JP2580146B2 - Vehicle communication control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle communication control device for mutually linking a plurality of control computers mounted on a vehicle or the like.

[Conventional technology]

2. Description of the Related Art Conventionally, vehicles are equipped with a plurality of control computers, and the number of computers is increasing.

Each of these control computers independently controls an object to be controlled in accordance with input signals from sensors and switches and a predetermined control program.

In the case of a vehicle, a plurality of control computers may employ signals from the same sensor as inputs. For example, a vehicle speed signal or an engine speed signal. In the case of a meter control computer, various input signals are input and displayed on the meter panel.
It requires a lot of wiring for signal input from other control computers.

[Problems to be solved by the invention]

As described above, in a vehicle, a plurality of control computers are employed, and the number of wirings thereof is large, and these wirings are increasing. In a vehicle, the mounting space is limited, it is difficult to provide a space for accommodating these wirings, and an increase in weight is also a major problem.

Further, more sophisticated control is required for each control computer, and for this purpose, it is effective to use data from other control computers.

Therefore, it is conceivable that these control computers are mutually data-linked by using a common communication line to reduce wiring. However, in a vehicle, various switches operated by an occupant change their state relatively infrequently, and are often operated only rarely.

Therefore, data that has not changed is communicated. On the other hand, an input signal from a sensor, a control state of a control target by each control computer, and the like frequently change, so that it is desirable to obtain latest data by high-speed communication.

In other words, communicating data having a relatively small change in state is an obstacle to effectively using a common communication line.

The present invention has been made in view of such a problem, and an object of the present invention is to improve the efficiency of use of a common communication line and to enable high-speed data communication in a vehicle communication control device. With the goal.

[Means for solving the problem]

The present invention has a plurality of control computers mounted on a vehicle and controlling a control target based on a predetermined control program, as shown in FIG. A communication system for vehicles, comprising: a communication line to which a plurality of control computers are connected in common and performing data communication; and transmission control means for generating a timing of data communication to the communication line by each of the plurality of control computers. In the control device, among the plurality of control computers, a detection unit that detects a change in predetermined data from the previous transmission timing among a plurality of data that can be transmitted to the communication line; When the change is detected, the counter value is reset, and the first type transmission including all of the plurality of data is performed. When the detecting means does not detect a change in the predetermined data, a counter value is counted up, and when the counter value does not reach a predetermined value, the predetermined value is calculated from the plurality of transmittable data. The second type of transmission data having a reduced data length is created by deleting the data of the counter, and when the detecting means does not detect the predetermined data change continuously a predetermined number of times, and the counter counted up When the value reaches a predetermined value, the counter value is reset, and transmission preparation means for generating the first type transmission data; When a change in data is detected, the first type transmission data is transmitted at the transmission timing, and the detection unit does not detect a change in the predetermined data. And when the counter value has not reached a predetermined value, the second type transmission data is transmitted at the transmission timing, and when the detecting means does not continuously detect a change in the predetermined data a predetermined number of times, and Transmitting means for transmitting the first type transmission data at the transmission timing when the counter value reaches a predetermined value. Technical means of a vehicle communication control device is adopted.

[Action]

 The operation of the configuration of the present invention as described above will be described.

The plurality of control computers 1 connected to the common communication line M2 transmit data at the transmission timing generated by the transmission control means M3, and perform data communication between them.

Detection means M4 provided in these control computers M1
Thereby, a change from the previous transmission timing of the predetermined data among the data that can be transmitted by one control computer M1 is detected. That is, the change of the predetermined data during the transmission timing is detected.

If no change is detected in the predetermined data, the transmission preparation means M5 creates second type transmission data in which the predetermined data has been deleted from the transmittable data, and the second type transmission data is transmitted by the transmission means. Sent by M6.

As described above, if no change in the predetermined data from the previous transmission timing is detected, second-type transmission data having a shorter data length than the first-type transmission data except for the predetermined data is created and transmitted. Will be. Thus, the time required for transmitting the predetermined data is omitted.

In the vehicle communication control device according to the present invention,
When the predetermined data has not changed for the predetermined number of times as described above, the first type transmission data including all the data is transmitted without deleting the predetermined data like the second type transmission data. In this way, the reliability of the data is increased.

〔The invention's effect〕

Thus, in the vehicle communication control device according to the present invention,
The control computer deletes the predetermined data in accordance with a change in predetermined data among the data that can be transmitted, creates second type transmission data having a data length shorter than the first type transmission data, and transmits the second type transmission data. Thus, the occupation time of the communication circuit can be shortened, and the utilization efficiency of the communication line can be improved.

Further, if the predetermined data does not change a predetermined number of times, the first type transmission data including all data is transmitted, so that data reliability can be improved.

Therefore, in the vehicular communication control device according to the present invention, the reliability of the transmission data can be ensured while increasing the utilization efficiency of the communication line.

〔Example〕

Hereinafter, examples to which the present invention is applied will be described. In this embodiment, a plurality of control computers mounted on one vehicle are data-linked via a single communication line.

 First, the configuration of this embodiment will be described with reference to the drawings.

FIG. 2 is a block diagram showing a configuration of a control computer and a communication line arranged in various parts of the vehicle.

100 is a communication line, which consists of a single line. Hereinafter, this is referred to as a serial data line (SDL). The SDL 100 includes a plurality of control computers 110, 120, 130, 14
0,150 is connected. Each of these control computers includes a serial interface 200, and is connected to the SDL 100 via the serial interface 200.

Among these control computers, 110 is a transmission control computer, and 120 is a meter control computer.

The ECU 111 controls, via a drive circuit 112, an electromagnetic valve group 113 for switching an oil passage of an automatic transmission (not shown). For this purpose, the ECU 111 has a well-known CPU, RAM, RO
Built-in M, A / D converter, etc. ECU 111 receives signals from various switches 114 provided on an instrument panel or the like in the vehicle compartment.

The ECU 121 of the meter control computer 120 also has CPU, RAM, R
An OM, an A / D converter and the like are provided, and various kinds of display units 123 for displaying speed, rotation speed, remaining fuel amount and the like are driven via a drive circuit 122. Also, indicator lamp group 1
The 24 lights are turned on / off based on data transmitted from another control computer via the SDL 100.

The ECU of each control computer includes a shift register as a transmission / reception buffer, and the transmission / reception buffer converts between serial data and parallel data.

Next, the operation of the configuration shown in FIG. 2 will be described with reference to the drawings.

In this embodiment, a token bus system is adopted as a communication protocol (protocol), and only the control computer that has obtained the token transmits data.

The format of the data transmitted to the SDL 100 consists of several words as shown in FIG. A header word indicating the transmitted control computer or the like is provided at the head, and a checksum word for determining whether the transmitted data is correct is provided at the tail. Then, a word between them becomes a data word indicating data.

Each control computer determines the presence or absence of its own token from the received header word, and starts its own transmission after a lapse of a predetermined idle time from the time when the transmission of the previous control computer ends.

When the entire system shown in FIG. 2 is started, transmission is started from the control computer having the shortest timer by using timers of different times provided in the respective control computers, and thereafter, tokens are circulated based on the header word.

FIG. 4 shows a flowchart at the time of transmission executed by each control computer. This flowchart is executed when each control computer obtains the token.

In step 401, it is determined whether or not data to be transmitted has changed. This determination is made only for data to be transmitted, such as a switch, which has a relatively small change in state.

If there is a change, steps 402, 403, 40
Through a series of processes of 4, all data words are prepared, and a header word and a check word are added and transmitted.

On the other hand, if there is no change in the data, steps 405 and 40
By a series of processes of 6,407,404, data words excluding data words of switches and the like are prepared and transmitted.

If there is no change in data for N consecutive times, all data words are prepared and transmitted by a series of processes of steps 405, 406, 402, 403, and 404.

FIG. 5 is a flowchart at the time of reception executed by each control computer of this embodiment.

In this flowchart, an interrupt process is triggered by data transfer from a reception buffer including a shift register provided in the ECU as a trigger.

In step 501, it is determined whether or not the data is necessary from the contents of the header word or the like, and the process branches.

In step 502, the received data is stored in the ECU
It is stored at a predetermined address in the RAM.

According to the flowchart described above, when there is no change in data, the data words are reduced, and the time required for transmitting and receiving the reduced data words is reduced.

For example, the transmission control computer 110 shown in FIG. 2 transmits data on the state of the switch as shown in FIG. If there is no change in these switches, this data is transmitted only once in several tokens according to the flowchart shown in FIG. Immediately after the change, this data is immediately transmitted with the next token.

The data shown in FIG.
At 120, the indicator lamp corresponding to each switch is turned on.

FIGS. 7A and 7B are time charts when three control computers A, B, and C are participating in communication. FIG. 11A shows a case where the present invention is not applied, and FIG. 10B shows a case according to this embodiment to which the present invention is applied.

When the present invention is not applied token is coming is cyclically every predetermined period T _1. However, when the present invention is applied, the data length transmitted by another control computer is shortened, and the data length transmitted by itself is also shortened, so that the token obtaining periods T ₂ , T ₃ , and T ₄ are not constant. but rather than at least T ₁ becomes shorter, it is possible to perform faster communication.

In the embodiment described above, the transmission flowchart having the function of deleting data according to the present invention is mounted on all control computers connected to the SDL 100 and constituting the network. However, it may be mounted only on a given control computer.

Further, in this embodiment, the change is detected only for the data of the switch or the like whose change in state is relatively small, but this change may be applied to all the data transmitted by each control computer.

Further, the structure and protocol of the communication line are not limited at all, and can be applied to various types.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the present invention, FIG. 2 is a block diagram showing a configuration of an embodiment to which the present invention is applied, and FIG. 3 is a block diagram of data transmitted by each control computer of the embodiment. FIG. 4 is a flowchart showing an operation at the time of data transmission of one embodiment, FIG. 5 is a flowchart showing an operation at the time of data reception of one embodiment, and FIG. 6 is a transmission data of one embodiment. FIG. 7A and FIG. 7B are time charts showing data transmission timings in one embodiment. M1 control computer, M2 communication line, M3 transmission control means, M4 detection means, M5 transmission preparation means, M6 transmission means, 100 communication line (SDL), 110, 120, 130, 140, 150
... Control computer, 111, 121 ... ECU, 112, 122 ... Drive circuit, 113 ... Solenoid valve group, 114 ... Switch group, 123 ... Display group, 124 ... Indicator lamp group, 200 ... Serial interface.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshihisa Sato 1-1-1, Showa-cho, Kariya-shi Nippondenso Co., Ltd. (72) Inventor Susumu Akiyama 1-1-1, Showa-cho, Kariya-shi Nippondenso Co., Ltd. ( 72) Inventor Takao Saito 1 Toyota Town, Toyota City Toyota Motor Corporation (72) Inventor Tetsuo Tanikawa 1 Toyota Town Toyota City Toyota Motor Corporation (56) References JP 62-36940 JP JP-A-62-36941 (JP, A) JP-A-56-21229 (JP, A) JP-A-54-136244 (JP, A)

Claims (1)

(57) [Claims] 1. A plurality of control computers mounted on a vehicle and controlling an object to be controlled based on a predetermined control program; and a communication line connecting the plurality of control computers in common and performing data communication. A transmission control means for generating a transmission timing of data to the communication line by each of the plurality of control computers, wherein the plurality of control computers can transmit to the communication line. Detecting means for detecting a change in predetermined data from the previous transmission timing among the plurality of data, and when the detecting means detects a change in the predetermined data,
Resetting the counter value, creating the first type transmission data including all of the plurality of data, counting up the counter value when the detecting means does not detect a change in the predetermined data, and setting the counter value to a predetermined value. When the value does not reach the value, the predetermined data is deleted from the plurality of transmittable data to create the second type transmission data having a reduced data length. When no data change is detected, and when the counted-up counter value reaches a predetermined value, the counter value is reset and the first type transmission data is created. When the detection unit detects a change in the predetermined data, of the transmission data created by the unit,
Transmitting the first type transmission data at the transmission timing; and when the detecting means does not detect a change in the predetermined data, and when the counter value does not reach a predetermined value, the second type transmission data is When the detection means does not continuously detect a change in the predetermined data a predetermined number of times, and when the counter value reaches a predetermined value, the first type transmission data is transmitted at the transmission timing. A communication control device for a vehicle, comprising: transmission means for transmitting.