JPS60223351A - Communication control system - Google Patents

Abstract

PURPOSE:To decrease the data transfer time with a simple and inexpensive method by allowing a communication control equipment of a communication station to receive plural data packets from an opposite station, checking them and returning one response to the opposite station. CONSTITUTION:A reception station receives the 1st DP and transmits an NACK of retransmission request if any fault exists. When the result of check is OK, a sequence number #n of the reception DP is set and the time count of an ACK transmission timer counter Ta 12 is started, the next DP is received correctly, and when the DP is not the last DP, a Tr being the interval between the Ta and the ACK transmission, the Ta and (Tr-A) are compared, and when the relation of (Tr-A)<Ta=Tr exists, an ACK with the number #n is transmitted, a counter Ta 12 is cleared and when the value Ta is still small, the reception of DP is continued. When the last DP is received, the ACK is transmitted. Moreover, the A (station) is a value smaller than the Tr and is provided so that the Ta during time count does not exceed the Tr value.

Description

Detailed Description of the Invention Technical Field The present invention relates to a communication control method, and particularly to a communication control method for a transfer response line in a data communication system in which a plurality of data processing devices are connected by a communication bus. When data is transferred between stations, each station A, as shown in FIG.

B is an information processing unit l that executes a user's job.

1', communication control units 2, 2' for controlling communication, and memories 3, 3', and a line 4 connects both communication control units. The communication control units 2, 2' of both stations control data transfer according to the communication protocol.

FIG. 2 is a sequence chart of conventional general data transfer.

When data is transferred between stations A and B, the communication control unit 2 of the transmitting station A converts the data from the information processing unit 1 into a sequence number packet structure P(1), and transmits the data from the receiving station B. Then, it waits for reception of ACK (response) #l in response. If the received ACK#] is checked, the D of the sequence number obtained by adding 1 to the above DP(1)
Send P(2). However, if the check is abnormal, the DP (1) is retransmitted. By repeating such operations, all data from the information processing section 1 is transferred to the information processing section 1' of the receiving station B through the line 4. However, as system processing speeds up and the amount of communication data increases, the IACK transfer method for one data packet has the disadvantage that the transfer time becomes longer.

Purpose The purpose of the present invention is to provide a communication control method that can improve such conventional drawbacks and shorten data transfer time using a simple and inexpensive method without using a special communication protocol. .

composition Hereinafter, the configuration of the present invention will be explained using examples.

As a first embodiment of the present invention, a method using a timer will be explained with reference to FIGS. 3 to 5.

FIG. 3 is a data transfer sequence chart 1 to 1 showing the first embodiment of the present invention, FIG. 4 is an operation flow chart 1 to the receiving station in FIG. 3, and FIG. 5 is an internal memory It is a figure showing each area of.

D P (1) to (6) in FIG. 3 are sequence number data packets sent by the transmitting station, and the first D
NACK #4 indicates that P(4) has not reached the receiving station.
It is then retransmitted from DP (4).

At the receiving station, as shown in FIG.
The CK sending timer counter Ta12 and the sequence number #n13 of the received DP are cleared (step 41), the first DP is received (step 42), and if there is an abnormality, a NACK for retransmission request is sent (step 45). If the check is OK, set the sequence number #n of the received DP and start timing the ACK sending timer counter Ta12 (step 44).

If the next DP is correctly received (step 46.41), but it is not the last DP (step 48), Ta is compared with Tr, which is the interval between ACK transmissions, and Ta is compared with (Tr − a ) ( Step 50.51). The value of Ta is (T
r − a ) < Ta : When in Tr,
Step 52: Send ACK with sequence number 4
), clear the ACK sending timer counter and Ta12 (step 53), and when the value of Ta is still small, D
Continue receiving P.

When the last DP is received (step 48), an ACK is sent (step 49), and the series of data transfer processing ends. Note that a is a value much smaller than the value of Tr, and is set so that the value of Ta during time measurement will not jump over the value of Tr. The operation of the transmitting station as described above uses the timer 1-timer group Txll in the internal memory 10 to monitor (Tx) the time from data packet transmission to ACK reception. For example, the timer counter corresponding to DP(1) is assigned to memory address Lot, and the timer counter corresponding to DP(2), which causes 4 o'clock to start from 1 when DP(1) is sent, is assigned to memory address 102, and DP(1) is assigned to memory address Lot. Timing starts with the transmission of (2). Similarly, the counter corresponding to DP(,3) also starts timing when DP(3) is sent out. If ACK #2 is received at this time, the timer counters for DP(1) and DP(2) are cleared and time measurement is stopped, but the timer counter for DP(3) continues to measure time. ACK or NACK
If the timer counter reaches the Tx value before receiving the data packet, transmission is performed again starting from the data packet with the sequence number #n. Further, the Tx is set to a value obtained by adding the time required to transmit the ACK to the value of the Tr.

In this way, by setting a large timeout time Tx on the transmitting station side and not sending ACK until the time just before the receiving station times out, the data can be reduced by the amount of 80K saved. Transfer time is reduced.

Next, as a second embodiment of the present invention, a method using a reception bucket counter will be described with reference to FIGS. 6 to 8.

FIG. 6 is a sequence chart of data transfer showing the second embodiment of the present invention, FIG. 7 is an operation flowchart of the receiving station in FIG. 6, and FIG. 8 shows each area of the internal memory. FIG.

DP(1) to DP(10) in FIG. 6 are data packets with sequence numbers sent out by the transmitting station, and after receiving five data packets, ACK is returned.

At the receiving station, as shown in FIG. 7, the receiving bucket 1 to number counters, X21 and the sequence number of the received DP, #n22 in the internal memory 20 are cleared (step 71), and the DP is received (step 72). If there is an error, N for retransmission request.
ACK is sent (step 74).

The sequence number #n of the correctly received DP is set in the memory, and if it is not the last DP (step 75), X is compared with N, which is the number of packets that determines the I'II interval of ACK transmission ( Step 77), when equal, sends ACK with #n (Step 79), clears received packet number counter, X21 (step 8o)
), continue receiving DP. If the value of

When the last DP is received (step 75), an ACK is sent (step 76), and the series of data transfer processing ends. Note that the operation on the transmitting side for the above is performed using a group of timeout timers in the internal memory 20, Tx23,
The operation may be similar to that of the first embodiment described above. However, Tx at this time is set to a value equal to the transfer time required for the number of data packets for which ACK has been omitted plus a margin.

In this way, the timeout time Tx on the transmitting station side is set to a large value, and the number of ACK occurrences is reduced by the number N of packets specifying the interval between ACK transmissions on the receiving station side, and the data transfer time is reduced as in the first embodiment. is shortened.

Next, as a third embodiment of the present invention, a method using a modulo value for the sequence number of a data packet will be explained.
This will be explained with reference to FIG.

FIG. 9 is a data transfer sequence chart showing a third embodiment of the present invention.

DP(1), DP(2), DP(n)--D in Figure 9
P(X) is a data packet with a sequence number sent by the transmitting station, and is sent repeatedly in the following order: 1st round, 2nd round, 2nd round, 2nd round, etc. Modulo value of 9, the sequence number of ing. Modulo value, X, which is advantageous in software processing
When adopting the sequence number, as the timer value Tr that specifies the return of the ACK increases, the ACK received at the transmitting station will be communicated for the first round, ■, or the second reverse round.
(2) Since it is no longer possible to determine whether the data packet has a sequence number of X, which is also a modulo value, or the last data packet, an ACK is sent to shorten the transfer time. Note that NACK is sent at the time when a data packet check failure occurs.

Next, a method for transmitting ACK only once as a fourth embodiment of the present invention will be explained with reference to FIG. 1θ.

FIG. 1θ is a data transfer sequence chart showing a fourth embodiment of the present invention.

DP in Figure 1O, (1) to DP (5)...
DP(S) is a data packet with a sequence number sent by the transmitting station, and the last data is transferred with the sequence number S. There are limitations depending on the amount of data transferred and the reliability of the communication line, but for all data transfer,
By adopting a method of returning ACK only once at the end, the transfer time is shortened.

In the previous embodiments, since the data packet transmission processing time and the ACK transmission processing time are almost equal,
By reducing the number of ACKs sent, the time required for data transfer can be significantly shortened.

Effects As explained above, according to the present invention, it is possible to reduce the number of ACK returns in a protocol that has a packet communication function, so the time required for data transfer between stations is shortened by the amount of ACKs reduced. be done.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of each station in data communication.
FIG. 2 is a conventional general data transfer sequence chart, and FIGS. 3, 6, 9, and 10 are data transfer sequence charts 1 showing embodiments of the present invention, respectively.
-1 FIG. 4 and FIG. 7 are operation flowcharts of the receiving station in the present invention, and FIG. FIG. 8 is a diagram showing each area of the internal memory. 1.1': Information processing section, 2.2': Communication control section. 3.3', 10.20: Memory, 4: Communication line, 11
~13°21.22: Various areas in memory. Figure 1 Figure 2 Figure 3 Transmitting station A Receiving station B Procedural amendment (voluntary) June 11, 1980 Patent Office Commissioner Kazuo Wakasugi Room 6-1 Indication of the case 1982 Patent Application No. 079617 2 , Title of the invention Communication control system 3, Relationship with the case of the person making the amendment Patent applicant 4, agent 5, Bean Number of inventions increased by amendment None (1) ``Transfer response'' on page 2, line 15 of the specification ``line'' to ``transfer response''
(delete lines). (2) Correct "between stage and partner" in line 18 of page 2 of the specification to "between stations" (delete partner). (3) On page 3 of the specification cylinder, line 10 to line 11, [packet configuration is set to P(1), receiving station B transmits, J is set to ``packet configuration, first packet is set to DP(1), and received. Station B
and correct it to ``. (4) “Received ACK” on page 3, lines 12 to 14 of the specification
#1 is f x ') OK (7) If the above D
P (1) ``Added 1'' is corrected to ``If the check is OK, that is, ACK #l is received, then 1 is added.'' (5) "Increase" on page 3, line 20 of the specification is corrected to "increase". (6) Change r(Tr-a) on page 5, line 11 of the specification to r(Tr
-A)”. (7) Change r(Tr-a) on page 5, line 12 of the specification to r(T
r-A)”. (8) Change “a” on page 5, line 19 of the specification to “A”
”. (9) “Start DPJ” on page 6, line 7 of the specification.
Start it and correct it to DPJ. (10) Correct (replace) Figures 2 and 4 as shown in the attached sheet.

Claims (5)

[Claims] (1) In a communication station equipped with a main CPU and a communication control device, and having a packet communication means, the communication control device receives a plurality of data packets from a partner station, checks the plurality of data packets, and A communication control method characterized in that one response is sent back to the user. (2) The communication control device according to claim 1, wherein the communication control device has a timer that measures time while receiving data packets from the other station, and returns a response when the timer completes timing. control method. (3) Claims characterized in that the communication control device has a counter that counts the number of data packets received from the other station, and returns a response when the cough counter reaches a predetermined number. The communication control method described in paragraph 1. (4) When the communication control device receives a data packet from a partner station to which a sequence number that repeats with a specified modulo value is added, the communication control device transmits a data packet whose sequence number is the specified modulo value. 2. The communication control system according to claim 1, wherein a response is sent back upon reception of the communication control method. (5) The communication control method according to claim 1, wherein the communication control device returns a response when receiving all data packets from the partner station.