “1” during data reception, the receiving multiplexing node sends a NAK on the multiplexing bus even while the source multiplexing node continues transmission. When a signal is sent, a collision occurs and a NAK signal is detected on the multiplex bus. Upon detecting the NAK signal, the transmission source multiplex node detects the collision, activates the current transmission, and starts retransmission of the frame. As a result, in the above-described embodiment, quick recovery from normal data transfer is achieved.

In the above-described SDG control system, the case where the code format of the transmission signal is the PWM system has been described. However, the NRZ (Non Return to Zero) system is also available as the code format of the transmission signal. However, when the above code format is changed to the NRZ method, S
When performing DG control, there are the following problems. That is, in the case of the above-mentioned PWM system, as shown in FIG.
Although the code of logic "1" is continuously transmitted to the data area,
Even if the data overlaps with the data from each receiving-side multiplex node, it finally becomes a signal of the receiving-side multiplex node on the multiplex bus 18 as shown in FIG. At this time, even if the receiving-side multiplex node partially failed, for example, even if the FR wheel speed sensor 14 failed, the frame of the frame was not destroyed only by the signal of the data 1 being "11111111". However, when the code format is set to the NRZ system, a so-called stuff bit rule is used in which, when the same code continues for 5 bits, a code inverted by 1 bit is inserted for synchronization. Therefore, assuming that each divided area of the data area has 8 bits, if a subordinate node fails, a signal is not sent to the data area of this node, so that a stuff bit error occurs and There is a problem that data cannot be received.

Therefore, in the present invention, the code format of the transmission signal is changed to NRZ (Non Return to
An embodiment in which an NRZ code of the (Zero) system is used will be described. In this case, for example, the source multiplex node transmits a special code that breaks the stuff bit rule before the insertion data, and inserts the reception data from each reception-side multiplex node to facilitate synchronization. Thus, synchronized multiplex transmission can be performed. That is, in the embodiment of FIG. 7, the data area uses an NRZ code and the stuff bit rule of inserting an inversion code at the sixth bit when the same code of 5 bits continues, but immediately before the data insertion unit. ,
Violating the stuff bit rule, for example, 6
The insertion of data can be facilitated by the source multiplex node requesting the data issuing a dominant code (special code) of bits.

FIG. 8 shows another embodiment in which an NRZ code is used as a transmission code. In the NRZ method in this case, 5
Using the bit stuff bit rule, the synchronization method is switched between the data regions from the stuff synchronization to the start-stop synchronization without breaking the stuff rule. That is, in the data area, for example, 8 bits are divided into four bits as shown in FIG.
In the data area, a 1-bit dominant signal is transmitted after 5 bits of passive bits are left.

Next, the transmission procedure of this embodiment will be described. First, when a wheel speed signal is required for control, the anti-lock traction computer, which is a source multiplex node, transmits a message as shown in FIG. 8 with an ID indicating a request to transmit a wheel speed signal to a multiplex bus. Start sending. In the four wheel speed sensors of the receiving multi-node,
Upon receiving this message ID, it recognizes that it is a request to transmit a wheel speed sensor signal, and starts preparations for transmitting the requested data.

The antilock traction computer also sends control data to the multiplex bus.
Since it is known that this node receives wheel speed sensor signals each consisting of one byte of data from four nodes, front, rear, left and right, the data length can be specified as 4 bytes. Each wheel speed sensor is pre-FR wheel speed sensor,
If the data is determined to be transmitted in the order of FL wheel speed sensor, RR wheel speed sensor, and RL wheel speed sensor,
The anti-lock traction computer can sequentially acquire data from each wheel speed sensor.

At this time, the antilock traction computer leaves the 5-bit passive area and
Since a bit dominant signal is transmitted, the node requested to transmit data, in this embodiment, each wheel speed sensor, at the rise of a predetermined dominant signal,
Detect and synchronize data area to send data,
Data is transmitted to the first 4 bits of the bit passive area, and the remaining 4 bits of data are transmitted to the 5 bit passive area after the next 1-bit dominant signal. Then, after the next 1-bit dominant signal transmitted from the antilock traction computer, the next wheel speed sensor transmits data in the same manner, and transmission data is sequentially collected.

For this reason, each receiving-side multiplex node can synchronize at the rising edge of a predetermined dominant signal, divide the transmission data of its own station into four bits, and transmit it on the multiplexing bus. If one node of the multiple nodes, for example, the FR wheel speed sensor fails, no data is transmitted from the FR wheel speed sensor in the data 1 area of FIG. 9, but the antilock traction computer has a 5-bit passive. Since the 1-bit dominant signal is transmitted after the signal, communication becomes possible to the end without any stuff bit error. Further, the failure of each receiving-side multiplex node can be determined by not responding to the corresponding ACK bit.

In the present embodiment, the source multiplex node transmits a 5-bit passive + 1-bit dominant signal in the data area, but the present invention does not limit the number of bits of the passive signal and the dominant signal to this. Any configuration that does not break the stuff bit rule may be used. By the way, in the above-described embodiment, only the transmission procedure in the multiplex transmission method has been described. However, when the multiplex transmission method of the present invention is used for controlling the driving force of an actual automobile, it is necessary to increase the control accuracy. is there. For this purpose, it is necessary to keep the sampling time of the data of various sensors and the like collected by the SDG method at the same time. The most preferable method for realizing this concurrency is that each node receives the message ID for SDG of the corresponding transmission request frame, recognizes the transmission request, starts the sampling of the data of the requested sensor, etc. Is transmitted to the data area in the same frame.

However, in this method, the process from the start of sampling to the data transmission must be performed in a close area in one frame, for example, in the CONT area in the frame of FIG. Therefore, there is a problem that this method can be applied only to a node that implements transmission data sampling and communication control with one piece of hardware and that data sampling can be completed at a very high speed.

Therefore, according to the present invention, as shown in the transmission procedure of FIG. 10, a dummy data area of a predetermined length is provided between the CONT and the data area of the transmission request frame, and each area of the CONT and the dummy data is transmitted. A multiplex transmission method for sampling and writing data while the data is being transmitted is provided. In a multiplex node in an actual system, sampling of data necessary for transmission is performed by a control circuit, and communication control is realized by a communication control circuit including an integrated circuit or the like. The message format of the data frame shown in FIG. 10 is the same as the message format shown in FIG. Hereinafter, the message format of the data frame shown in FIGS. 11 and 12 is the same as above.

In FIG. 10, each multiplex node (in this embodiment, FR wheel speed sensor 14, FL wheel speed sensor 1
5, RR wheel speed sensor 16, RL wheel speed sensor 1
In 7), the communication control circuit receives the SDG message ID of the corresponding transmission request frame from the source multiplex node (antilock traction 12), and the control circuit recognizes the transmission request according to the message ID.

When recognizing the transmission request, the control circuit of each multiplex node samples data necessary for transmission from the connected load (sensor) via an analog / digital converter, a pulse number counting circuit, and the like. Then, the control circuit writes the sampled data to a predetermined register or the like in the communication control circuit. The sampling and writing of the data are performed by the CONT of the transmission request frame.
And while each area of dummy data of a predetermined length is transmitted,
This is performed by the control circuit. The dummy data may be any data that can recognize in advance that each multiplex node is a dummy, and its data length is arbitrarily set according to the time required for the control circuit to sample and write data. .

When each of the communication control circuits receives the dummy data, the communication control circuit converts the data written in the register into
The data is sequentially transmitted to a predetermined data area of the transmission request frame. Therefore, in the present embodiment, by providing a dummy data area in accordance with data sampling in the transmission request frame,
When collecting data at the same time, it is also possible to ensure the synchronization of the sampling time of each data at each multiplex node.

The data sampling for controlling the driving force of the automobile is usually performed at a predetermined cycle. Therefore, in the present invention, as shown in the transmission procedure of FIG. 11, after receiving a transmission request frame, multiplex transmission for sampling and writing data to be transmitted in a transmission request frame transmitted to the multiplex bus 18 in the next cycle. Provide a method. FIG.
1, when the communication control circuits of the multiplex nodes 14 to 17 receive the SDG message ID of the transmission request frame transmitted from the transmission source multiplex node, the data in the register (data 11, data 21, Data 31 and data 41) are sequentially transmitted to the data area of the frame. When detecting the end of reception of the frame (reception of EOM), the communication control circuit notifies the control circuit of the end of reception of the frame.

When the control circuit receives the notification, it samples transmission data for a transmission request frame to be transmitted in the next cycle. Then, the control circuit writes the sampled data to a predetermined register in the communication control circuit before the transmission of the transmission request frame in the next cycle.
As described above, when the SDG message ID of the transmission request frame is received, this data is transmitted to the data area of the frame by the communication control circuit.

Therefore, in this embodiment, since the data according to the next transmission request is sampled upon completion of the reception of the previous transmission request frame, it is easy to collect the synchronization data in the frame transmitted in a relatively short cycle. Can be done. Further, in the case of a transmission request frame transmitted at a relatively long period, the above-described transmission method requires a longer time from data sampling to transmission, and the data of the sample becomes older and causes a control delay. There is. In the present invention, as shown in the transmission procedure of FIG. 12, a measure is taken by setting the time from receiving the notification by the SDG message ID to the start of data sampling. That is, in the multiplex transmission method of the present embodiment, for a transmission request frame having a relatively long period or non-periodicity,
At the set timing, sampling and writing of data transmitted in the transmission request frame transmitted in the next cycle are performed.

In FIG. 12, a transmission source multiplex node that requests data transmission transmits activation command data for activating data sampling prior to a transmission request frame, and multiplexes the transmission request frame after T time. The data is transmitted to the bus 18. In the present embodiment, the activation command data is a message ID of a transmission request frame immediately before the frame.

Upon receiving the SDG message ID of the transmission request frame transmitted from the transmission source multiplex node, the communication control circuit of each of the multiplex nodes 14 to 17 sequentially stores the data in the register (not shown) in the data area of the frame. Send out. Further, the communication control circuit is configured to execute the message ID
A predetermined time t after the reception of the message ID, the reception of the message ID is notified to the control circuit. Note that the predetermined time t is longer than the end of the reception of the immediately preceding transmission request frame and the time T
Shall be shorter.

When the control circuit receives the notification, it samples transmission data for a transmission request frame to be transmitted in the next cycle. Then, the control circuit writes the sampled data to a predetermined register in the communication control circuit before the transmission of the transmission request frame in the next cycle.
This data is received by the communication control circuit upon receipt of the message ID of the transmission request frame as described above.
The data is sent to the data area of the frame.

In this embodiment, the start command data is
Although the transmission was performed by the source multiplex node, the present invention is not limited to this, and for example, other multiplex nodes may transmit. In this case, the start command data in the frame format must be transmitted when the multiplex bus 18 is idle. Therefore, in the present embodiment, after a predetermined time from the reception of the start command data, data corresponding to the next transmission request is sampled, so that synchronization data in a frame transmitted at a relatively long cycle is easily collected, Control delay can be prevented.

[0045]

As described above, according to the present invention, a plurality of multiplex nodes are connected to each other via a common multiplex transmission line, and the multiplex nodes mutually transmit data for each frame. In the method, a data area of a transmission request frame transmitted from a predetermined multiplex node is divided into a first data area into which transmission data from the own station is inserted, and the transmission data of each multiplex node performing data transmission in response to the transmission request. Is divided in advance into a second data area into which each is inserted , and the predetermined multiplex node is located in the first data area.
When transmitting a frame, the
In response to this, the matching data in the frame is generated, and the second
In the data area, the reception from the multiplex node
Generate matching data in the frame according to the data
Transmitting, the respective multiplex nodes transmit the divided data area.
The transmission data is transmitted in a predetermined order to the local station data insertion area of the area, and in the local station data insertion area,
Is the reference in the frame according to the transmission data of the own station.
The first and the local station data insertion areas
In the outer second data area, the
Generate matching data in the frame according to the received data
And the predetermined multiplex node
And compare it with the collation data received from the
To determine if the mutual data transfer was successful.
Therefore , data from a plurality of multiplex nodes on the network can be simultaneously collected, and an error check of these data can be accurately performed, thereby increasing the efficiency of data transmission.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a multiplex transmission system for a vehicle using a destructive arbitration type CSMA / CD access system according to the present invention.

FIG. 2 is a diagram showing one embodiment of a message format of a data frame according to the present invention.

FIG. 3 is a diagram showing each state of a data frame for explaining an embodiment of a transmission procedure in the multiplex transmission system according to the present invention.

FIG. 4 is a diagram showing a transmission state of a data area in the data frame shown in FIG. 3;

FIG. 5 is a diagram showing another embodiment of a message format of a data frame according to the present invention.

FIG. 6 is a diagram showing another embodiment of a message format of a data frame according to the present invention.

FIG. 7 is a diagram illustrating each state of a data frame for describing an embodiment of a transmission procedure in a multiplex transmission system according to the present invention when an NRZ code is used as a transmission code.

FIG. 8 is a diagram showing an embodiment of a message format of a data frame according to the present invention when an NRZ code is used as a transmission code.

FIG. 9 is a diagram showing each state of a data frame for explaining another embodiment of a transmission procedure in a multiplex transmission system according to the present invention when an NRZ code is used as a transmission code.

FIG. 10 is a diagram showing each state of a data frame for explaining an embodiment of a transmission procedure in the multiplex transmission system according to the present invention when collecting synchronization data.

FIG. 11 is a diagram showing each state of a data frame for explaining another embodiment of the transmission procedure in the multiplex transmission system according to the present invention when synchronizing data is collected.

FIG. 12 is a diagram showing each state of a data frame for explaining still another embodiment of the transmission procedure in the multiplex transmission system according to the present invention when synchronizing data is collected.

FIG. 13 is a diagram illustrating an example of a message format of a data frame.

FIG. 14 is a diagram showing each state of a data frame for explaining an example of a conventional transmission procedure in a multiplex transmission system.

FIG. 15 is a diagram illustrating a configuration of a PWM signal used as a transmission code of the multiplex transmission system.

[Explanation of symbols]

 11 engine computer 12 anti-lock traction computer 13 transmission computer 14-17 wheel speed sensor 18 multiple bus

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Matsuda 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Inside Furukawa Electric Co., Ltd. (72) Kyosuke Hashimoto 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Inside Electric Industry Co., Ltd. (72) Inventor Seiji Hirano 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Corporation (72) Inventor Hiroaki Sakamoto 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (72) Inventor Koji Umegaki 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Corporation (72) Inventor Osamu Dohei 3-1 Shinchi, Fuchu-cho, Aki County, Hiroshima Prefecture Inside Mazda Corporation (72 ) Inventor Koji Terayama 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Co., Ltd. (56) References JP-A-64-24538 (JP, A) JP-A-63-308433 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H04L 12/28 H04Q 9/00

Claims (9)

(57) [Claims] 1. A multiplexing system comprising a plurality of multiplexing nodes connected to each other via a common multiplexing transmission line, wherein the multiplexing nodes are transmitted from a predetermined multiplexing node in a multiplexing transmission system for transmitting data frame by frame. The data area of the transmission request frame is set to the first field for inserting the transmission data from the own station .
The data area and the various areas that perform data transmission according to the transmission request
Second data for inserting the transmission data of the
Data area, and the predetermined multiplex node
In the data area 1, when transmitting a frame,
The verification data in the frame according to the transmission data of the station
Data in the second data area.
Depending on the data received from the multiplex node,
Generates and transmits collation data, and each of the multiplex nodes determines a local station of the divided data area.
The transmission data is transmitted to the data insertion area in a predetermined order.
And in the local station data insertion area,
Matching data in the frame according to the transmission data of the own station
Is generated, and a second area other than the first and local station data insertion areas is generated.
In the data area of
Generating matching data in the frame according to the
It receives collation data generated by its own station from the predetermined multiplex node.
Compares the received collation data with each other and, based on the comparison result,
A multiplex transmission method for determining whether or not the transmission / reception of data has been performed normally . 2. A transmission transmitted from the predetermined multiplex node.
The request frame has an identifier indicating a data transmission request.
The multiplex transmission system according to claim 1, wherein: 3. A transmission acknowledgment signal is included in the transmission request frame.
An area is provided, and each multiplex node transmits and receives data normally.
When performed, the reception acknowledgment signal area is determined in a predetermined order.
Return a reception acknowledgment signal to the
Data is transmitted and received in response to the returned acknowledgment signal.
Determining whether the operation has been performed normally.
Is the multiplex transmission system described in 2. 4. Each of the multiple nodes normally transmits and receives data.
Return the unreceivable signal when
The predetermined multiplex node transmits the
Determine whether the data transfer was successful depending on the presence or absence
3. The multiplex transmission system according to claim 1, wherein: 5. A frame transmitted on the multiplex transmission path.
The transmission code shall consist of one logical bit with at least three small logical bits.
The first small logical bit section is divided into predetermined
In one signal level, the third small logical bit period is
Signal level and the second small logical bit section
By setting to one signal level or the second signal level
Represent logic "1", "0", and each multiplex node
In synchronization with the first signal level of the first small logical bit section,
5. The method according to claim 1, wherein data is transmitted.
The multiplex transmission method described in any of the above. 6. The transmission method according to claim 1, wherein the predetermined multiplex node is a transmission node to be transmitted.
The data area of the requested frame is
The multiplex node that performs data transmission in response to the transmission request
The number of bits of the stuff bit rule according to the transmission data
The signal is divided in advance with a smaller number of bits, and
In synchronization with the relevant signal from the
Transmitting transmission data to a predetermined area of the area.
The multiplex transmission method according to claim 1. 7. The transmission request frame according to claim 1, wherein
Before proceeding with the identification of the data to be transmitted in response to the transmission request
Contains data specified by the identifier, including an identifier
Each multiplex node receives at least the identifier,
Sampling data to be transmitted to the data area.
The method according to any one of claims 1 to 6, wherein
The multiplex transmission method described. 8. The transmission request frame is transmitted at a predetermined cycle.
Transmitted to the multiplex transmission path, and the data is transmitted in response to the transmission request.
Each transmitting multiplex node receives the transmission request frame.
Then, the data of the transmission request frame transmitted in the next cycle
Data transmission is sampled
The method according to any one of claims 1 to 7, wherein
Double transmission method. 9. Prior to transmitting the transmission request frame,
One of the multiple nodes is a sun node.
Transmits a pull activation frame, and in response to the transmission request,
Each multiplexing node that transmits the data
In the data area of the transmission request frame according to the frame
A sampling method characterized by sampling data to be transmitted.
A multiplex transmission method according to any one of claims 1 to 6.
formula.