JPH0813030B2 - Multiplex device for vehicle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a multiplex transmission device for a vehicle.

(Prior Art) In vehicles, especially in recent automobiles, which are highly electronic,
Since the signal transmission line (signal line) is dedicated for each signal, the number and length of the signal lines for signal transmission tend to be enormous.

For this reason, recently, multiplex transmission has been considered in which multiple types of signals can be transmitted through a common signal line. That is, multiple terminals that perform signal processing for multiplex transmission are provided for switches (sensors) and loads (devices) that are located apart from each other, and each multiplex terminal is connected to a common signal line by a bus system. There is one that is connected (see Japanese Patent Laid-Open No. 57-155603). Among the multiplex transmissions, there is a time slot system (time division system) in which each signal is transmitted in a predetermined cycle. That is, a master terminal for transmitting a reference pulse having a predetermined cycle is connected to a common signal line, and a specific signal is generated for a channel (time) defined for each pulse of the reference pulse. Be associated.

(Problems to be Solved by the Invention) By the way, a vehicle is subject to extremely severe conditions in which the environment in which the vehicle is used often causes considerable vibration or heat. Therefore, when multiplex transmission is to be achieved in a vehicle, it is desirable to fully consider how to ensure reliability for signal transmission. In particular, in the case of multiplex transmission, if the signal line is disconnected or the master terminal fails, all of the plurality of types of signals related to this will be unable to be transmitted.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vehicle multiplex transmission device capable of sufficiently securing the reliability of signal transmission.

(Means and Actions for Solving Problems) In order to achieve the above-mentioned object, in summary, in the present invention, first and second two independent signal lines for a plurality of multiple terminals are provided. And a master terminal for transmitting a reference pulse is connected to each of the first and second signal lines. Specifically, it is arranged in an appropriate place on the vehicle body. A plurality of multiple terminals, a first signal line to which the plurality of multiple terminals are connected by a bus system, and a first master connected to the first signal line and transmitting a first reference pulse of a predetermined cycle A terminal and a second signal line that is provided independently of the first signal line and has the plurality of multiple terminals connected to each other by a bus system; and a second signal line that is connected to the second signal line. Is, it is constituted and a second master terminal for sending a second reference pulse having the same period as the first reference pulse in synchronism with the first master terminal.

With such a configuration, even if one signal line is disconnected or one master terminal fails, the signal can be normally transmitted without any trouble.

Embodiments Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, an automobile A has a first master terminal 11 on the left side and a second master terminal 12 on the right side in the vicinity of a dash panel 3 that defines an engine room 1 and a vehicle room 2. . In addition, in car A,
A multiplex terminal 13 is provided between the master terminals 11 and 12, a multiplex terminal 14 is provided at the front part of the vehicle body, and a multiplex terminal 15 is provided at the rear part of the vehicle body.

Each of the terminals 11 to 15 is connected to the first and second signal lines 21 and 22 independent of each other by a bus method. That is, the first signal line 21 is
Front and rear parts 21a that extend long forward and backward along the left side of the vehicle body
And a pair of front and rear left and right portions 21b and 21c extending from the front end or the rear end of the front and rear portion 21a toward the right side of the vehicle body, and a central left and right portion 21 extending along the dash panel 3 toward the right side of the vehicle body.
It consists of d and. And the first on the front and rear part 21a
The master terminal 11 is connected, the multiple terminals 14 are connected to the front left and right parts, and the multiple terminals 1 are connected to the rear left and right parts 21c.
5 are connected, and the multi-terminal 13 and the second master terminal 12 are connected to the central left and right portions 21d. Similarly to the first signal line 21, the second signal line 22 also includes the respective portions 22a.
22d to 22d, and are arranged so as to be substantially symmetrical with respect to the first signal line 21 as a whole. The first
In the figure, 23 to 25 are connectors for connection in the signal line 21 or 22.

Thus, the first and second two signal lines 21 and 22,
And the first and second two master terminals 11 and 12,
Since they are arranged separately on the left and right sides of the vehicle body, reliable protection of one signal system in the case of a side collision is ensured.

Each of the first and second master terminals 11 and 12 is for transmitting a reference pulse of a predetermined cycle. When both are normal, the reference pulses are synchronized with each other. Send a reference pulse. When one of the master terminals fails and the reference pulse cannot be transmitted, the reference pulse is transmitted only from the normal master terminal.

The multiplex terminal 14 is for, for example, a lamp located at the front of the vehicle body, that is, a headlamp, a small lamp, left and right blinkers, and the like. Further, the multiplex terminal 15 is used for, for example, lamps located at the rear of the vehicle body, that is, tail lamps, back lamps, brake lamps, left and right blinkers, and the like. The multiplex terminal 13 serves as a switch for transmitting signals to lamps corresponding to the multiplex terminals 14 and 15.

With the above configuration, for example, when the driver turns on the headlamp switch, the headlamp switch from the multiplex terminal 13 to the signal lines 21 and 22 at the timing of the channel assigned to this headlamp by the reference pulse. This signal line is sent while a signal (for example, a high signal) meaning that the
The signals sent to 21 and 22 are input to the multiplex terminal 14. Then, the multiplex terminal 14 activates a headlamp drive circuit (not shown), and thereby the headline is turned on.

Now, of one of the first and second signal lines 21 and 22,
It is assumed that the route to the multi-terminal 14 is cut off.
In this case, the signal from the multiplex terminals 13 to 14 is transmitted by the other signal line which is not cut off, and the above-mentioned headlamp is normally lit. Further, even if either one of the first and second master terminals 11 and 12 fails, the multiple terminal is normally operated based on the reference pulse from the other master terminal.
Signal transmission from 13 to 14 is ensured. This applies not only between the multiple terminals 13 and 14 but also between the multiple terminals 13 and 15. The synchronization of the reference pulse between the two master terminals 11 and 12 is performed by both the central left and right portions 21d and 22d.
Even if either 21d or 22d is disconnected, the synchronization between both master terminals 11 and 12 is performed.

Here, in the embodiment, the reference pulse in the first master terminal 11 is set to be positive logic and the second master terminal is set to be negative logic. Then, the multiple terminals 13 to 15 for receiving the reference pulse detect the noise inclusion in the reference pulse by using the positive logic and the negative logic,
Furthermore, it is possible to determine the occurrence of an abnormality in the master terminal. FIG. 2 shows an essential part for performing such signal processing.

In FIG. 2, the first master terminal 11, as shown in FIG. 3 (a), sends a reference pulse with positive logic of a predetermined cycle (partial high in FIG. 2a,
Low state). On the other hand, the second master terminal 12 outputs the reference pulse from the first master terminal 11 to the knot circuit 31.
A negative logic reference pulse is sent out by reversing the output signal (the high and low states shown in FIG. 2B are shown in FIG. 3B).
Shown in).

Both of the reference pulses from both master terminals 11 and 12 are exclusive to the multiple terminals 13 (14 and 15).
It is input to the OR circuit 32, and the signal from this circuit 32 is output to the CPU 33 (determination unit) of the multiplex terminal 13 (14, 15). The reference pulse from the first master terminal 11 is input to the AND circuit 34, and the reference pulse from the second master terminal 12 is input to the AND circuit 34 via the knot circuit 35. Then, the output from the AND circuit 34 is input to the CPU 33.

With the above configuration, both master terminals 11 and 12
When both are normal and no noise is mixed with the reference pulse, the output from the exclusive OR circuit 32 is always high (judgment that both master terminals 11 and 12 are normal and no noise is mixed). The pulse output from the AND circuit 34 at this time is assumed to have the same waveform as that of the first master terminal 11.
The output of 34 is used as the reference pulse used in the multiple terminals 13 (14, 15).

Now, when noise is mixed in with the reference pulse from the first master terminal 11, the waveform of one pulse from the first master terminal 11 becomes incomplete as shown by the broken line in FIG. 3 (a), for example. Think about the case. At this time,
The output from theexclusive OR circuit 32 becomes low at a portion corresponding to noise (determination of noise mixing—see FIG. 3 (c)). Further, consider a case where the second master terminal 12 fails (no output). In this case, since the reference pulse from the first master terminal 11 outputs the reference pulse regardless of the second master terminal 12, the output from the exclusive OR circuit 32 is the same as the reference pulse of the first master terminal 11. Similarly, high and low will be repeated alternately (determination that one master terminal has failed). Furthermore, both master terminals 1
When both 1 and 12 have failed (both have no output), the output from the exclusive OR circuit 32 remains low (determination that both master terminals have failed). In the case where the noise is mixed as described above, for example, the same state as the previous state can be maintained, and when the master terminal fails, an alarm lamp can notify the driver of this failure.

The present invention can be similarly applied to multiplex transmission relating to, for example, a navigation system, engine control, automatic transmission control, and the like.

(Effect of the invention) As is apparent from the above description, the signal line for multiplex transmission and the master terminal are configured as a dual system for each multiplex terminal, so that the reliability of signal transmission is improved. Therefore, it becomes extremely suitable as a vehicle multiplex transmission device.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention. FIG. 2 is a circuit diagram of a main part when one of the reference pulses in the first and second master terminals has positive logic and the other has negative logic. FIG. 3 is a graph showing signal states of respective portions a, b and c in the circuit diagram of FIG. A; Automotive 11: First master terminal 12: Second master terminal 13 to 15: Multiple terminal 21: First signal line 22: Second signal line

Claims (1)

[Claims] 1. A plurality of multi-terminals arranged in proper places on a vehicle body, and a first bus-system connecting the plurality of multi-terminals.
A signal line; a first master terminal connected to the first signal line for transmitting a first reference pulse having a predetermined cycle; and a plurality of multiple terminals provided independently of the first signal line. A second signal line connected by a bus system, and a second signal line connected to the second signal line and having the same period as the first reference pulse in synchronization with the first master terminal.
A second master terminal for transmitting a reference pulse, and a multiplex transmission device for a vehicle, comprising: