JPH04286440A - Communication controller - Google Patents

Abstract

PURPOSE:To automatically change the communication speed into an optimum communication speed in response to a data error rate even in the communication state. CONSTITUTION:Upon the detection of an error in a frame data received through a line connection line 12, an error detection circuit 17 reports it to a reception frame error detection frequency measurement section 14 and makes a request of transmission of an error check notice frame leading to an opposite station to a central controller (not shown). On the other hand, when an error detection notice frame as to the frame data sent to the opposite station is sent from the opposite station, the frame is transferred to a transmission frame error detection frequency measurement section 15. The count of a counter 19 is counted up by every error detection report from the reception frame error detection frequency measurement section 14 and the transmission frame error detection frequency measurement section 15 and the result is reported to a speed command circuit 18 for each prescribed time. The speed command circuit l8, based on the report, instructs re-setting of a proper data transmission speed to a communication controller main body 11.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication device, and more particularly to a communication control device having a function of detecting errors in data transmitted in frame format.

0002

[Background Art] Normally, data communication carried out in so-called frame units via a communication line follows a predetermined transmission control procedure, but in order to ensure its reliability, data error detection is generally performed. There are many things. By notifying the other party of this data error detection, retransmission is encouraged, and based on the frequency of error detection, it is determined whether the data transmission rate being used is appropriate. For example, if the line conditions are poor and the frequency of data error detection is high, the data transmission speed may be reduced to suppress data errors.
When the data error detection frequency is extremely low, changes such as increasing the data transmission speed are made.

In conventional communication control devices, when changing the speed, the line is temporarily disconnected to terminate the communication, and after changing the data transmission speed, the communication is started again.

0004

[Problems to be Solved by the Invention] As described above, in conventional communication control devices, in order to change the data transmission speed, communication is once terminated and the connection is released, and then communication is restarted. It was not possible to make that change inside. Therefore, even if the error frequency fluctuates significantly due to deterioration of the line condition, it is not easy to change the transmission speed to the optimum transmission rate. Therefore, in the worst case, resetting is required due to disconnection of data links due to increased retransmission processing, resulting in a drawback that communication efficiency is significantly reduced.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a communication control device that can automatically change the transmission rate to the optimum transmission rate depending on the data error rate even during communication.

[0006]

[Means for Solving the Problems] The invention as set forth in claim 1 includes (i) error detection means for detecting errors in data transmitted in frame format via a communication line; (ii)
(iii) error detection frequency measuring means for measuring the frequency with which the error detection circuit detects errors in received frame data;
The communication control device is provided with data transmission rate instructing means for instructing resetting of the data transmission rate in accordance with the error detection frequency measured by the error detection frequency measuring means.

In the first aspect of the invention, the data transmission rate is reset in accordance with the measured value of the frequency of error detection in received frame data.

[0008] In the invention as claimed in claim 2, (i) error detection means for detecting errors in data transmitted in frame format via a communication line; and (ii) this error detection circuit detects errors in received frame data. (iii) a transmission unit that measures the frequency of reception of error detection notification frames sent from a partner station to notify the detection of errors in transmitted frame data; The communication control device is equipped with a frame error detection frequency measuring means, and (iv) a data transmission rate instruction means for instructing resetting of the data transmission rate according to the error detection frequency measurement values by these two error detection frequency measuring means. let

In the invention as claimed in claim 2, the data to be reset is determined in consideration of both the measured value of the frequency of error detection of received frame data and the measured value of the frequency of error detection of transmitted frame data. Let us decide the transmission speed.

0010

EXAMPLES The present invention will be explained in detail with reference to Examples below.

FIG. 1 shows a communication control device in one embodiment of the present invention. A main body 11 of this device is connected to a communication network (not shown) via a line connection line 12. Connected to this main body 11 are a reception frame error detection frequency measurement section 14 , a transmission frame error detection frequency measurement section 15 , and an error frequency measurement section 16 having a counter 19 .

Of these, the received frame error detection frequency measuring section 14 is connected to an error detection circuit 17 in the main body 11, and the transmitted frame error detection frequency measuring section 15 is connected to a receiving section (not shown) in the main body. These two measuring sections are also connected to a counter 19. The counter 19 is connected to a speed instruction circuit 18, and this speed instruction circuit 18 is further connected to a central control device (not shown) in the communication control device main body 11.

The operation of the communication control device configured as above will be explained. Communication line network and line connection line 12 from the other station
The frame data sent via the communication control device main body 11 is sent to the error detection circuit 17 via a receiving section (not shown) in the communication control device main body 11.
is input. The error detection circuit 17 extracts an error check code from the received frame data, and performs predetermined processing to check whether or not there is an error in the data. As a result, if there is an error, the error is reported to the central control unit and also to the received frame error detection frequency measuring section 14 of the error frequency measuring section 16. The received frame error detection frequency measuring unit 14 that receives this starts the counter 19.
Add 1 to the value of . The central control unit that receives this report creates an error detection notification frame in a predetermined format, and controls a transmitter (not shown) to transmit it to the partner station.

On the other hand, normal frame data transmitted from a transmitter (not shown) in the communication control device main body 11 is received by the other station via the line connection line 12 and the communication network. If the other station detects an error in this data,
An error detection notification frame in the same format as described above is transmitted. This error detection notification frame is received by the receiving section of the communication control device main body 11 via the line communication network and the line connection line 12, and is further transferred to the transmission frame error detection frequency measuring section 15 of the error frequency measuring section 16. In the transmission frame error detection frequency measurement unit 15 that receives this, the counter 19
Add 1 to the value of .

In this manner, the counter 19 is incremented each time an error is detected in the frame data transmitted to the partner station and the frame data received from the partner station. A control section (not shown) in the error frequency measurement section 16 checks the value of the counter 19 at fixed time intervals predetermined for each data transmission speed, and sends error frequency data corresponding to the value to the speed instruction circuit 18. Send. The reason why we decided to set a fixed time for each data transmission speed here is because, for example, if we set a fixed time regardless of the data transmission speed, the higher the speed, the more data arrives per unit time. This is because it is recognized that the frequency of error occurrence is low. Therefore, for example, the count value may be checked at intervals whose length is inversely proportional to the data transfer rate.

The speed instruction circuit 18 that receives the error frequency data from the error frequency measurement section 16 determines how much the data transmission speed should be reduced based on the value of the data, and sends the information to the central control device of the communication control device main body 11. Instruct to that effect. The determination in this case can be easily made by, for example, storing the speed data to be reset in association with each error frequency data in a table format and referring to this table.

The central control unit of the communication control device body 11 that receives the instruction from the speed instruction circuit 18 resets the data transmission rate to the instructed value, and thereafter receives a speed reset instruction from the speed instruction circuit 18. Data transmission is possible at this speed.

Thereafter, when the data error detection frequency decreases due to recovery of the line condition, for example, the error frequency measuring section 1
6, error frequency data of a corresponding value is transferred to the speed instruction circuit 18. Upon receiving this, the speed instruction circuit 18 gives an instruction to the central control speed of the communication control device main body 11 to return the data transmission speed to its original value. This restores the data transmission rate to its original value.

In this embodiment, the count 19 counts the occurrence of errors in both received frame data and transmitted frame data, but for example, the count 19 counts the occurrence of errors in both received frame data and transmitted frame data. It is also possible to separately provide a counter for each of the 15 and separately count the error frequency of received frame data and the error frequency of transmitted frame data. In this case, error frequency can be detected for each transmission direction, and speed control can be performed more precisely.

Of course, error detection may be performed only on either the received frame data or the transmitted frame data, and the data transmission rate may be determined based on the frequency of error detection.

[0021]

As explained above, according to the invention set forth in claim 1, the data transmission rate is sequentially reset according to the measured value of the frequency of error detection in received frame data, so that the line This enables communication at data transmission speeds that match the situation. This makes it possible to avoid the occurrence of data errors and the resulting increase in retransmission processing, and has the effect of minimizing the occurrence of data link disconnections, line reconfigurations, etc. caused by these errors.

[0022] According to the second aspect of the invention, the resetting is performed in consideration of both the measured value of the frequency of error detection of received frame data and the measured value of the frequency of error detection of transmitted frame data. Since the desired data transmission rate is determined, there is an effect that the data transmission rate can be controlled more precisely.

[Brief explanation of the drawing]

FIG. 1 shows a communication control device in an embodiment of the present invention.

[Explanation of symbols]

11 Communication control device body 12 Line connection line 14 Received frame error detection frequency measurement section 15 Transmission frame error detection frequency measurement section 16 Error frequency measurement section 17 Error detection circuit 18 Speed instruction circuit 19 Counter

Claims (2)

[Claims] 1. Error detection means for detecting errors in data transmitted in frame format via a communication line; Error detection frequency measurement means for measuring the frequency with which this error detection circuit detects errors in received frame data. , and data transmission rate instructing means for instructing resetting of the data transmission rate in accordance with the measured value of the error detection frequency by the error detection frequency measuring means. 2. Error detection means for detecting errors in data transmitted in frame format via a communication line, and received frame error detection frequency measurement for measuring the frequency with which this error detection circuit detects errors in received frame data. a transmission frame error detection frequency measuring means for measuring the reception frequency of error detection notification frames sent from a partner station to notify error detection of transmitted frame data; and these two error detection frequency measuring means. 1. A communication control device comprising: data transmission rate instructing means for instructing resetting of the data transmission rate in accordance with a measured value of error detection frequency.