JPS6236941A - Data communication equipment in automobile - Google Patents

Abstract

PURPOSE:To attain high speed communication at low cost as required by adopting a multi-protocol having two kinds (synchronizing/asynchronizing) of transmission protocol for a central unit and a terminal requiring high speed communication only. CONSTITUTION:In exchanging a message between the central unit 20 and terminal units 40, n0 requiring no high speed communication, a multi-protocol serial communication interface 23 of the unit 20 is set to the asynchronizing communication mode. Then data transmission is executed between the units 40 and n0 by using the asynchronizing transmission protocol. In exchanging a message between the unit 20 and a terminal unit 30 and requiring high speed communication, a multi-protocol serial communication interface 33 between the interface 23 and the unit 30 is set to the synchronizing communication mode. In adopting the multi-protocal for the unit 30 only requiring high speed communication in this way, high speed communication is applied with low cost as required.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a data communication device that mutually transmits digital data between a plurality of devices in an automobile.

[Conventional technology]

As a conventional device of this type, a block diagram is shown in Fig. 3.
There is a wire half-duplex serial communication method, and the transmission protocol is asynchronous when high-speed communication is not required, that is, when the communication speed is approximately several tens of kbps or less, and synchronous when high-speed communication is required. The formula is used.

In the figure, 10 is a transmission/reception data transmission path consisting of one bus for bidirectionally transmitting digital data between devices, and 20 is a CRT and key switch for centrally controlling and centrally displaying multiple devices. In this central unit 20, 21 is an asynchronous (synchronous) serial communication interface such as R3-232C that interfaces with the data transmission line 10 for sending and receiving, and 22 is a serial communication interface 21. This is a communication control means composed of a microcomputer, etc. that controls the communication.

Further, 30 is a first terminal unit that performs data communication with the central unit 2o, and is, for example, a device such as an air conditioner controller or a car stereo system. In this first terminal unit 30, 31 is an asynchronous (synchronous) serial communication interface that interfaces with the transmitting/receiving data transmission path IO, and 32 is a communication control means that controls the serial communication interface 31.

40 and no are respectively the second. The Mth terminal unit is specifically a device similar to the first terminal unit 30. 41. nl is the second. Mth terminal unit 40. Asynchronous (synchronous) serial communication interface in no, 42. n2 are serial communication interfaces 41 . This is a communication control means that controls nl.

Next, the operation will be explained. First, from the central unit 20 to the terminal units 30 to n.

A case in which a message is transferred to a specific one of them will be explained. Here, the message consists of one or more frames, each frame consisting of multiple bytes of data.

When the transmission protocol is asynchronous, the terminal unit identification address code (identification code) at the beginning, followed by the number of transferred data bytes,
Transfer data including command parameters, etc., and a norm consisting of an error check coat are serially sent from the serial communication interface 21 to the transmitting/receiving data transmission line 10 under the control of the communication control means 22. do.

In addition, if the transmission protocol is a synchronous type such as B I 5YNC, the synchronization code (2 characters) for frame synchronization is placed at the beginning, followed by the terminal unit identification address code, number of transfer data bytes, command parameters, etc. Each frame consisting of the transferred data and an error check code is sent from the communication interface 21 to the sending/receiving data transmission line 10 under the control of the communication control means 22.

Furthermore, when transferring a common message from the central unit 20 to all the terminal units 30 to 30 at the same time, in both asynchronous and synchronous cases, the terminal unit 30 to Use a special code that is common to all nos.

On the other hand, the communication procedure when transferring messages from each terminal unit 30 to no. to sentinel unit 20 is as follows.
Both the asynchronous type and the synchronous type are almost the same as the case of transferring from the central unit 20 to each terminal unit 30 to no, and the terminal unit identification address code is a code representing the terminal unit from which the message is sent.

[Problem that the invention seeks to solve]

Conventional in-vehicle data communication devices are configured as described above, so if high-speed communication with a communication speed of several tens of kbps or more is required for some of the terminal units 30 to 30, serial communication using an asynchronous transmission protocol is required. For terminal units that cannot use a communication interface and must use a relatively expensive synchronous serial communication interface, and conversely do not require high-speed communication,
There was a problem that the high-speed communication function was wasted.

This invention was made to solve the above problems, and a part of the terminal unit has a communication speed of several tens of thousands.
To provide an in-vehicle data communication device that enables high-speed communication without using a relatively expensive synchronous serial communication interface even when high-speed communication of 0 kbps or more is required.

[Means for solving problems]

The in-vehicle data communication device according to the present invention has a multi-protocol serial communication interface between the terminal unit and the central unit that requires high-speed communication, which includes two types of transmission protocols: an asynchronous type and a synchronous type.
This is an asynchronous serial communication interface for the terminal unit that does not require high-speed communication.

[Effect]

In this invention, when high-speed communication is required between a terminal unit and a central unit that require high-speed communication, high-speed communication is possible by performing communication using a synchronous transmission protocol, and high-speed communication is not necessary. In this case, communication is performed using an asynchronous transmission protocol.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the block diagram shown in the figure, IO is a transmission/reception data transmission path consisting of one bus for bidirectionally transmitting data between each device, and 20 is a control display system that performs centralized control and centralized display of multiple devices. It is a central unit for In this central unit 20, 23 is a multi-protocol serial communication interface that is equipped with two types of transmission protocols, an asynchronous type and a synchronous type (B I 5YNC), which interface with the data transmission line IO for sending and receiving, and can be switched by hardware or software. , 22 is communication control means for controlling the multi-protocol serial communication interface 23.

Further, 30 is a terminal unit that needs to perform high-speed data communication with the central unit 20, and is, for example, a large-capacity storage device such as a floppy disk drive or a hard disk. In this terminal unit 30, 33 is a multi-protocol serial communication interface equipped with two types of transmission protocols, an asynchronous type and a synchronous type (BI5YNC), which interfaces with the data transmission path 10 for sending and receiving, and 32 is a multi-protocol serial communication interface. It is a communication control means that controls the interface 33.

40 and nO are terminal units that do not require high-speed communication, such as devices such as air conditioner controllers and car stereo systems. 43°n3 are each data unit 40. An asynchronous serial communication interface 42°n2 interfaces with the transmitting/receiving data transmission line 10 at no, and communication control means controls an asynchronous serial communication interface 43°n3 at the terminal unit 401nO.

Next, the operation will be explained.

First, a central unit 20 and a terminal unit 40 that does not require high-speed transmission. When exchanging messages with the terminal unit 40.nO, the multi-protocol serial communication interface 23 of the central unit 20 is first set to the asynchronous communication mode by the communication control means 22, and then the terminal unit 40. Data is transmitted using an asynchronous transmission protocol with no. At this time, the communication procedure is the same as in the case of a conventional asynchronous system.

Next, when exchanging messages between the central unit 20 and the terminal unit 30 that requires high-speed communication, first, when high-speed communication is not required, the multiprotocol serial communication interface 23 of the central unit 20 and the multiprotocol serial communication interface 33 of the terminal unit 30, respectively.
The asynchronous communication mode is set under the control of the communication control means 22.32, and data transmission is performed mutually using an asynchronous transmission protocol. At this time, of course, Central Unisoto 20,
Terminal unit 40 that does not require high-speed communication. no
Data transmission is possible with both.

On the other hand, when high-speed communication is required, the multi-protocol serial communication interface 2 of the central unit 20
3 and terminal unit 30 multiprotocol series i
1 communication interface 33, respectively communication control means 2
2.32, the synchronous communication mode is set, and data is mutually transmitted using the synchronous transmission protocol. Note that the communication procedure at this time is the same as in the case of a conventional synchronous system.

In this embodiment, the serial iJ1 communication interface is used only for the central unit and the terminal unit that requires high-speed communication.Since it is a multi-protocol with two types of transmission protocols, asynchronous and synchronous, some of the terminals If a unit requires high-speed communication, it can be achieved at low cost.

In the above embodiment, both asynchronous and synchronous B
A system with two types of transmission protocols, 5YNC and
Level Date Link Control
r) two types of transmission protocols may be provided.

In this case, when performing high-speed communication between the central unit and the terminal unit, the HDLC hardware uses a frame synchronization flag (code), an end flag (code), an error check code (cyclic redundancy code CRC) ), etc., and also automatically recognizes the address code, which reduces the burden on communication control means and enables more efficient data transmission.

In addition, in the above embodiment, half-two
Although we have shown a model that is equipped with a heavy single-wire bus and transmits data in both directions, the data transmission path for sending and receiving is configured with two buses as shown in the block diagram shown in Figure 2, and each is connected to a central unit. 20, the transmission data transmission path 11
It may also be used as the reception data transmission path 12, in which case the communication method is full duplex, further increasing the transmission capacity.

Furthermore, in the above embodiment, the case where the number of terminal units that require high-speed communication is one has been explained, but even when expanded to two or more, high-speed illumination is naturally possible in the same manner as in the above embodiment.
belief is possible.

〔Effect of the invention〕

As described above, according to the present invention, the serial communication interface between the terminal unit and the central unit, which requires high-speed communication, is made of a multi-protocol type having two types of transmission protocols, an asynchronous type and a synchronous type. Since the serial communication interface of the terminal unit that does not require communication is an asynchronous type, if high-speed communication is required for some terminal units, it is cheaper and faster than configuring the entire system with a synchronous serial communication interface. This has the effect of enabling communication.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an in-vehicle data communication device according to one embodiment of the present invention, FIG. 2 is a block diagram showing another embodiment of the present invention, and FIG. 3 is a block diagram showing a conventional in-vehicle data communication device. It is a block diagram. 10... Data transmission line for sending and receiving, 11... Data transmission line for sending, 12... Data transmission line for receiving, 20...
・Central Unisoto, 22...Communication control means, 23
...Multiprotocol serial communication interface, 3
0... First terminal unit, 32... IL controller, 33... Multi-protocol serial communication interface, 40... Second terminal unit, 4
2... Communication control means, 43... Asynchronous serial communication interface, no... Mth terminal unit, n2... Communication control means, n3... Asynchronous serial communication interface. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (4)

[Claims] (1) A data communication device that mutually transmits digital data between multiple devices in an automobile, including at least one bus for mutually transmitting digital data between a central unit and multiple terminal units. a multi-protocol serial communication interface comprising two types of transmission protocols, an asynchronous type and a synchronous type, for interfacing the central unit and the above-mentioned transmitting/receiving data transmission path, and this multi-protocol serial communication interface. a communication control means for controlling; an asynchronous serial communication interface for interfacing a terminal unit that does not require high-speed communication with the central unit among the plurality of terminal units and the data transmission path for sending and receiving; and the asynchronous serial communication interface; A communication control means for controlling a serial communication interface, and an asynchronous type and a synchronous type for interfacing a terminal unit that requires high-speed communication with the central unit among the plurality of terminal units and the data transmission line for sending and receiving. An in-vehicle data communication device comprising: a multi-protocol serial communication interface having two types of transmission protocols; and communication control means for controlling the multi-protocol serial communication interface. (2) The transmission protocol of the multi-protocol serial communication interface in the central unit and the terminal unit that requires high-speed communication between the central unit and the central unit is two types: an asynchronous type and a BISYNC type. The in-vehicle data communication device according to item 1. (3) The transmission protocol of the multi-protocol serial communication interface in the central unit and the terminal unit which requires high-speed communication between the central unit and the central unit is two types: an asynchronous type and an HDLC type. The in-vehicle data communication device according to item 1. (4) In-vehicle data according to any one of claims 1 to 3, characterized in that the data transmission path for sending and receiving is composed of two buses, one for sending and one for receiving. Communication device.