JPH0511820B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a code independent mode data transmission system for data communication.

〔overview〕

The present invention uses a code-independent mode data transmission method for data communication, in which a DLE code and an STX code are repeated twice at the position indicating the start of the text of the transmitted data in the transmitter.
DLE STX DLE STX code frame,
When the receiver detects this transmission control code (DLE STX) from the received data, it determines that it is the start of text, so even if there is an error in the transmission control code that indicates the start of text in the received data, the transmitted information This is to prevent a code with the same bit pattern as a transmission control code indicating the start of text from being mistakenly determined as the start of text.

[Conventional technology]

FIG. 5 is a block diagram of a transmitter section of a conventional data transmitter. FIG. 6 is a block diagram of a receiving section of a conventional data transmission device. FIG. 7 shows a transmission frame format of a conventional data transmission device. FIG. 8 is a diagram showing code DLE insertion and removal of transmitted and received data in a conventional data transmission device.

The conventional data transmission device, as shown in Fig. 5,
The transmission control circuit 1 includes a DLE STX storage circuit 22, a transmission information storage circuit 3, a DLE ETX storage circuit 5, a block check character (BCC) generation circuit 7,
By controlling the selection circuit 6 and the selection circuit 8, a DLE which is a transmission control extended character code is placed before the information section as shown in the transmission frame format shown in FIG.
(date link ecape) code and a transmission control code (STX) indicating the start of the text of the transmitted data,
After the information part, this DLE code and a transmission control code (ETX) indicating the end of the text are added, and then a block check character (BCC) is added and transmitted. Also, as shown in Figure 8,
The DLE insertion circuit 4 inserts a transmission control code into the transmission information.
When this code contains a code with the same bit pattern as DLE, this code is a transmission control code.
Add a code and send as (DLE DLE).

Further, as shown in FIG. 6, when the DLE STX detection circuit 31 detects a transmission control code (DLE STX) indicating the start of text from the received data, it notifies the reception control circuit 14, and the DLE ETX detection circuit 12 The end of the text of the received data is detected and notified to the reception control circuit 14. DLE removal circuit 13
When receiving consecutive codes DLE in the received information, as shown in FIG. 8, the odd-numbered code DLE is removed and the even-numbered code DLE is used as the information code to output the received information to the received information storage circuit 16. . The reception control circuit 14 transfers the reception information in the reception information storage circuit 16 to the reception information storage circuit 17 when the output result of the block check character verification circuit 15 is correct.

[Problem that the invention seeks to solve]

However, since such conventional data transmission devices use the transmission frame format shown in FIG. 7, at least one of the two transmission control codes (DLE STX) indicating the start of text in the received data is Even when the code is incorrect, the reception control circuit 14 operates by determining the code (DLESTX) in the information section as the start of text, which has the disadvantage that depending on the content of the information section, a missed error frame may occur.

The present invention solves the above-mentioned drawbacks, and even if there is an error in the transmission control code indicating the start of text in the received data, a code with the same bit pattern as the transmission control code indicating the start of text in the transmitted information is replaced with the text. The purpose of the present invention is to provide a data transmission method that does not erroneously determine the start of a process.

[Means for solving problems]

The present invention uses codes including DLE codes and STX codes as transmission control codes, and uses the above-mentioned codes in transmission information.
When a code with the same bit pattern as the DLE code is included, in a data communication system that inserts the above-mentioned DLE code following this code and transmits the frame, the above-mentioned DLE code is inserted before the transmission information section of the frame in the transmitting section. A frame is sent with a code in which the combination of the above STX code and the above STX code is repeated twice, and when the receiver detects the above twice repeated DLE code and STX code from the received data, it is determined that the text starts. It is characterized by

[Effect]

The transmitter transmits a transmission control code (DLE STX) in which DLE and STX are repeated twice at the start position of the text of the transmission data of the frame, and the receiver transmits the transmission control code (DLE STX) from the received data. DLE STX) is detected as the start of text, so even if there is an error in the transmission control code indicating the start of text in the received data, the same bit pattern as the transmission control code indicating the start of text in the transmitted information is detected. The code will not be mistakenly judged as the start of text.

〔Example〕

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

FIG. 1 is a block diagram of a transmitting section of a data transmitting apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram of a receiving section of a data transmission apparatus according to an embodiment of the present invention.

In FIG. 1, the transmitter of the data transmission device is
A transmission control circuit 1 that controls data transmission and stores transmission control codes (DLE STX DLE STX),
a DLE STX DLE STX storage circuit 2 that outputs the transmission control code under the control of the transmission control circuit 1;
a transmission information storage circuit 3 that stores transmission information and outputs the transmission information under the control of the transmission control circuit 1;
Enter this transmission information and enter the transmission control code in the transmission information.
A DLE insertion circuit 4 adds a transmission control code DLE when the same bit pattern as DLE appears and outputs it as (DLE DLE);
A DLE ETX storage circuit is provided, which stores a DLE STX) and outputs the transmission control code under the control of the transmission control circuit 1.

The transmitter of the data transmission device also includes a selection circuit 6 which inputs the output of the DLE insertion circuit 4 and the output of the DLE ETX storage circuit 5, and selects and outputs these outputs under the control of the transmission control circuit 1. A block check character generation circuit 7 receives the output of the circuit 6 to generate a block check character (BCC), and outputs the block check character under the control of the transmission control circuit 1.
and the output of DLE STX DLE STX storage circuit 2,
A selection circuit 8 is provided which inputs the output of the selection circuit 6 and the output of the block check character generation circuit 7, selects these outputs under the control of the transmission control circuit 1, and outputs transmission data.

In FIG. 2, the receiving section of the data transmission device is
Input the received data sent from the transmitter and detect the transmission control code (DLE STX DLE STX)
DLE STX DLE STX detection circuit 11, DLE ETX detection circuit 12 that inputs received data and detects transmission control codes (DLE ETX), receives received data and receives consecutive codes DLE in received information. Then, a DLE removal circuit 13 is provided which removes the odd-numbered code DLE and outputs received information.

In addition, the receiving section of the data transmission device is DLE STX
DLE STX detection circuit 11 detection output and DLE
The detection output of the ETX detection circuit 12 is input to the reception control circuit 14 which receives notification of the start and end of the received data frame, and the output of the DLE removal circuit 13 is input to the reception control circuit 14. A block check character test circuit 15 that tests the character and outputs the test result to the reception control section 14; and a reception information storage that receives the output of the DLE removal circuit 13 and stores this output under the control of the reception control circuit 14. circuit 16
and block check character verification circuit 1
5 is correct, the reception information storage circuit 17 stores the output of the reception information storage circuit 16 under the control of the reception control circuit 14.

The operation of the data transmission device having such a configuration will be explained. FIG. 3 shows a transmission frame format of the data transmission apparatus of the present invention. Figure 4 shows the code DLE of transmitted and received data of the data transmission device of the present invention.
It is a figure which shows the insertion and removal of.

In FIG. 1, the transmission control circuit 1 includes DLE
STX DLE STX storage circuit 2, transmission information storage circuit 3, DLE ETX storage circuit 5, block check character generation circuit 7, selection circuit 6, and selection circuit 8 are controlled to convert the transmission data into the transmission frame format shown in FIG. Make it into a mat and send it out. Further, as shown in FIG. 4, when the same bit pattern as the transmission control code DLE appears in the transmission information, the DLE insertion circuit 4 adds the code DLE to the code (DLE).
DLE).

In FIG. 2, the DLE STX DLE STX detection circuit 11 detects the start of the text from the received data, notifies the reception control circuit 14, and
The ETX detection circuit 12 detects the end of the text of the received data and notifies the reception control circuit 14 of the end.
When the DLE removal circuit 13 receives consecutive codes DLE in the received information, it removes the odd-numbered codes DLE and removes the even-numbered codes DLE as shown in FIG.
is treated as an information code, and the received information is output to the received information storage circuit 16. The reception control circuit 14 transfers the reception information in the reception information storage circuit 16 to the reception information storage circuit 17 when the output result of the block check character verification circuit 15 is correct.

〔Effect of the invention〕

As explained above, in the present invention, a code error occurs in a transmission control code, and the received data in a frame is
Even if there is a DLE STX code, this has the effect of eliminating the possibility of misjudging this code as the start of text.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a transmitting section of a data transmitting apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram of a receiving section of a data transmission device according to an embodiment of the present invention. FIG. 3 shows the transmission format of the data transmission device of the present invention.
FIG. 4 is a diagram showing insertion and removal of DLEs in transmitted and received data of the data transmission apparatus of the present invention. FIG. 5 is a block diagram of a transmitting section of a conventional data transmission device. FIG. 6 is a block diagram of a receiving section of a conventional data transmission device. FIG. 7 shows a transmission frame format of a conventional data transmission device. FIG. 8 is a diagram illustrating insertion and removal of DLE in transmitted and received data in a conventional data transmission device. 1...Transmission control circuit, 2...DLE STX DLE
STX storage circuit, 3... Transmission information storage circuit, 4...
...DLE insertion circuit, 5...DLE ETX storage circuit,
6, 8... Selection circuit, 7... Block check character generation circuit (BCC generation circuit), 11
...DLE STX DLE STX detection circuit, 12...
DLE ETX detection circuit, 13...DLE removal circuit,
14... Reception control circuit 15... Block check character verification circuit (BCC verification circuit), 1
6, 17...Reception information storage circuit, 22...DLE
STX storage circuit, 31...DLE ETX detection circuit.

Claims (1)

[Claims] 1. A code including a DLE code and an STX code is used as a transmission control code, and when a code with the same bit pattern as the above DLE code is included in the transmission information, this code is followed by the above DLE code. In a data communication system that inserts a code and transmits a frame, the transmitting section adds a code in which the combination of the above DLE code and the above STX code is repeated twice before the transmission information section of the frame, and then transmits the frame. , The above is repeated twice from the received data in the receiving section.
A data transmission method characterized by determining that text has started when a DLE code or an STX code is detected.