JPH11163907A - Multiplex transmission device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multiplex transmission device for vehicles that reduces bus occupancy rate of data and efficiently transmits data of plural communication units. SOLUTION: In each of units 1a, 1b and 1c connected to a bus 3, a data transmission control part 23a judges whether or not there is any change in each vehicle data consisting of plural kinds of data and sets in a communication frame in turn updated or data before updating data depending on whether or not there is any judged change in data. An update bit setting part 25a assignes each information for indicating whether or not there is updated data to each data and sets it in the communication frame. A transmission and reception part 21a transmits the communication frame including each set data and each set information for indicating the presence or absence of an update to other communication unit and receives the communication frame from other communication unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle multiplex transmission device, and more particularly to a vehicle multiplex transmission device for reducing the occupation rate of data on a bus.

[0002]

2. Description of the Related Art In a vehicle multiplex transmission apparatus, a plurality of communication units are connected to a bus, and multiplex transmission of vehicle operation information is performed in a serial manner. For example, a communication unit such as an engine system unit, a body system unit, and a meter multiplex unit is connected to the bus, and transmits and receives data to and from other communication units via the bus.

In this case, the speed of data transmitted through the bus is, for example, as low as about 10 kbps and 10 kbps.
Classification can be made at medium speeds of about s to 100 kbps and at high speeds of about 100 to 1 Mbps, and low to high speed data from various parts such as lamps and engines pass through the bus.

[0004] As a known technique of this kind of conventional vehicle multiplex transmission apparatus, for example, there is one disclosed in Japanese Patent Application Laid-Open No. 6-169488. In this vehicle multiplex transmission device, as shown in FIGS. 4A and 4B, the data frame is composed of an SOM indicating the start of a message, and a PR for determining a priority when a plurality of units transmit data at the same time.
I, variable length data areas DATA1 to DATA6, error check code CRC, EOD indicating end of data,
A reception signal area RSP for returning a reception signal in a bit correspondence from all units, an EOM indicating the end of the message,
It consists of an idle area IDL indicating the end of the data frame.

[0005] In FIG. 4A, of the main data,
Data of speedometer and tachometer with short data transfer cycle
Stored in TA1 and DATA2, and the auxiliary data SOM to I
One data frame is configured by adding a DL.

As shown in FIG. 4B, of the main data, data from the fuel gauge having a relatively long data transfer period to the alarm indicator are stored in DATA3 to DATA6, and the auxiliary data SOM to IDL are stored. To form one data frame.

That is, since the former data frame is transferred in a short cycle and the latter data frame is transferred in a relatively long cycle, it is composed of data having a short data transfer cycle and other data having a long data transfer cycle. Data occupancy per unit time is reduced as compared with the conventional method in which data frames are transferred in a short period.

When the units A, B, and C are connected to a bus, for example, a data transfer process from the unit A to the unit B is performed according to a flowchart shown in FIG. Here, it is assumed that oil data, fuel data, and temp data having the same update time are transferred.

First, it is determined whether conditions for transmitting oil data to the unit B are satisfied (step S10).
1). When the oil data changes with respect to the previously transmitted oil data, and when a predetermined update time has elapsed from the time when the previous oil data was transmitted, the transmission condition is satisfied and the updated oil data is added to the unit B. The transmitted oil data frame is transmitted (step S10).
3).

Next, it is determined whether the conditions for transmitting fuel data to the unit B are satisfied (step S10).
5) If the transmission condition is satisfied, a fuel data frame is sent to unit B (step S107).

Further, it is determined whether a condition for transmitting temperature data (temp data) to the unit B is satisfied (step S109). If the transmission condition is satisfied, a temp data frame is transmitted to the unit B (step S109). Step S11
1).

[0012]

However, in the conventional vehicle data transmission, each data having the same update time is transmitted in a separate frame as shown in FIG. For this reason, a large amount of data needs to be transmitted and received, and the occupation rate of the data on the bus increases, so that the data transmission of other units is greatly restricted. Therefore, it has been desired that a plurality of units use the bus efficiently.

An object of the present invention is to provide a vehicle multiplex transmission apparatus capable of efficiently transmitting data of a plurality of communication units by reducing the bus occupation rate of data.

[0014]

The present invention employs the following means in order to solve the above-mentioned problems. The invention according to claim 1 includes a bus and a plurality of communication units connected to the bus, and each of the communication units determines, for each data of the vehicle data including a plurality of types of data, whether or not the data has changed. A data change determining unit that performs updating, or a data setting unit that sequentially sets, in one communication frame, data of update data or pre-update data according to the presence or absence of a change in the data determined by the data change determination unit; An update presence / absence information setting unit that sets each update presence / absence information indicating presence / absence of update of each data in the communication frame in association with each data, and each data set by the data setting unit and the update presence / absence information A transmitting / receiving unit that transmits the communication frame including each update presence / absence information set by the setting unit to another communication unit and receives the communication frame from the other communication unit; Characterized in that it comprises.

According to the present invention, the data change determination section includes:
The presence / absence of the data change is determined for each data, and the data setting unit sequentially sets the update data or the pre-update data according to the presence / absence of the data in one communication frame.

The update presence / absence information setting unit sets each update presence / absence information indicating whether each data is updated in the communication frame in association with each data, and the transmission / reception unit sets each set data and the set data. The communication frame including the updated presence / absence information is transmitted to another communication unit, and the communication frame from the other communication unit is received.

That is, since each data is sequentially set in one communication frame, and each data is transmitted to the destination communication unit via the bus at one time in one communication frame, the frequency of the communication frame on the bus is reduced. Can be reduced.
Therefore, the bus is not unnecessarily occupied. Therefore, the occupancy rate of the data bus is greatly reduced, so that more data can be efficiently transmitted and received between the plurality of communication units.

Further, since each update presence / absence information is set in one communication frame, the receiving side can recognize which data has been updated based on the value of each update presence / absence information.

According to a second aspect of the present invention, there is provided a counter for counting time from the transmission time of previously transmitted data, and the transmission / reception unit is adapted to execute the operation when the time counted by the counter reaches a predetermined update time. , Transmitting the communication frame.

According to the present invention, the counter counts the time from the transmission time of the previously transmitted data, and the transmission / reception section sets the communication frame when the time counted by the counter reaches a predetermined update time. Is transmitted, the communication frame can be transmitted to the destination communication unit for each update time.

The invention according to a third aspect is characterized in that each data set in the one communication frame has substantially the same update time.

According to the present invention, by setting the update time of each data set in one communication frame to be substantially the same time, each data can be transmitted simultaneously in one communication frame at the same update time. .

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vehicle multiplex transmission apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of a vehicle multiplex transmission apparatus according to the present invention. In FIG. 1, respective communication units of a body system unit 1a, a meter system unit 1b, and another unit 1c are connected to a bus 3, and mutually transmit and receive vehicle data between the communication units.

The body unit 1a includes a CPU (central processing unit) 11a, a CAN (control area network) 13a connected to the CPU 11a, and a bus interface (bus I / F) 20a connected to the bus 3. The CAN 13a includes a transmission / reception unit 21a, a memory 22
a, a data transmission control unit 23a having an update bit setting unit 25a, and a counter 27a.

The body system unit 1a is connected to a sensor 31 and an actuator 33 provided at each part of the vehicle for detecting a running state. The actuator 33 is operated by a control signal of the CPU 11a based on a sensor signal from the sensor 31.

Although only one sensor 31 and one actuator 33 are shown in FIG.
Actually, it is assumed that a plurality of sensors 31 and actuators 33 are provided for each.

The body system unit 1a transmits vehicle data such as mileage data, battery voltage data, engine speed data, speed data, oil data, fuel data, temperature data (temp data) detected by the sensor 31 to a bus. Output to 3.

The meter system unit 1b includes a CPU 11b,
It has a CAN 13b connected to the CPU 11b and a bus I / F 20b connected to the bus 3. The CAN 13b includes a transmission / reception unit 21b, a memory 22b, and an update bit setting unit 25b.
And a counter 27b.

The meter system unit 1b includes travel distance data from the body system unit 1a, battery voltage data,
A meter 35 is connected which indicates the engine speed data, speed data, oil data, fuel data, temp data, and the like with hands.

Since the other unit 1c has substantially the same configuration as the body unit 1a and the meter unit 1b, the details are omitted here.

The transmission / reception unit 21a transmits a communication frame including vehicle data to another communication unit other than its own communication unit, and receives a communication frame from another communication unit.

FIG. 3 shows a data format of a communication frame. The communication frame includes a frame ID (frame identification information), a destination address indicating an address of a communication unit of a vehicle data transmission destination, a transmission source address indicating an address of a communication unit of a vehicle data transmission source, an update bit, a data area, and an error. It has a check code CRC. The frame ID is composed of a preamble P for transmitting and synchronizing seven 8-bit string synchronization signals in succession, and a frame start delimiter SFD composed of an 8-bit string with an identification code indicating the start of the frame.

In the data area, for example, oil data, fuel data, temp data, and the like are written in order from the top. The update bit is update presence / absence information indicating whether or not each data in the data area has been updated. When the data has been updated, the update bit is “1”.
If the data has not been updated, the update bit is set to "
0 ".

B ₀ is an update bit for oil data, b ₁ is an update bit for fuel data, and b ₂ is an update bit for temp data.
The memory 22a stores data from the sensor 31 and stores data from another communication unit received by the transmission / reception unit 21a.

The data transmission control section 23a creates a communication frame as shown in FIG. 3 and sends the communication frame to the transmission / reception section 21a, and has an update bit setting section 25a. The counter 27a counts time from the transmission time of previously transmitted data.

The data transmission control unit 23a selects some data having the same update time from a plurality of data to be transmitted, and determines whether or not the data has changed for each of the selected data to be transmitted. Is determined. The update bit setting unit 25a constitutes an update presence / absence information setting unit,
If the data to be transmitted has changed, the update bit indicating the update of the data is set to "1". If the data to be transmitted does not change, the update bit is set to "0".

The data transmission control unit 23a sequentially sets each data having the same update time in the data area of the communication frame. When data to be transmitted changes, the changed data (updated data) is stored in the data area. Data) is set, and if the data to be transmitted does not change, the pre-update data is set in the data area. The transmission / reception unit 21a transmits the communication frame from the data transmission control unit 23a to the bus 3 when the time counted by the counter 27a reaches a predetermined update time.

The transmission / reception unit 21b in the CAN 13b,
The memory 22b, the data transmission control unit 23b, the update bit setting unit 25b, and the counter 27b include a transmission / reception unit 21a in the CAN 13a, a memory 22a, a data transmission control unit 23a,
Since the update bit setting unit 25a and the counter 27a have the same configuration and the same function as the corresponding parts, the description thereof will be omitted.

Next, the operation of the embodiment of the vehicle multiplex transmission apparatus thus configured will be described with reference to the drawings. FIG. 2 shows a flowchart of the operation of the body unit 1a in the vehicle multiplex transmission device according to the embodiment. here,
A case where a communication frame is transmitted from the body system unit 1a to the meter system unit 1b will be described. It is assumed that “0” is set in advance in each update bit in the communication frame for oil data, fuel data, and temp data.

Further, the update time is set short for speed data and engine speed data having a relatively short transfer cycle, and for oil data, fuel data, temp data, lamp data and door opening / closing data having a relatively long transfer cycle. It is assumed that the update time is set long.

First, in the body system unit 1a, the sensor 31 detects speed data, battery voltage data, engine speed data, oil data, fuel data, temp data, and the like. Each of these detected data is stored in the CP in the body unit 1a.
U11a is input to the memory 2 in the CAN 13a.
2a and stored in the data transmission control unit 2 from the memory 22a.
3a.

The data transmission control unit 23a selects data having the same update time from the detected data. For example, oil data, fuel data, and temp data have the same level of update time, so that oil data, fuel data, and temp data are selected.

Then, the data transmission control section 23a determines whether or not the conditions for sending oil data to the meter system unit 1b are satisfied (step S11). That is,
It is determined whether the oil data has changed from the oil data transmitted last time. Step S
The process 11 constitutes a data change determination unit.

When the oil data transmission condition is satisfied,
That is, when the oil data has changed, updating the bit setting unit 25a updates the bit b ₀ for oil data communication frame is set to "1" (step S1
3). Note that, in step S11, when the transmission condition of the oil data is not satisfied, the update bit b ₀ "
The process proceeds to step S15 without setting it to "1".

Next, it is determined whether a condition for transmitting fuel data to the meter system unit 1b is satisfied (step S15). When the transmission condition of the fuel data is satisfied, the update bit setting unit 25a updates the bit b ₁ for fuel data communication frame is set to "1" (step S17). Incidentally, in step S15, when the transmission condition of the fuel data is not satisfied, step S without set to "1" to update bit b ₁
Proceed to step 19.

Further, it is determined whether or not the condition for transmitting the temp data to the meter system unit 1b is satisfied (step S19). When the transmission condition of the balance data is satisfied, the update bit setting unit 25a updates the bit b ₂ for the balance data of the communication frame is set to "1" (step S21). Incidentally, in step S19, when the transmission condition of the balance data is not satisfied, the update bit b ₂ without setting the "1", the process proceeds to step S23.

Then, it is determined whether or not the time counted by the counter 27a has reached a predetermined update time (step S23). When the counted time reaches the update time, the data transmission control unit 23a sets oil data, fuel data, and temp data having the same update time in order from the beginning in the data area of the communication frame (step S25). . The processing in step S25 constitutes a data setting unit.

In this case, when the data to be transmitted changes, the updated data is written in the data area, and when the data to be transmitted does not change, the data before the change is written in the data area.

Then, the transmission / reception unit 21a transmits the communication frame from the data transmission control unit 23a to the meter unit 1b via the bus I / F 20a and the bus 3 (step S27).

As described above, each data having the same update time is sequentially written into the data area of the same communication frame, and each data is transmitted to the destination communication unit via the bus 3 at a time in one communication frame. Therefore, the frequency of communication frames on the bus 3 can be reduced. Therefore, the bus is not unnecessarily occupied. Therefore, the occupancy rate of the data bus 3 is greatly reduced, so that more data can be efficiently transmitted and received between a plurality of communication units.

Further, since the value of each update bit is written in the same communication frame, the receiving side can recognize which data has been updated based on the value of each update bit. For example, the update bit b ₀ and the update bit b ₁ are set to “1” and the update bit b
_If " ₂ " is set to "0", it is understood that the oil data and the fuel data have been updated and the temp data has not been updated.

By setting the update time of each data set in one communication frame to be substantially the same time, each data can be transmitted simultaneously in one communication frame at the same update time.

The present invention is not limited to the embodiment. In the embodiment, the communication frame is transferred from the body unit 1a to the meter unit 1b.
On the contrary, the present invention can be applied to a case where a communication frame is transferred from the meter system unit 1b to the body system unit 1a, or to transmission and reception between other units.

In the embodiment, oil data, fuel data, and temp data having a relatively long update time have been described. However, the present invention is applicable to, for example, speed data and engine speed data having a short update time. Can be.

Further, the form of the network is not limited to the network form described in the embodiment, but may be a token passing system in which each unit connected to the bus sequentially obtains a transmission right (priority). Or other network forms.

[0056]

According to the present invention, the data change judging section
The data setting unit determines the presence or absence of a change in the data for each data, and the data setting unit sequentially sets each data of the update data or the pre-update data according to the presence or absence of the change in one communication frame, and determines whether or not the data is updated. The information setting unit sets each update presence / absence information indicating whether each data has been updated in the communication frame in association with each data, and the transmission / reception unit includes each set data and each set update presence / absence information A communication frame is transmitted to another communication unit, and a communication frame from another communication unit is received.

That is, each data is sequentially set in one communication frame, and each data is transmitted to the destination communication unit via the bus at a time in one communication frame. Therefore, the frequency of the communication frame on the bus is reduced. Can be reduced.
Therefore, the bus is not unnecessarily occupied.

Accordingly, the occupation rate of the data bus is greatly reduced, so that more data can be efficiently transmitted and received between a plurality of communication units. Also, since each update presence / absence information is set in one communication frame, the receiving side can recognize which data has been updated based on the value of each update presence / absence information.

The counter counts the time from the transmission time of the previously transmitted data, and the transmission / reception unit transmits a communication frame when the time counted by the counter reaches a predetermined update time. The communication frame can be transmitted to the destination communication unit for each update time.

Further, by setting the update time of each data set in one communication frame to be substantially the same time, each data can be transmitted simultaneously in one communication frame at the same update time.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram showing an embodiment of a vehicle multiplex transmission device of the present invention.

FIG. 2 is a flowchart showing an operation of a body unit in the embodiment.

FIG. 3 is a diagram showing a data format of a communication frame.

FIG. 4 is a diagram illustrating an example of a data frame of a conventional vehicle multiplex transmission device.

FIG. 5 is a flowchart showing an operation of another example of the conventional vehicle multiplex transmission device.

[Explanation of symbols]

 1a Body system unit 1b Meter system unit 1c Other unit 3 Bus 11a, 11b CPU 13a, 13b CAN 20a, 20b Bus I / F 21a, 21b Transmission / reception unit 22a, 22b Memory 23a, 23b Data transmission control unit 25a, 25b Update bit Setting section 27a, 27b Counter 31 Sensor 33 Actuator 35 Meter

Claims (3)

[Claims] 1. A vehicle comprising: a bus; and a plurality of communication units connected to the bus, wherein each communication unit determines, for each data of vehicle data including a plurality of types of data, whether there is a change in the data. A change determination unit; a data setting unit configured to sequentially set, in one communication frame, data of update data or pre-update data according to the presence or absence of a change in the data determined by the data change determination unit; An update presence / absence information setting unit that sets each update presence / absence information indicating presence / absence of data update in the communication frame in association with each data, and each data set by the data setting unit and the update presence / absence information setting unit A transmission / reception unit that transmits the communication frame including the update presence / absence information set in another communication unit, and receives the communication frame from the other communication unit, Vehicle multiplex transmission apparatus, characterized in that it comprises. 2. A transmission / reception unit, comprising: a counter that counts time from a transmission time of previously transmitted data; wherein the transmission / reception unit transmits the communication frame when a time counted by the counter reaches a predetermined update time. The vehicle multiplex transmission device according to claim 1, wherein the transmission is performed. 3. The vehicle multiplex transmission apparatus according to claim 2, wherein the update time of each data set in the one communication frame is substantially the same.