JPH04371036A - Data transmission system - Google Patents

Abstract

PURPOSE:To discriminate between important data and unimportant data even at the time of the occurrence of disturbance by setting only important data out of data transmitted from a transmission station to a maximum data length. CONSTITUTION:When important data is transmitted from a transmission station 1 to a reception station 3, a transmission controller 2 sets a transmission text and outputs it to a data adding device 6 through a data bus 8. The device 6 adds an addition code by a data recognition signal 9 indicating important data and sends data to a transmission line 5 as transmission data having the maximum data length. Meanwhile, transmission data received by the reception station 3 is successively inputted to a reception controller 4 and is inputted to a data length detector 7. The detector 7 reports a data abnormality detection signal 10 to the controller 4 as normalcy. Even if the classification code of unimportant data indicates important data, abnormality is detected because the data length is different from that of important data.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission system for error checking data to be transmitted.

0002

2. Description of the Related Art FIG. 3 is a block diagram showing the configuration of a data transmission system for realizing a conventional data transmission system.
3 is a transmission control device that controls data transmission within the transmission and transmission station 1; 3 is a transmission reception station that receives the transmitted data; and 4 is a reception unit that is located within the transmission and reception station 3 and that controls data reception. It is a transmission path that connects a control device, the transmission transmitting station 1, and the transmission receiving station 3.

FIG. 4 is a diagram showing the structure of data transmitted from the transmission transmitting station 1 to the transmission receiving station 3 via the transmission line 5. In the figure, 11 is the start code of the transmission data, and 12 is the start code of the transmission data. A type code indicating whether the transmission data is important data or non-important data, 13 is transmission information of the transmission data, 14 is an end code of the transmission data, 15
is an error checking code.

Next, the operation will be explained. First, in the transmission transmitting station 1, when data to be transmitted to the transmission receiving station 3 is generated, the transmission data is set in the transmission control device 2, but this is because the data to be transmitted itself is set as the transmission information 13, and this transmission information A type code 12 is added to determine whether the contents of 13 are important or not, and a start code 11 and an end code 14 are added to determine the start and end of transmission data.
Then, an error check code 15, which is the result of predetermined calculations performed on these start code 11, type code 12, transmission information 13, and end code 14, is added to form the transmission text. Further, this transmission text is transmitted from the transmission control device 2 via the transmission line 5 in the order of a start code 11, a type code 12, transmission information 13, an end code 14, and an error check code 15.

On the other hand, at the transmission/reception station 3, the reception control device 4
inputs the start code 11 to start receiving the transmission text, inputs the end code 14, and then inputs the error check code 15, and causes the transmission control device 2 to perform operations on the already input code group. The input error check code 15 is checked to see if it matches the input error check code 15. As a result, if they match, it can be assumed that the data transmission from the transmitting station 1 has been performed normally, and if they do not match, it can be considered that the data has not been transmitted normally.

[0006]

[Problem to be Solved by the Invention] Conventional data transmission systems are configured as described above, so if, for example, a disturbance is input to the transmission path and the type code changes as a result, an error occurs in the error check code. If not detected,
If the content of the transmission data (text) sent from the transmission transmitting station differs from the content received at the transmission receiving station, and furthermore, non-important data changes to important data (starting, stopping the system, etc.), a serious accident may occur. There were issues such as inviting

The present invention was made to solve the above-mentioned problems, and its purpose is to provide a data transmission method that prevents unimportant data from being determined as important data due to changes in content due to external disturbances, etc. do.

[0008]

[Means for Solving the Problems] The data transmission system according to the present invention sets only the data length of important data among the data transmitted from the transmission transmitting station to the maximum length, and the data length of the transmitted data is set at the transmission receiving station. The length of the data determines whether the data is important or non-important.

[0009]

[Operation] The data transmission system of the present invention distinguishes the data length of non-important data and important data and transmits them from the transmitting station, so even if the content changes along with the type code and is not checked for errors, There is no change in data length, which eliminates misidentification of important data.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a data transmission system that implements a data transmission method according to an embodiment of the present invention, and the same or equivalent parts as in the conventional data transmission system (FIG. 3) are denoted by the same reference numerals. The explanation will be omitted.

In the figure, when the data output as a transmission text from the transmission control device 2 (FIG. 4) is important data, additional data 16 is added to the transmission text as shown in FIG. a data addition device that sends out data to
Reference numeral 7 denotes a data length detection device which confirms whether the transmission data received via the transmission path 5 is important data or non-important data, and determines whether the data length matches each of them; data bus, 9 is an important data recognition signal;
10 is a data abnormality detection signal.

Next, the operation will be explained, but here,
First, a case will be described in which non-important data is transmitted from the transmitting station 1 to the receiving station 3. First, when data to be transmitted (non-important data) is generated at the transmission transmitting station 1, the transmission control device 2 transmits a transmission text (type code 1) as shown in FIG.
2 indicates non-important data) and outputs it to the data addition device 6 via the data bus 8 (at this time, the data recognition signal 9 indicates that the data is non-important data). Then, the data addition device 6 recognizes from this data recognition signal 9 that the transmission text outputted by the transmission control device 2 is non-important data, and sends it out to the transmission path 5 as transmission data.

On the other hand, at the transmission/reception station 3, the received transmission data is sequentially input to the reception control device 4 as before (transmission errors are also detected using an error check code).
, is input to the data length detection device 7. The data length detection device 7 determines that the data abnormality detection signal 10 is normal when the input transmission data has the data length of non-important data and the type code 12 indicates non-important data. The reception control device 4 is notified.

Next, a case in which important data is transmitted from the transmitting station 1 to the receiving station 3 will be explained. First, when data to be transmitted (important data) is generated at the transmission transmitting station 1, the transmission control device 2 sets a transmission text (type code 12 indicates important data) as shown in FIG. and outputs it to the data addition device 6 (at this time,
The data recognition signal 9 indicates important data). Then, the data addition device 6 receives this data recognition signal 9.
The transmission control device 2 recognizes that the transmission text outputted is important data, adds an additional code 16 as shown in FIG. 2, and sends it to the transmission line 5 as transmission data of the maximum data length.

On the other hand, at the transmission/reception station 3, the received transmission data is sequentially inputted to the reception control device 4 as before (transmission errors are also detected using the error check code 15), and is inputted to the data length detection device 7. . When the data length of the input transmission data is the maximum data length and the type code 12 indicates important data, the data length detection device 7 determines that the data abnormality detection signal 10 is normal and controls the reception. Notify device 4. In this embodiment, even if the type code 12 of non-important data indicates that it is important data, the data length is not the same as that of important data, so even if no transmission error is detected by error check code 15, it is abnormal. Can be detected.

[0016] In the above embodiment, an example was shown in which the start code 11 etc. were added to the transmission information 13 as the transmission text, but if the transmission information 13 becomes the maximum length, the start code 11 etc. can be omitted. Good too.

Furthermore, in the above embodiment, the case of data transmission between two stations has been described, but there may be three or more transmitting/receiving stations.

[0018]

[Effects of the Invention] As described above, according to the present invention, among the data transmitted from the transmission transmitting station, only the data length of important data is set to the maximum length, and is transmitted separately from the data length of non-important data. This has the effect of preventing the unimportant data from being determined as important data due to changes in the contents of the unimportant data to be transmitted due to disturbances or the like.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a data transmission system that implements a data transmission method according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a configuration of important data used in a data transmission system according to an embodiment of the present invention.

FIG. 3 is a block diagram showing the configuration of a data transmission system that implements a conventional data transmission method.

FIG. 4 is a diagram showing an example of a configuration of transmission data used in a conventional data transmission method.

[Explanation of symbols]

1 Transmission transmitting station 2 Transmission control device 3 Transmission receiving station 4 Reception control device 5 Transmission line 6 Data addition device 7 Data length detection device 8 Data bus 9 Important data recognition signal 10 Data abnormality detection signal

Claims (1)

[Claims] Claim 1: In a transmission system in which the data length is fixed depending on the content of the data to be transmitted, the data length of important data among the data to be transmitted is the maximum length, and the data length of the important data and non-important data is the maximum length. A data transmission method characterized by distinguishing and transmitting.