JPH05300190A - Data communication method - Google Patents

Abstract

PURPOSE:To perform the data communication with good transmission efficiency regarding a data communication system for which plural terminal equipments are connected through a public line network and is link controlled by the high level data link control process (HDLC) of a normal response mode(NRM). CONSTITUTION:In the data communication method of the data communication system in which plural terminal equipments 1 and 3 are connected through a public line network 2, the terminal equipments 1 and 3 are provided with a transmission data preparing means 11 to prepare the transmission data of which the number of frames is one frame less than the maximum number of the frames available at one transmittable time. The terminal equipment 1 on the transmitting side transmits the transmission data composed of the frame including information that is not the final frame of the number of the frames having one frame less than the maximum transmission frames to the terminal equipment 3 on the receiving side ant it transmits the next transmission data when there is a response from the terminal equipment 3 on the receiving side, and it transmits the frame as the final frame provided with the information to indicate that it is the final frame when there is not the response from the terminal equipment 3 on the receiving side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a data communication system connected via a public line network such as DN, and particularly to a high level data link control procedure (H
The present invention relates to a data communication method of a data communication system in which link control is performed by a normal response mode (NRM) in DLC.

High level data link control procedure (hereinafter,
A system that performs data communication by HDLC) includes a primary station (hereinafter referred to as P station) that performs data link control and a secondary station (hereinafter referred to as S station) that performs data communication according to an instruction from the P station. Determined.

[0003]

2. Description of the Related Art Conventionally, when transmitting data from an S station to a P station, the P station sends a P bit on command to the S station to permit data transmission, and the S station sends a P bit on command. By receiving, the data of the maximum number of frames that can be transmitted is transmitted as one transmission unit. And, in the last frame of one transmission unit,
Turn on the F bit indicating the last frame, and set P
When the station receives the F-bit-on frame, it sends the P-bit-on transmission permission command to the S station.

FIG. 5 shows a conventional data transfer system. In the figure, 100 is a transmission permission command of the P station,
The permission of transmission is given from the P station to the S station. AA represents a command, P represents one bit of ON or OFF, and P bit ON represents transmission permission (P bar represents P bit OFF). Reference numeral 101 denotes transmission data, which represents one transmission unit transmitted from the S station to the P station. I represents the information of the transmission data, and F represents the final frame. F is one bit that is on or off, and F bit on represents the final frame. The transmission data is composed of the maximum number of transmission frames (N). Reference numeral 103 is the final frame of transmission data, and the F bit is turned on. Reference numeral 104 represents a transmission permission command following the transmission data 101, and 105 represents the next transmission data transmitted according to the transmission permission command 104.

In the conventional transmission method, when the S station receives the transmission permission command 100 from the P station, the S station transmits the transmission data 1
01 is transmitted frame by frame to the P station. Every time the P station receives several frames, it returns to the S station a reception command such as a normal reception of P-bit off or a retransmission request when it cannot be received. Then, when the P station detects the final frame with the F bit on, it sends a command for permitting the transmission of the P bit on to the S station. Upon receiving the transmission permission command from the P station, the S station transmits the next transmission data.

[0006]

In the conventional transmission from the S station to the P station, the transmission data of the maximum number of transmission frames was transmitted to the P station with the F bit of the last frame turned on. Could not send the next transmission data only after receiving the transmission permission command from the P station. Therefore, the conventional data communication method has poor transmission efficiency.

An object of the present invention is to provide a data communication method with good transmission efficiency.

[0008]

According to the present invention, the maximum transmission frame that can be transmitted at one time is considered in view of the fact that the reception of data to the P station is secured as long as the transmission data of F bit off is transmitted. When the number is N, the number of frames of transmission data to be transmitted at one time is N-1, and the N-1th frame is transmitted with the F bit off. Then, upon reception of a P-bit off reception command for the N-1th frame, the transmission data of the next N-1 frame is transmitted.

FIG. 1 is a diagram showing the basic configuration of the present invention. In the figure, 1 is a terminal device (S station) of a secondary station. 2 is a public line network, such as ISDN. 3 is a terminal device (P station) of the primary station.

Reference numeral 10 is a data holding means for holding data to be transmitted. Reference numeral 11 is a transmission data creating means for creating N-1 frames of transmission data frame by frame. An F bit setting means 13 sets ON or OFF F bit for each frame of transmission data.

Reference numeral 14 denotes a control unit which controls transmission data creation and transmission data transmission in accordance with a reception command from the P station 3. 15 is a transmitting / receiving unit,
Reference numeral 16 is a receiving unit that receives a reception command or the like sent from the P station 3 via the public line network 2.
Reference numeral 17 denotes a transmission unit that transmits the transmission data created by itself to the P station 3 via the public line network 2.

[0012]

The operation of the configuration of FIG. 1 will be described with reference to FIG. When the reception unit 16 receives the P-bit-on transmission permission command 21 sent from the P station 3, the reception unit 16 notifies the control unit 14.

When the control unit 14 receives the transmission permission command 21, it transmits the transmission data 2 by the transmission data creating means 11.
2 control is performed. The transmission data creating means 11 creates a frame number, transmission information, and an F-bit-off frame for each frame, and one transmission data creates up to N-1 frames with respect to the maximum transmission frame number N (FIG. 2). (A)
reference).

The created transmission data 22 is sent to the transmission unit 17 every time one frame is created. When sending the transmission data from the S station 1 to the P station, the P bit off reception command is sent every time one frame is sent from the P station 3.
The transmitter 17 transmits the next frame each time. While the transmission unit 17 is transmitting the transmission data 22, the transmission data creating means 11 sends the next transmission data 23 to the transmission unit 17 every time one frame is created.

When the S station 1 receives the reception command for the (N-1) th frame, the control section 14 instructs the transmission of the next transmission data (N-1 frame) 23. Then, the transmitter 17 transmits the next transmission data frame by frame,
Send to station P. When there is no receive command from the P station for the N-1th frame (see FIG. 2B), the transmission data creating means 11 turns on the F bit for the next Nth frame. Transmission data 22 '(representing the last frame) is created. Transmitter 1
7 transfers the Nth frame 23 '. Then,
When the P-bit-on transmission permission command 24 is received from the P station, the S station receives the next transmission data (N-1 frame) 23.
Are transferred to the P station by the same procedure.

The last frame of the transmission data of the last transmission of the data to be transmitted has the F bit on. According to the present invention, since it is not necessary to receive the transmission permission command of the P station each time the transmission data is transferred, there is no idle time in the transmission path. Therefore, the data transfer processing efficiency is improved.

[0017]

FIG. 3 is a diagram showing the construction of an embodiment of the present invention. The figure shows the case where the present invention is applied to ISDN.

In the figure, 31 is a terminal device (S station). Reference numeral 32 denotes a data storage means, which is composed of a disk device or the like. 33 is a main memory, 34 is a CPU, 35
Is a bus and 36 is a transmission / reception unit.

In the transmitting / receiving unit 36, 37 is an INAC
(ISDN ADAPTER CONTROLLER)
In addition, MPC (described later) 40 and 41 is coupled to the bus. The INAC 37 controls the priority of the two MPCs. 38 is S-busRO
M stores the identification number of the device.
Reference numeral 39 is a LocalRAM, which holds transmission / reception data in the DMA control of the MPCs 40 and 41. MPC1 and MPC2 (multi-protocol controller) 40 and 41 respectively perform data transfer control by DMA, convert parallel data to be transmitted into serial data, and convert received serial data into parallel data. Reference numeral 42 denotes an RIU, which, when processing at 64 Kbps, for example, when the partner terminal device processes at a lower speed of 9600 bps, matches the speed. Reference numeral 43 is an SIFC, which controls the protocol layer 1. Reference numeral 44 denotes a transformer that blocks a direct current component. Reference numeral 45 is a DSU, which is a line terminating device.

Reference numeral 50 is a buffer, which holds data. Reference numeral 51 is a transmission data creation unit. In the transmission data creating means 51, reference numeral 52 is a frame number detection unit in the buffer, which detects the number of data items to be frame created in the buffer 50. Reference numeral 53 is a frame data creation unit that creates a frame. 5
Reference numeral 4 denotes a response detection unit that determines whether or not the transmission / reception unit 36 has received a reception command from the P station.
A timer setting unit 56 sets a timer. 57 is a timer.

FIG. 4 shows a flow of the transmission data creating means and the transmitting / receiving section of the present invention. The flow will be described according to the numbers shown (see FIG. 4). (1), (1) 'Data is input to the buffer 50. The frame number detection unit 52 in the buffer 50 determines whether or not the data to be transmitted to the buffer 50 is equal to or more than the maximum transmission frame number N. If it remains, proceed to (2). If not, proceed to (8).

(2) The frame data creating section 53 creates a frame of maximum transmission frame number-1 and transfers it to the transmitting / receiving section 36. The transmission / reception unit 36 performs a transmission process. (3) The response detection unit 54 determines whether or not there is a received command response from the P station. If there is a response, proceed to (4), and if there is no response, proceed to (5).

(4) The frame data creating section 53 creates a frame of maximum transmission number -1 including unconfirmed frames that have not been received, and transfers it to the transmitting / receiving section 36. The transmission / reception unit 36 performs a transmission process. (1) Repeat the following processing.

(5) When there is no response of the received command from the P station in the judgment of (3), the timer setting section 56 sets the timer. (6), (7) The F bit setting unit 55 turns on the F bit of the Nth frame and transmits when the time-out occurs.

(8) If the number of data in the buffer 50 is equal to or less than the number of transmission frames (N-1), the frame data creating section 53 turns on the F bit of the final frame and transmits. INDUSTRIAL APPLICABILITY The present invention is particularly effective in a communication processing method in which, when the created frame is transferred to the transmission / reception unit in the S station, it is transferred without waiting for the transmission completion notification of layer 1 (transmission completion notification from layer 1 If the created frame is sent to the transmission / reception unit after waiting, the transmission permission command from the P station has already been notified at the time when the transmission completion notification is sent. Therefore, even if the method of the present invention is not used. Good).

Further, the present invention is particularly effective when the S station and the P station are connected in a one-to-one relationship, since the P station is exclusively occupied by the S station.

[0027]

According to the present invention, the S station can transmit up to the last frame of all the transmission data while maintaining the transmission priority right secured once without waiting for the transmission permission command from the P station again. Therefore, the communication time until all the transmission data is transmitted is shortened. Therefore, the transmission efficiency of the transmission line can be significantly improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of the present invention.

FIG. 2 is an operation explanatory diagram of the present invention.

FIG. 3 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 4 is a diagram showing a flow of a transmission data creating means and a transmission / reception unit of the present invention.

FIG. 5 is a diagram showing a conventional data transfer method.

[Explanation of symbols]

 1: Terminal device (S station) 2: Public line network 3: Terminal device (P station) 10: Data holding means 11: Transmission data creating means 12: Transmission data 13: F bit setting means 14: Control section 15: Transmission / reception section 16: Receiver 17: Transmitter

Claims (3)

[Claims] 1. A plurality of terminal devices (1, 3) are connected to a public line network.
In the data communication method of the data communication system connected via (2), the receiving side terminal device (3) and another terminal device (1) are defined as the transmitting side terminal device, and the transmitting side terminal device (1) From 1
The transmission data of one time is composed of a plurality of frames, each frame is added with information indicating that it is the final frame or not, and the receiving side terminal device.
In (3), when the last frame is received, a transmission permission command is sent, and when a frame that is not the last frame is received, a command different from the transmission permission command is sent as a response. Based on the command indicating the transmission permission from the terminal device (3), the sending terminal device (1) starts transmission to the receiving terminal device (3), and the receiving terminal device (3) Unless the frame including the information indicating that the frame is transmitted, the transmission data can be continuously transmitted without receiving the transmission permission reception command, and the terminal device (3) can transmit the data once. The terminal device (1) on the transmitting side is provided with the transmission data creating means (11) for creating the transmission data of one frame less than the maximum number of frames, and the terminal device (1) on the transmission side is the final frame of one less than the maximum number of transmission frames. If the terminal device (3) on the receiving side receives a response, it sends the next transmission data, and the terminal device on the receiving side ( 3) A data communication method characterized in that if there is no response, the information indicating the final frame is given and the frame is transmitted as the final frame. 2. The data communication system according to claim 1, wherein the primary station (3) performs data link control, and the primary station (3).
And a secondary station (1) that performs data communication in response to the instruction of
A data communication method characterized by a high-level data link control procedure in a normal control response mode. 3. The terminal device according to claim 1, wherein the terminal device transmits the transmission data from the upper layer to the layer 1 without waiting for a transmission completion notification after one frame from the layer 1 of the communication protocol. Data communication method.