JPH04217146A - Data communication equipment - Google Patents

Abstract

PURPOSE:To continuously receive the data without using plural reception buffers by dividing only a reception buffer into the semi-duplex areas. CONSTITUTION:A reception buffer 26 is divided into an area including the buffer addresses 1-n and a semi-duplex area including the buffer addresses (n+1)-2n. Then the buffer 26 stores a received message 1a in the area of the addresses 1-n and then transfers the message 1a to a control microcomputer 3 via a bus 29. If the reception of a message 2a is started while the message 1a is transferred to the microcomputer 3, the message 2a is stored in the area of the addresses (n+1)-2n of the buffer 26. Thus it is possible to prevent the destruction of the data to be transferred to the microcomputer 3 and also to prevent the non-reception of the message 2a.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication device between in-vehicle electronic devices that enables continuous reception processing.

0002

[Prior Art] CSM is used for transmission control of in-vehicle communication networks due to system expandability and ease of transmission control.
A/CD is widely used (e.g. Bosch CAH,
Mazda PALMNET, etc.). Further, the transmission control device is generally implemented as a one-chip IC (hereinafter referred to as a transmission control IC) in order to be easily mounted on various electronic devices.

The configuration of this IC is shown in FIG. This FIG. 1 has the same configuration as a data communication device of the present invention which will be described later, and when explaining the conventional example, this FIG. 1 will be referred to and explained. 1 in FIG. 1 is a transmission line for transmitting messages 1a, 2a, etc., and 3 is a control microcomputer (hereinafter referred to as control microcomputer). The control microcomputer 3 is connected to a reception buffer 26 and a transmission buffer 27 via a bus 29.
is connected to an encoder 23 and a decoder 24 via a framing section 25. Encoder 23 is transceiver 20
The encoder 23 and transceiver 20 constitute a transmitting means. The transmission line 1 is connected to a decoder 24 via a receiver 21. The receiver 21 and the decoder 24 constitute a receiving means. A collision detection circuit 22 is provided between the encoder 23 and the decoder 24.
is connected. The control unit 28 also controls the transmission buffer 2
7. Controls the framing unit 25 and collision detection circuit 25.

In such a data communication device, messages are sent and received on the transmission path using the transmission buffer 27 shown in FIG.
, via the reception buffer 26, but in conventional data communication systems, the configuration of the transmission buffer 27 and reception buffer 26 was provided for one message or multiple messages as shown in FIGS. 3 and 4. . A receive buffer with a half-duplex configuration is provided, which is divided into an area from buffer addresses "1" to "n" (n is a positive integer) and a half-duplex area from buffer addresses "n+1" to "2n". It is something that

Next, the operation will be explained. In the transmission control IC block diagram shown in FIG.
When the data for one message has been stored, a message frame is generated in the framer 25 and sent to the transmission line 1 via the encoder 23 and the transceiver 20.

[0006] Also, at the time of reception, the message from the transmission path 1 is received via the receiver 21 and the decoder 24, and the message frame is decomposed into 1-byte units by the framer 25 and stored in the reception buffer 26. . The control microcomputer 3 reads this via the bus 29 to perform a reception operation from the transmission line 1.

The reception buffer 26 of the transmission control IC 2 is shown in FIG.
and the transmission buffer 27 in FIGS. 4(a) to 4(c).
As shown in the buffers 1 to 27n and the reception buffers 261 to 26n, the configuration is such that transmission and reception are separated and data for one message or multiple messages can be stored in byte units.

[0008]

Problems to be Solved by the Invention In conventional transmission control ICs, continuous reception processing was not possible because the buffer configuration was only for one message each for transmission and reception. Also,
To perform continuous reception processing using the same concept, Figure 4 (a)
) ~ As shown in Figure 4(c), buffers must be prepared for multiple messages, and the transmission control IC2
This led to an increase in circuit scale and cost.

[0009] This invention was made to solve the above-mentioned problems, and an object thereof is to obtain a data communication device that can realize continuous reception processing without using multiple reception buffers. .

0010

[Means for Solving the Problems] A data communication device according to the present invention has an area from buffer addresses "1" to "n" (n is a positive integer) and an area from buffer addresses "n+1" to "2n". A receiving buffer with a half-duplex configuration divided into half-duplex areas is provided.

[0011]

[Operation] The reception buffer in this invention is divided into an area from buffer address "1" to "n" and a half-duplex area from buffer address "n+1" to "2n", so it is continuous. By buffering the second message in the case of reception in the area from "n+1" to "2n", the prevention of reception omissions is achieved without providing a buffer for multiple messages.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a data communication device of the present invention will be described with reference to the drawings. The basic configuration of the data communication device of the present invention is exactly the same as the transmission control IC 2 shown in FIG. It is divided into two areas: an area from buffer addresses "1" to "n" and a half-duplex area from buffer addresses "n+1" to "2n".

Next, the operation will be explained. In explaining this operation, reception when message 1a and message 2a are continuous on transmission path 1 as shown in FIG. 1 will be explained. First, the transmission control IC 2 receives the message 1a via the receiver 21 and the decoder 24, and the framer 25 divides the message into bytes and stores them in the reception buffer 26.

The configuration of the reception buffer 26 is as shown in FIG.
The data is transferred to the control microcomputer 3 via. When the reception of the message 2a starts during the transfer process to the control microcomputer 3, the control microcomputer stores the message 2 in the area from buffer address "n+1" to "2n" of the reception buffer 26 in FIG. This prevents destruction of data transferred to Message 2a and failure to receive message 2a.

If message 2a starts receiving after the contents of message 1a have been transferred to control microcomputer 3,
Similar to the reception process of the message 1a, the message is stored in the area from buffer addresses "1" to "n" of the reception buffer 26 and then transferred to the control microcomputer 3.

Note that the area from buffer addresses "n+1" to "2n" of the reception buffer in FIG. 2 does not necessarily have a byte length for one message. For example, if a message format is used in which the first 3 bytes of the message indicate an address on the network or a control command, if a duplex area is provided from buffer addresses "n+1" to "n+3", continuous Although it is not possible to receive all messages, it is possible to request retransmission because the receiving side can check the addresses, command types, etc. of messages that could not be received. Moreover, when this method is used, the number of buffers can be reduced to only 3 bytes compared to the number of buffers applied to the conventional data communication system shown in FIG. 3 without increasing the buffer capacity.

[0017]

[Effects of the Invention] As described above, according to the present invention, since only the reception buffer of the transmission control IC is configured to be half-duplexed, continuous message reception processing can be easily realized. .

Furthermore, if the half-duplex portion of the receive buffer is kept within a few bytes, it is possible to prevent messages from being dropped during continuous reception with a simpler hardware configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a data communication device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a configuration of a reception buffer in the data communication device of FIG. 1;

FIG. 3 is a diagram illustrating the configuration of a reception buffer and a transmission buffer in a conventional data communication device.

FIG. 4 is a diagram illustrating the configuration of a reception buffer and a transmission buffer in a conventional data communication device.

[Explanation of symbols]

1 Transmission line 2 Transmission control IC 3 Control microcomputer 20 Transceiver 21 Receiver 22 Collision detection circuit 23 Encoder 24 Decoder 25 Framing section 26 Receive buffer 27 Transmission buffer 28 Control section

Claims (1)

[Claims] 1. A transmission buffer that stores transmission data transferred from a control microcomputer; a message frame is generated from the transmission data stored in the transmission buffer; and a message frame is generated from the transmission data stored in the transmission buffer; a framing unit that decomposes the message into bytes; a transmitting unit that sends the message frame generated by the framing unit to the transmission path; and a sending unit that receives the message transmitted to the transmission path and sends it to the framing unit. The area of the receiving means to be transferred and the buffer address are half-duplexed, and the message received by the receiving means and decomposed into bytes by the frame forming section is transferred to the control microcomputer after completion of storage, and the subsequent message is A data communication device comprising a reception buffer for storing a message decomposed into bytes in the frame unit at the time of reception in an adjacent address and then transferring it to the control microcomputer.