JPS6159944A - Sequence number check system - Google Patents

Abstract

PURPOSE:To detect quickly a fault of an information frame by comparing a sequence number in a reception confirming signal frame transmitted to an opposite terminal device with as sequence number in an information frame from an opposite terminal device in a communication controller transmitting/ receiving information using an HDLC (high level data link control) procedure. CONSTITUTION:The sequence number of an information frame transmitted next is designated and transmitted from a communication controller to a prescribed terminal device. The sequence number is stored in a prescribed location of a line memory 16 based on an opposite terminal address in an address buffer 11. When the data received from the opposite terminal device is detected to be the information frame next, the sequence number outputted from a control field buffer 22 is compared with the sequence number outputted from a memory 16 based on the address in the information frame by a comparator 15. The comparator 15 generating notice of interruption to a CPU without awaiting an end flag when the result of comparison is dissident.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention provides a communication control device that transmits and receives information frames according to a high-level data link control (hereinafter abbreviated as HDLC) procedure, This paper relates to a sequence number checking method that uses hardware to check and improve the efficiency of transmission line usage.

Data processing systems that time-divisionally receive data from multiple terminals using the HDLC procedure and send out reception confirmation signals have been put into practical use to improve accuracy and speed of data processing.

[Prior Art] FIG. 2 is a block diagram showing the configuration of such a data processing system. In FIG. 2, 1 is the central processing unit CCl2, which is the memory MM, 3 is the line control unit LC14, which is the line correspondence section LA, 5-1, 5-2, ---, the terminals, and 6-
1.6-2-.- indicates a transmission line. Figure 3 is H
3 shows a format for transmitting information according to the DLC procedure. F is a frame identification flag and uses, for example, 01111110'', A is an address field in which the address of the other terminal is entered, and C is a control field in which the data sequence number is entered.

"Data" is an information field into which data of a predetermined length is entered. Fe2 is a frame check sequence and contains a transmission error control code. The processing program and transmission/reception data stored in the memory MM2 are read out by the central processing unit CC1 to control the operation of the line control unit LC3. When receiving data, the data input from the transmission line 6-1, 6-2- is assembled into characters in the line correspondence section LA4, and when the flag pattern F is detected, from then on, every time one character is received, the data is assembled into characters. A processing request is made to At this time, the processing program checks for the presence or absence of an operational error for each character. The data is then stored in memory MM2. When the termination flagged pattern is detected, the central processing unit CCI is notified of the data storage address on the memory MMz and the fact that the termination flag F has been received. Alternatively, the check of the processing program is started after receiving the termination program F.

[Problems to be Solved by the Invention] In the prior art, if a processing program checks each received character, if there is a sequence number error in the received data, it can be detected immediately and the data can be retransmitted to the sending terminal. Requests can be notified. However, when viewed as a system, its processing capacity is small.

Also, check after receiving the termination frame:
The disadvantage was that the line usage efficiency was not high because the timing of detecting sequence number errors was late.

[Means for solving the problems] The means adopted by the present invention to solve the above-mentioned problems are as follows:
A communication control device that transfers information frames while transmitting and receiving data sequence numbers between multiple terminals according to a high-level data link control procedure sends a reception confirmation signal including the sequence number to be transmitted next to a predetermined terminal. In the method of checking the sequence number to be sent, the communication control device includes means for detecting and storing the sequence number corresponding to the destination terminal address in the reception confirmation signal frame, and storage means for receiving the information frame and storing the detected sequence number. and a means for comparing with the sequence number stored in the memory, and when the comparing means outputs a discrepancy, the communication control device notifies the central processing unit of the occurrence of an abnormality.

[Function] The reception confirmation signal specifies the sequence number of the data to be transmitted next from the terminal, and it is memorized. can be detected immediately.

[Embodiment] FIG. 1 shows a block diagram of the configuration of a communication control device as an embodiment of the present invention. In FIG. 1, reference numeral 10 generally indicates a sequence number checking device, and reference numeral 11.21 indicates an Ajeres field read buffer 8BFO.

ABFI, 12.22 is the control field buffer CBFO, CBFI, 13. 23 are data field buffers DBFO, DBFI, 14. 24 is a control unit CNTl.

CNT2.15 is comparator CMP, 16 is line memory LM
shows.

Now, the communication control device notifies a predetermined terminal of the order number of the data to be initially sent, specifying, for example, 000 from 000 to 111 in binary code. This number is used cyclically. The sequence number is designated in buffer DBF013 together with address buffer ABFOII, and stored in memory LM16. It analyzes the contents of the control field buffer CFBO12 and stores only the sequence number in the line memo IJLM16.
NTl 14 works.

Next, when data is transmitted from a predetermined terminal, it is converted into a character signal by the line correspondence section LA and set in the data buffer DBFI23. At the same time as the data is transferred to the memory MM, the address part and control part are determined based on the number of received bytes, and are set in ^BF■ and CBFI21.22, respectively. Next, when it is detected by the bit of CBFI22 that the received frame is an information frame, the line memory LM is read with the address of address buffer ABF I,
Get the sequence number. Comparator CMP compares that value with the sequence number of control field buffer CBFT. When they match, the control unit CNT2 waits for the termination flag reception signal FEND from the line correspondence unit LA, and notifies the central processing unit CC of the normal reception of the data.

If there is a mismatch, the control unit CNT2 immediately notifies an interrupt INT without waiting for the termination flag reception signal FEND, and runs the processing program. Also, the data in the data buffer DBFI is discarded.

When the termination flag is received, the next processing of data from other terminals is started.

In addition, when receiving correctly, the processing program adds 1 to the sequence number and stores it in the line memory. If there is an error, send the same number one more time and store it in memory.

[Effects of the Invention] In this way, according to the present invention, errors in sequence numbers can be quickly detected in received data without reducing the processing capacity of the communication control device, and the terminal is notified of the error. The line does not continue to send invalid data, and the line can be used effectively. Furthermore, the fact that the reception confirmation signal is sent with sequentially changing sequence numbers means that it is always checked that the transmission and reception conditions are good, and the high cost can be maximized.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a communication control device as an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a conventional data processing system, and FIG. 3 is a data transmission format using the HDLC procedure. It is a diagram. 1.--Central processing unit CC2-.-Memory MM3.--
-Line control device LC4・-Line support section LA5-1.5-
2.--Terminal 6-1.6-2.--Transmission line 11.12.--Address field buffer 12.2
2-...Control field buffer 13.23-
・Data field buffer 14.24...-control unit

Claims (1)

[Claims] A communication control device that transfers information frames while transmitting and receiving data sequence numbers between multiple terminals according to a high-level data link control procedure sends a reception confirmation signal including the sequence number to be transmitted next to a predetermined terminal. In the method of checking the sequence number to be sent, the communication control device includes means for detecting and storing the sequence number corresponding to the destination terminal address in the reception confirmation signal frame, and storage means for receiving the information frame and storing the detected sequence number. 1. A sequence number checking method, comprising means for comparing with a sequence number stored in a computer, and when the comparing means outputs a discrepancy, the communication control device notifies a central processing unit of the occurrence of an abnormality.