JP2007141127A - Communication protocol - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely perform economical and efficient communication in a communication system for transmitting and receiving a message including a large amount of numerical data. <P>SOLUTION: A communication message 11 is constituted of a data column 12 in which the numerical data is included and a header 13 added to the head of the data column 12. The numerical data in the data column 12 is expressed by hexadecimal numerals as it is without converting it into an ASCII code. However, an upper limit value is set to numerical values usable in the data column 12. Then, a specific numerical value, for example, "0xFF" which is the maximum value of 2 byte hexadecimal number, exceeding the upper limit value is continuously specified in the header 13 for four times. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a program for converting a communication message into a format that can be recognized by a computer, and more particularly to a communication protocol suitable for communication of a message including numerical data.

  Conventionally, a communication protocol is known in which a communication source is converted into an ASCII code and a number of ASCII codes are arranged to form a communication message. In transmitting and receiving a message, it is important to recognize the beginning and end of the message. In particular, if the beginning of the message cannot be recognized, it becomes difficult for the computer to decode the received message. In the ASCII code, as shown in FIG. 5, “0x02” is prepared for “STX” attached to the head of the message, and “0x03” is prepared for “ETX” attached to the end of the message. Therefore, the computer can recognize “STX” and “ETX” separately from other characters in the data (numerals: “0x3 *”, English characters: “0x4 *”, “0x5 *”).

  However, in a communication protocol that performs ASCII code conversion, if a hexadecimal value is expressed as 1 byte as it is, the computer may misidentify the hexadecimal value data “0x02” as “STX”. Therefore, in the conventional communication protocol, as shown in FIG. 6, "STX" is added to the head of the message 51, "ETX" is added to the end, and a plurality of numerical data in the data string 52 are respectively set to two ASCII. It has been converted to code. According to this method, for example, the numerical value “0x02” of “data 1” is divided into an ASCII code “0x30” representing “0” and an ASCII code “0x32” representing “2”. Is no longer confused with “data 1”.

Patent Document 1 describes a method of compressing character data by converting a 7-bit ASCII code into a 6-bit shortened code. Patent Document 2 describes a method in which a plurality of character strings are assigned to control codes in ASCII codes and encoded.
JP-A-2005-31868 Japanese Patent Laid-Open No. 11-85459

  However, according to the conventional communication protocol, the numerical data in the data string 52 is converted into two ASCII codes, so that a 2-byte message length is required to send 1-byte numerical data. For this reason, when the message 51 including a large amount of numerical data is transmitted / received, the total length of the telegram 53 becomes unnecessarily long, it takes a long communication time, and a communication fee such as a packet fee increases when using a pay line was there. In addition, when a large amount of numerical data is converted into ASCII code, the burden on the control program becomes heavy, and other processing by the computer becomes slow.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a communication protocol that allows a computer to efficiently communicate messages including numerical data.

  In order to solve the above problems, a communication protocol according to the present invention is a program for converting a communication message into a format that can be recognized by a computer. The communication message is a data string including numerical data and a head of the data string. The numerical value data in the data string is expressed by a hexadecimal value excluding a specific value, and a hexadecimal value indicating the specific value is specified in the header.

Here, the hexadecimal numerical value specified in the header is a specific numerical value that cannot be generated in the data string. In selecting the specific value, preferably, the following means can be employed.
(1) An upper limit is set for a numerical value that can be used in the data string, and a specific value that exceeds the upper limit is specified in the header. In this case, the upper limit value is not limited to a specific numerical value or number of digits, and can be appropriately set according to the application field of the communication protocol, the type of numerical data handled by the protocol, or the like.
(2) A specific value in hexadecimal is specified in the header a plurality of times in succession. The specific value and the number of continuous times are not particularly limited, and can be appropriately selected according to the application field of the communication protocol or the type of numerical data.
(3) For example, “0xFF”, which is the maximum value of a 2-byte hexadecimal number, is used as the specific value, and the numerical value can be specified consecutively in the header a plurality of times.

The present invention can also be implemented by adding the following means to the above communication protocol.
(4) A hexadecimal number serving as an index indicating the message length is added to the data string.
(5) A hexadecimal value indicating a communication error due to noise or the like is added to the data string.

  In the communication protocol of the present invention, numerical data in a data string is represented by hexadecimal numerical values, so that 1-byte numerical data can be transmitted and received as it is without dividing it. For this reason, the message length can be shortened, the communication time can be shortened, the communication cost can be saved, and the conversion process to the ASCII code is not required, thereby reducing the burden on the computer. In addition, since a specific value that cannot occur in the data string is specified in the header, there is no possibility that the computer mistakes numerical data as the header. Therefore, according to the communication protocol of the present invention, there is an effect that economical and efficient communication can be accurately performed particularly when a message including a large amount of numerical data is transmitted.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. As shown in FIG. 1, the communication system 1 of this embodiment is configured such that a plurality of computers 3 connected to a network 2 transmit and receive business messages mainly composed of numerical data using a communication protocol 4. Yes. The communication protocol 4 is implemented in each computer 3 as a part of the communication program, and converts the received message into a format that can be recognized by other programs of the computer 3. Hereinafter, specific functions of the communication protocol 4 will be described in detail with some examples.

  As shown in FIG. 2, in the communication protocol of the first embodiment, the message 11 is composed of a data string 12 in which a large number of numerical data are arranged, and a header 13 positioned at the head of the data string 12. The numerical data of the data string 12 is expressed as a hexadecimal number as it is without being converted into an ASCII code or the like. For example, the “address” of the transmission destination is represented by “0x80”, the “command” is represented by “0xA1”, and the “data 1” is represented by “0x02”. Then, “0xFF”, which is the maximum value of 2-byte hexadecimal numbers, is specified in the header 13.

  However, since many “0xFF” should be included in the data string 12, the communication protocol of the first embodiment sets an upper limit value for a numerical value that can be used in the data string 12 and sets the upper limit value in the header 13. Specify a specific number that exceeds. Specifically, the numerical value in the data string 12 is limited to 8 decimal digits. The decimal number “99,999,999” is the hexadecimal number “0x5F5E0FF”. If this is set as the upper limit value, the maximum value in which “0xFF” appears continuously in the data string 12 is “0x4FFFFFF” (83,886,079), and “FF” continues three times. Therefore, if a specific numerical value in which “FF” continues four times in the header 13, that is, “0xFFFFFFFF” is specified, confusion between the header 13 and numerical data can be avoided.

  In this case, since the actual message 14 requires 4 bytes to display the header 13, the message length of the header 13 is longer than that in the conventional case where the ASCII code “0x02” (see FIG. 6) is specified for “STX”. 4 times. However, according to the communication protocol of the first embodiment, for example, the message length of the data string 12 requiring 200 bytes in the ASCII code is compressed to 100 bytes, which is half. For this reason, the total length of the telegram 14 is shortened by a length corresponding to the subtraction of 96 bytes. Therefore, as the amount of numerical data included in the message 11 increases, the communication time can be shortened, and communication costs such as packet charges can be saved when using a pay line, so that economical and efficient communication can be performed accurately. be able to.

  As shown in FIG. 3, in the communication protocol of the second embodiment, the message 21 is composed of a data string 22 and a header 23, and a cell 25 representing “data length” is provided near the head of the data string 22. The “data length” is data indicating the total length of the data string 22 in bytes, and is represented in the cell 25 by a hexadecimal numerical value as in the other numerical data of the data string 22. For example, when 99 numeric data are included in the data string 22, the “data length” including itself in the cell 25 is represented by “0x64” (decimal number 100).

  In this way, the end of the telegram 24 received by the computer 3 can be correctly recognized based on the data in the cell 25. Therefore, even if the ASCII code “ETX” is omitted from the message 21, there is no problem in communication. Other configurations and operational effects are the same as those of the first embodiment.

  As shown in FIG. 4, in the communication protocol of the third embodiment, the message 31 includes a data string 32 and a header 33, and a cell 35 representing “BCC” is provided at the end of the data string 32. “BCC” is data indicating whether or not a communication error due to noise or the like has occurred in the telegram 34, and is expressed in the cell 35 as a hexadecimal value, as with other numerical data of the data string 32. Here, the calculation result of “BCC” may be “0xFF”. Furthermore, if the “data 99” immediately before “BCC” is “0x4FFFFFF” by chance, “FF” is continued four times together with “BCC”, and the computer 3 may mistake this as the header 33. .

  Therefore, in the communication protocol of the third embodiment, when “BCC” is added, a specific numerical value in which “FF” is continued five times, that is, “0xFFFFFFFFFF” is specified in the header 33. In this way, in the communication system 1 having the error display function by “BCC”, it is possible to reliably avoid the confusion between the header 33 and the numerical data. Other configurations and operational effects are the same as those of the first embodiment.

It is the schematic of the communication system to which the communication protocol of this invention is applied. FIG. 3 is a functional diagram illustrating a communication protocol according to the first embodiment. FIG. 6 is a functional diagram illustrating a communication protocol according to a second embodiment. It is a functional diagram which shows the communication protocol of Example 3. 3 is an ASCII code table used by a conventional communication protocol. It is a functional diagram which shows the conventional communication protocol.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Communication system 2 Network 3 Computer 4 Communication protocol 11, 21, 31 Message 12, 22, 32 Data sequence 13, 23, 33 Header 14, 24, 34 Message

Claims (1)

A program that converts a communication message into a format that can be recognized by a computer. The communication message is composed of a data string that includes numeric data and a header that is added to the beginning of the data string. A communication protocol expressed by a hexadecimal value excluding a specific value, and specifying a hexadecimal value indicating the specific value in a header.

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