JPH06290130A - Data communication controller - Google Patents

Abstract

PURPOSE:To provide a data communication controller which can surely confirm transmission of a significant text at a communication procedure level. CONSTITUTION:A reception processing part 120 receives a reception request command 30 that is given to a communication control processor part 12 from a reception request part 110 of an application processing part 11. When the part 120 receives a text from an opposite party station 20, a parity check part 121 checks the presence or absence of errors by using the BCC added to the text. When no error is confirmed, a comparison/check part 122 compares the data (text sequence number) included in the received text designated by the information set in a reception buffer 130 pointed by a reception control block 40 designated by the command 30 with the comparison data set at a subsequent position in the buffer 130. Thus, the justice of contents is checked for the received text, and an affirmative answer is returned to the station 20 when the justice is confirmed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication control device, and more particularly to a control system for confirming delivery of a text during data transfer.

[0002]

2. Description of the Related Art As shown in FIG. 5, a conventional distributed data communication control device 60 includes an application processing section 61 for executing processing (system control) according to an application program, the application processing section 61 and a partner station 70. In general, a communication control processor unit (communication control unit) 62 that executes a communication procedure for transmitting and receiving data to and from is mainly used.

The communication control procedure (data communication phase) in the data communication control device 60 is roughly divided into a link establishment phase 81, a data transfer phase 82, and a link disconnection phase 83, as shown in the sequence chart of FIG. .

After the link is established in the link establishment phase 81, the application processing unit 61 in the data communication control device 60 issues a reception request command 821 to the communication control processor unit 62 in the data transfer phase 82.

Upon receiving the reception request command 821 from the application processing unit 61, the communication control processor unit 62 receives the data (information text) 822 sent from the partner station 70.

Then, the communication control processor unit 62 uses the check data in the predetermined field of the received information text 822 to perform a check process for confirming whether the text is normally delivered (text delivery confirmation), for example, VRC (Vertical Redundancy Check) / LRC (Horizontal Redundancy Check)
Parity check 823 such as / CRC (cyclic redundancy check)
I do.

Then, if there is no error as a result of the above-mentioned parity check (check processing) 823, the communication control processor unit 62 determines that the information text (transmission data) 822 has been normally delivered, and gives an affirmative response to the partner station 70. (ACK) 824 is returned and the information text 82 is returned.
The second main body portion (user data) is passed to the application processing unit 61 as received data 825. On the contrary,
When an error is detected, the communication control processor unit 6
2 returns a negative acknowledgment (NACK) to the partner station 70 as if the information text 822 was not normally delivered (in FIG. 6, only the case where the acknowledgment 824 is returned is shown).

The partner station 70 sends the transmitted information text 82.
2 is an acknowledgment (ACK) 824 to the destination data communication control device 60 (the communication control processor unit 62 therein).
Returned from, the text 822 is discarded as if the text 822 was successfully delivered. The partner station 70 retransmits the text when a negative response (NACK) is returned.

By the way, the size of data transmitted and received between the data communication control device 60 and the partner station 70 is generally limited. Therefore, in order to transmit a data block having a size exceeding the above-mentioned limit, it is necessary to divide the block and transmit it in multiple times. In this case, in the text (user data) sent in each divided data unit, the text generated according to a predetermined rule so that the relationship with the text before and after the text can be understood (to ensure consistency between the texts). Identification data, for example, consecutive numbers (text sequence numbers) are attached.

Therefore, the application processing unit 61 in the data communication control device 60 is connected to the communication control processor unit 62.
Was confirmed to have been successfully delivered by
22) the received data 825 is received.
From the text sequence number set in the specific field in 5, whether the received data 825 has a correct positional relationship with the preceding received data (text), that is, the received data 825 is truly meaningful. Check if it is information. When it is determined that the positional relationship is not correct, the application processing unit 61
The received data 825 is discarded as an error, for example.

On the other hand, in the partner station 70 (transmission side), the communication control processor unit 6 of the data communication control device 60 (reception side).
As a result of confirming that the text 822 has been normally delivered by the parity check by No. 2, the text 822 has already been discarded according to the positive response (ACK) returned from the processor unit 62.

Therefore, the application processing unit 61 of the data communication control device 60 (reception side) judges that the received data 825 is not in the correct positional relationship with the preceding received data (text) as described above. However, the correct text cannot be retransmitted.

[0013]

As described above, in the conventional data communication control device, when the communication control processor receives the information text, the check process (parity check) using the check data of the predetermined field is performed. , If there is no error, it is assumed that the text is normally delivered, and an affirmative response (A
CK) was returned.

However, since it is a communication error that is detected by the above-mentioned check processing (parity check) in the communication control processor section of the receiving side data communication control device,
Even if an invalid text including the relation to the preceding text is sent due to a processing error on the sending side, if there is no communication error, the text is correctly delivered to the sending side. A positive response is returned.

In this case, on the transmitting side, the receiving side (destination)
The corresponding transmission text is discarded in response to the positive response (ACK) from the communication control processor unit of No. 1, so that the application processing unit of the receiving side data communication control device determines whether the content of the reception text is valid. Even if you check if it is not valid, you cannot get valid text.

As described above, in the conventional data communication control device, the delivery confirmation is performed on the received text only by the parity check. Therefore, due to a processing error on the transmission side, the relation with the preceding text is included. If there is no parity error even when illegal text is sent, an acknowledgment (ACK) is returned to the sender as if the text was delivered normally, and the sender responds. The sent text that you
Even if the application processing unit determines that the received text is not valid, there is a problem that the application processing unit (system) can no longer obtain the valid text.

The present invention has been made in consideration of the above circumstances, and an object thereof is to confirm the delivery of a received text at a communication procedure level by using a check data set in a predetermined field of the text. In addition to the check
It is an object of the present invention to provide a data communication control device that can be checked by checking the validity of the contents of the text and can reliably confirm meaningful text delivery.

[0018]

SUMMARY OF THE INVENTION The present invention comprises application processing means for performing processing in accordance with an application program, and communication control means for executing a communication procedure for data transmission / reception between the application processing means and a partner station. In the provided data communication control device, the application processing means communicates a reception request command for directly or indirectly designating a desired check target data portion in the received text and comparison data to be compared with the data at the data portion. Reception request means for issuing to the control means is provided, and the communication control means receives text from the partner station according to the reception request command issued by the reception request means, and checks data in a predetermined field of the received text. First error check according to, and receiving above A second error check is performed by comparing the data at the data to be checked in the received text specified by the request command with the comparison data specified by the command. As a result of both checks, no error is detected It is characterized in that a reception processing means for returning an affirmative response to the partner station is provided only in the case of the above.

[0019]

In the above structure, when the reception request means provided in the application processing means needs the reception request to the communication control means, when the target text is received, the contents of the text are displayed. In order that the validity can be checked by the communication control means (inside the reception processing means), the data portion to be checked (for example, the location where the text sequence number is set) and the comparison data to be compared with the data at the data portion (for example, expected) A reception request command that directly or indirectly specifies the text sequence number) is issued to this communication control means.

Then, the reception processing means provided in the communication control means receives the text sent from the partner station and uses the well-known parity check (first error check) using the check data of the predetermined field of the received text. )
I do. In addition, the reception processing means, among the received text,
The data (for example, the text sequence number) at the check target data portion specified by the reception request command is compared with the comparison data (expected text sequence number) specified by the command, and the received text is determined depending on whether they match. Check whether the content of is valid (second error check).

Then, the reception processing means determines that there is no error as a result of both of the above checks, that is, there is no parity error (communication error), and the content of the designated portion of the text (here, the text sequence number). Only when the application processing means (the reception requesting means therein) has the expected valid content, the received text is confirmed to have been normally delivered, and a positive response is returned to the partner station. With this affirmative response, the partner station (transmission side) discards the corresponding transmission text, but since the validity of the content of the text has already been confirmed, there is no problem.

On the other hand, if it is determined that there is an error in at least one of the checks, the reception processing means returns a negative response to the partner station. This makes it possible to retransmit the corresponding text not only when a parity error is detected but also when it is determined that the content of the text is not valid.

[0023]

1 is a block diagram showing the configuration of a communication system including a data communication control device according to an embodiment of the present invention. In the figure, 10 is a data communication control device, 2
Reference numeral 0 denotes a device (hereinafter referred to as a partner station) that is a communication partner of the data communication control device 10.

The data communication control device 10 mainly includes an application processing section 11 which performs processing according to an application program, and the application processing section 11.
And a partner station 20. The communication control processor unit 12 executes a specified communication procedure for data transmission / reception between the communication station 20 and the partner station 20, and a memory 13 in which the above-mentioned application programs and the like are stored. The application processing unit 11, the communication control processor unit 12 and the memory 13 are connected by a bus 14.

The application processing unit 11 includes the memory 1
Which is realized by a CPU (not shown) that executes an application program or the like stored in FIG. 3, and which issues a reception request command 30 for requesting text reception to the communication control processor section 12. 1
Have 10.

The reception request command 30 indirectly has a reception control block 40 having the structure shown in FIG. 2 in which the contents of instructions relating to text reception are described. In this embodiment, the reception control block 40 is placed on the memory 13 as shown in FIG. 1, and the position (address) on the memory 13 is designated by the reception request command 30. There is.

As shown in FIG. 2, the reception control block 40 includes a reception control block ID 41 indicating that the control block 40 is a reception control block, a reception buffer address 42 indicating a start position of a reception buffer 130 described later,
And information about the size of the reception buffer 130 (reception buffer size).

Referring again to FIG. 1, the communication control processor unit 12 receives the data according to the reception request command 30 (the reception control block 40 designated by the reception request command 30) from the application processing unit 11 (the reception request unit 111 therein). It has a reception processing unit 120 for performing. The reception processing unit 120 is provided with a parity check unit 121 that performs a parity check on the received text and a comparison check unit 122. The comparison check unit 122 compares the data of the position indirectly specified by the reception control block 40 in the received text with the comparison data indirectly specified by the reception control block 40 to detect a match / mismatch. It is supposed to do.

A reception buffer 130 is placed in the memory 13. In the reception buffer 130, as shown in FIG. 2, a reception text storage area 131 for storing (the main part of) the reception text confirmed to be normally delivered.
Is secured. Further, in the start area of the reception buffer 130, for example, information (check start position information) 132 of a predetermined length indicating the start position of the data to be checked (here, the text sequence number) in the received text, and the size of the data ( Information (check size information) 133 having a predetermined length indicating the check size is set. In the area following the area where the check size information 133 is set, comparison data 134 that matches the size indicated by the check size information 133 is set. The received text storage area 131 is secured immediately after the setting area of the comparison data 134. FIG. 3 shows the data communication control device 1.
The format of the text (information text) transmitted and received between 0 and the partner station 20 is shown.

As shown in the figure, the information text includes a control code section 31 indicating the start of the text, a user data header section (text header section) 33 including a text sequence number 32, a user data section 34, and the end of the text. It is composed of a control code portion 35 shown and a block check character (BCC) 36 which is parity information (check data) of text. A block composed of the user data header portion 33 and the user data portion 34 constitutes the body (user data) of the information text. Next, the operation of the embodiment of the present invention will be described with reference to the sequence chart of the communication control procedure (data communication phase) shown in FIG.

First, the application processing unit 11 in the data communication control device 10 performs the communication establishment processing unit 1 in the link establishment phase 51 prior to the start of communication.
A link establishment request command (link establishment request wait command) 511 is issued to the second unit 2 to instruct the establishment of a link with the partner station 20.

As a result, the communication control processor unit 12 is
When the link connection request character (ENQ code) 512 is received from the partner station 20, an affirmative response (ACK) 513 is returned to the partner station 20, and a link establishment completion notification 514 is sent to the application processing unit 11.

When the link establishment completion notice 514 is sent from the communication control processor unit 12 to the application processing unit 11, the link establishment phase 51 is switched to the data transfer phase 52, and the reception request unit 110 in the application processing unit 11 is activated. .

Then, the reception request unit 110 issues the reception request command 30 to the communication control processor unit 12,
Instruct to receive. At this time, the reception requesting unit 110 is positioned on the memory 13 by the command 30 shown in FIG.
A reception control block 40 of the form shown in is prepared in advance. Further, the reception requesting unit 110 receives the reception buffer address 42 and the reception buffer size 4 in the reception control block 40.
Check start position information 132 indicating the position of the text sequence number 32 (in the user data) of the received text and a check indicating the size of the text sequence number 32 in the start area of the reception buffer 130 on the memory 13 designated by 3. The size information 133 is set in advance. Further, the reception request unit 110 has the check start position information 132 and the check size information 13 on the reception buffer 130.
Expected text sequence number 3 in subsequent region of 3
A value of 2 (N is the value of the text sequence number 32 of the information text that was correctly received last time, plus 1)
Is set as the comparison data 134.

When the data (information text) 521 is sent from the partner station 20 in such a state, the reception processing unit 120 in the communication control processor unit 12 transmits the data (information text) 521 in the communication control processor unit 12. On the work memory (not shown) of the. At this time, the parity check unit 121 in the reception processing unit 120 uses the BCC (block check character) 3 of the information text 521.
6 is used to perform a well-known parity check 522.

As a result of the parity check 522 by the parity check unit 121, if a parity error is detected, the communication control processor unit 12 returns a negative acknowledgment (NACK) to the partner station 20. On the other hand, if there is no parity error, the comparison check unit 122 is activated. As a result, the comparison check unit 122 checks the content of the received information text 521 (checks whether the text 521 is truly meaningful and valid data) 5
Do 23. Details of the text content check by the comparison check unit 122 will be described below.

First, the comparison check unit 122 receives the reception request command 3 issued from the reception request unit 110 in the application processing unit 11 to the communication control processor unit 12.
The check start position information 132 and the check size information 1 set in the start area of the reception buffer 130 designated by the reception control block 40 (the reception buffer address 42 and the reception buffer size 43 therein) indicated by 0
From 33, the check target data portion (here, the setting field of the text sequence number 32) in the received information text 522 is recognized, and the data of that portion (text sequence number 32) is taken out from the work memory.

Next, the comparison check unit 122 compares the extracted data (text sequence number 32 in the received information text 522) and the reception buffer 130 with each other.
Comparison data 1 (of the same size as the size indicated by the check size information 133) stored in the area following the check start position information 132 and the check size information 133
34, and the match / mismatch is detected.

If the comparison check unit 122 detects a mismatch, the content of the received information text 521 is not valid (that is, meaningless to the system).
Assuming that an error has been detected, the communication control processor unit 12 returns a negative response (NACK) to the partner station 20. In this case, unlike the conventional case, since the acknowledgment (ACK) is not returned to the partner station 20 at the stage when no parity error is detected, the information text 521 indicates that the partner station 2
It remains in 0, and the text 521 can be retransmitted.

On the other hand, if a match is detected by the comparison check unit 122, the contents of the received information text 521 are valid (that is, meaningful to the system) and there is no error, and the communication control processor unit 12 An acknowledgment (ACK) 524 is returned to the partner station 20.

The communication control processor unit 12 also receives the information text 521, that is, the parity check unit 121.
The information text 521 in which no parity error is detected by the
The main body portion (user data) of the above is passed to the application processing unit 11 as the reception request source as reception data 525. The delivery of the reception data 525 from the communication control processor unit 12 to the application processing unit 11 is performed as follows.

First, when the comparison check unit 122 detects a match, the communication control processor unit 12 first receives the header portion 33 and the user data portion 3 in the received information text 521.
4 is stored in the reception text storage area 131 (following the setting area of the comparison data 134) in the reception buffer 130 as the reception data 525. Then, the communication control processor unit 12 returns a response (reception completion notification) to the reception request command 30 to the application processing unit 11. Then, the application processing unit 11 receives, as the reception data 525, the data stored in the reception text storage area 131 in the reception buffer 130.

When the communication control processor unit 12 returns an affirmative response (ACK) to the partner station 20, the partner station 20 discards the transmission data (information text) 521 held in the partner station 20. . Then, if there is a subsequent information text (information text whose value of the text sequence number 32 is N + 1) on the partner station 20 side, the information text is sent and received between the partner station 20 and the data communication control device 10 as described above. The same is done. If there is no subsequent information text on the partner station 20 side, the partner station 20 sends a control code (EOT) 526 indicating the disconnection of the link to the communication control processor unit 12 in the data communication control device 10, and the link is established. Is disconnected, and the communication control processor unit 1
2 to application processing unit 11 link disconnection notification 5
27 is sent.

In the above embodiment, the comparison check unit 122 performs a check when no error is detected by the parity check by the parity check unit 121, but the present invention is not limited to this. For example, a check by the parity check unit 121 and a check by the comparison check unit 122 are performed in parallel, and an acknowledgment (ACK) is returned only when both have detected no error, and at least one has an error. Alternatively, a negative acknowledgment (NACK) may be returned.

When the application processing unit 11 makes a reception request to the communication control processor unit 12,
The method of designating the desired check target data portion (text sequence number in the embodiment) and the comparison data (as an expected value to be compared with the data in the same portion) in the received text is not limited to the above embodiment. It is also possible to directly specify with the reception request command or the reception control block. Further, as long as the validity of the text content can be confirmed, information other than the text sequence number can be used as the check target.

[0046]

As described above in detail, according to the present invention,
In a data communication control device in which a communication control unit executes a communication procedure for transmitting and receiving data between an application processing unit and a partner station, when a reception request is made from the application processing unit to the communication control unit, a desired text in the received text is received. A reception request command for directly or indirectly designating the data portion to be checked and the comparison data to be compared with the data portion is to be issued from the application processing means to the communication control means, and the communication control means receiving this Then, receiving the text sent from the other station, error check according to the check data of the predetermined field of the received text, and the data of the check target data part specified by the reception request command,
Performs an error check by comparing with the comparison data (expected data) specified by the command, and only when no error is detected as a result of both checks, that is, there is no communication error, and the text is specified. Only when the content of the location is also the legal content expected by the application processing means, the received text is confirmed to have been delivered normally, and an affirmative response is returned to the partner station. You can

(1) The delivery confirmation of the text received in the data transfer phase is surely performed by both the communication error check according to the check data attached to the received text and the correctness check of the content of the received text. You can do it.

(2) Only when no error is detected as a result of both checks on the receiving side, that is, it is not only confirmed that there is no communication error, but the validity of the content of the received text is also confirmed. Only when the confirmation is received, the acknowledgment is returned to the other station, and therefore, even if it is confirmed that there is no communication error, but the validity of the content of the received text is not confirmed, the acknowledgment is not returned. , It is possible to prevent accidental loss of important and valuable data for the system.

(3) Since the content of the received text is confirmed not at the application processing level but at the procedure level (processing by the communication control means), efficient data transmission / reception is possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a communication system including a data communication control device according to an embodiment of the present invention.

FIG. 2 is a reception control block 40 and a block 4 designated by a reception request command 30 in the embodiment.
The figure which shows the data structure of the receiving buffer 130 designated by 0.

3 is a diagram showing a format of information text transmitted and received between the data communication control device 10 and the partner station 20 of FIG.

FIG. 4 is a sequence chart for explaining a communication control procedure in the embodiment.

FIG. 5 is a block diagram showing a configuration of a communication system including a conventional data communication control device.

FIG. 6 is a sequence chart for explaining a conventional communication control procedure.

[Explanation of symbols]

10 ... Data communication control device, 11 ... Application processing unit, 12 ... Communication control processor unit, 13 ... Memory, 2
0 ... Partner station, 30 ... Reception request command, 32 ... Text sequence number, 33 ... User data header section, 34
User data section, 36 ... Block check character (BCC), 40 ... Reception control block, 42 ... Reception buffer address, 43 ... Reception buffer size, 110 ... Reception request section, 120 ... Reception processing section, 121 ... Parity check section, 122 ... Comparison check unit, 130 ... Reception buffer, 131 ... Reception text storage area, 132 ... Check start position information, 133 ... Check size information, 134 ...
comparison data.

Claims (2)

[Claims] 1. A data communication control device comprising: an application processing means for performing processing according to an application program; and a communication control means for executing a communication procedure for data transmission / reception between the application processing means and a partner station, A reception request command for requesting text reception from the application processing means to the communication control means, and a desired check target data portion in the received text and comparison data to be compared with data at the data portion are directly or Reception request means for issuing a reception request command indirectly designated, and text received from the partner station according to the reception request command issued to the communication control means by the reception request means, First error check according to check data It performs a click,
Second by comparing the data of the check target data portion in the reception text specified by the reception request command with the comparison data specified by the command
And a reception processing unit that returns an affirmative response to the partner station only when no error is detected as a result of both checks. 2. The data of the check target data portion designated by the reception request command is added to a divided data unit in accordance with a predetermined rule when dividing one data block and transmitting the divided data in plural times. The reception request means determines the comparison data according to the predetermined rule depending on which position in the data block the divided data corresponds to the divided data. The data communication control device according to claim 1.