JP2564499B2 - Transmission data flow control method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication system, and more particularly to various logical / physical / electrical devices that accommodate a plurality of data line termination positions and are different in correspondence with a data line termination device. TECHNICAL FIELD The present invention relates to a transmission data flow control method in a communication control device having a line connection unit for connecting a physical interface and a line common control unit for commonly controlling a plurality of line connection units.

[Conventional technology]

The basic configuration of the data communication system is shown in FIG. Although not shown in FIG. 5, the communication control devices 1a and 1b are each connected to a central processing unit (CPU), and control the data communication with the partner device independently of the central processing device. The communication control device 1a comprises a plurality of line connection parts 12a having different logical / physical / electrical interfaces corresponding to the data line termination device, and a line control part 11a for commonly controlling these line connection parts 12a. Each line connection unit 12a is connected to the corresponding data line termination device 2a by a cable 4a. The configuration of the communication control device 1b is also the same, and each line connection unit 12b is connected to the corresponding data line termination device 2b by a cable 4b. A high-speed data communication line 3 connects the data line terminators 2a and 2b.

Data communication between the communication control devices 1a and 1b is performed by the line common control unit 11a-line connection unit 12a-cable 4a-data line termination device 2a-data communication line 3-data line termination device 2b-cable 4b-line connection unit. 12b-on the route of the line common control unit 11b.

By the way, in such a data communication system, in recent years, a data line terminating device in which the transfer capability between the data line terminating devices dynamically fluctuates due to the characteristics of the transfer data, the quality of the data communication line, etc. has appeared. . In order to effectively utilize the constant transfer capacity by using such a data line terminating device, the transfer speed between the communication control device and the data line terminating device should be equal to or higher than the average transfer capacity between the data line terminating devices, and It is necessary to absorb the difference in transfer rate by providing a transmission data buffer in the data line terminating device and performing flow control with the communication control device.

Conventionally, the flow control of the transmission data between the data circuit terminating device and the communication control device has been realized by the configuration shown in FIG. In FIG. 3, 1 is a communication control device,
Reference numeral 2 is a data line terminating device, and 3 is a data communication line.
The communication control device 1 is divided into a line common control unit 11 and a line connection unit 12, and the line connection unit 12 has a transmission circuit 120. Although there are a plurality of line connection units 12, only one is shown here. 13 is a transmission character request signal from the transmission circuit 120 to the circuit common control unit 11, 14 is a transmission resumable notification signal from the line connection unit 12 to the line common control unit 11, and 15 is a line common control unit 11 and the transmission circuit 120. It is a transmission data line between. Reference numeral 41 is a signal for restarting transmission from the data line terminal 2 to the line connection unit 12,
Reference numeral 42 is a transmission data line between the transmission circuit 120 and the data line terminating device 2.

The processing flow of FIG. 3 is shown in FIG. The data line termination device 2 turns on the transmission resumable notification signal 41 when data transmission to the data communication line 3 becomes possible, and turns off the transmission resumable notification signal 41 when temporarily suspending data transmission. The line connection unit 12 transmits the transmission resumable notification signal 41 as it is to the line common control unit 11 as the transmission resumable notification signal 14. On the other hand, the transmission circuit 120 of the line connection unit 12 until the data transmission completion instruction is received from the line common control unit 11.
Every time the previous transmission data is transferred to the data line terminating device 2 and becomes empty, the transmission character request signal 13 is turned on in order to obtain the next transmission data to be transferred. This is uniquely issued regardless of whether the transmission resumable notification signal 14 (41) is on or off. When the line common control unit 11 receives ON of the transmission character request signal 13 from the transmission circuit 120, the line common control unit 11 determines the state of the transmission resumability notification signal 14 from the line connection unit 12, and the transmission resumability notification signal 14 is ON. If so, the data is transferred to the transmission circuit 120 via the transmission data line 15, and if the signal 14 is off, the data transfer is suspended. When the transmission circuit 120 receives the data from the line common control unit 11, it transfers it to the data line termination device 2 via the transmission data line 42, and when it becomes empty, turns on the transmission character request signal 13 again. The data line terminating device 2 sends the data received from the transmission circuit 120 to the data communication line 3 in accordance with the quality of the data communication line 3. Then, when the data communication is temporarily stopped, the transmission resumable notification signal 41 is turned off, and when the data transmission to the data communication line 3 becomes possible, the signal 41 is turned on.

[Problems to be Solved by the Invention]

As described above, in the conventional transmission data flow control method, in the communication control device, the resumable transmission notification signal from the data line terminating device to the line connection unit is restarted as it is from the line connection unit to the line common control unit. It is transmitted as a possible notification signal. Therefore, when the line common control unit receives the transmission character request signal ON from the transmission circuit of the line connection unit, the line common control unit determines whether the transmission resumable communication signal from the line connection unit is ON or OFF. If the transmission resumable notification signal is off, the transmission character is not set to the transmission circuit, the data transmission is temporarily stopped, and if the transmission resumable notification signal is on, the transmission character is set to the transmission circuit, A process of restarting data transmission is required for each transmission character request, and a common line that controls a plurality of line connection units that connect different logical / physical / electrical interfaces that differ depending on the data line termination device There is a problem that the load on the control unit increases. Further, there is a problem that the connection between the line connection unit and the line common control unit becomes complicated and the number of connection pins in the line common control unit increases.

It is an object of the present invention to reduce the load on the line common control unit in a communication control device, simplify the connection between a plurality of line connection units and the line common control unit, and connect the line common control unit for transmission resumable notification signal. An object of the present invention is to provide a transmission data flow control method that enables reduction of pins.

[Means for solving the problem]

In order to achieve the above object, in the present invention, in the line connection unit, the transmission resumable notification signal from the data line termination device and the transmission character request signal from the transmission circuit are ANDed,
The output is newly used as a transmission character request signal to the line common control unit.

[Work]

When the transmission resumable notification signal from the data line termination device is off, the transmission character request signal from the line connection unit to the line common control unit is off regardless of whether or not there is a transmission character request in the transmission circuit, and the data line termination device. When the transmission resumable notification signal from is ON, and there is a transmission character request in the transmission circuit, the transmission character request signal from the line connection unit to the line common control unit is turned ON. The line common control unit pays attention only to the transmission character request signal from this line connection unit, and transfers the transmission data to the line connection unit when the transmission character request signal is on.

This eliminates the need for the line common control unit to determine whether or not there is a notification that transmission can be restarted, and the line common control unit only needs to process transmission character requests from the line connection unit to reduce the load on the line common control unit. You can Further, since the transmission resumable notification signal from the line connection unit to the line common control unit can be omitted, simplification of the connection between the line connection unit and the line common control unit and the connection for the transmission resumable notification signal in the line common control unit. The number of pins can be reduced.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of one embodiment of the present invention. In FIG. 1, 1 is a communication control device, 2 is a data line terminating device,
3 is a data communication line. The communication control device 1 is divided into a line common control unit 11 and a line connection unit 12. As shown in FIG. 5, there are actually a plurality of line connecting units 12, but only one is shown here. The transmission circuit 120 is provided in the line connection unit 12.
There is. 13 is a transmission character request signal from the line connection unit 12 to the line common control unit 11, and 15 is the line common control unit 11 and the transmission circuit 120.
Is a transmission data line between. Further, 41 is a notification signal of resumable transmission from the data line terminating device 2 to the line connection unit 12, 42
Is a transmission data line between the transmission circuit 120 and the data line terminating device 2.

Now, in FIG. 1, the line connection unit 12 includes an AND circuit 121 in addition to the transmission circuit 120. The transmission character request signal of the transmission circuit 120 becomes one input of this AND circuit 121,
The other input of the circuit 121 is connected to the data line terminating device 2
From which the resumable transmission notification signal 41 is given. And
The output of the AND circuit 121 becomes the transmission character request signal 13 to the line common control unit 11.

The processing flow in the case of FIG. 1 is shown in FIG. When the transmission resumable notification signal 41 from the data line terminating device 2 is on and there is a transmission character request in the transmission circuit 120, the output of the AND circuit 121 is on, and the line connection unit 12 transfers to the line common control unit 11. The transmission character request signal 13 is turned on. Upon receiving the transmission character request signal 13 from the line connection unit 12, the line common control unit 11 transfers the data (character) to the transmission circuit 120 via the transmission data line 15 and sets the transmission character to the transmission circuit 120. To do. The transmission circuit 120 includes the line common control unit 11
When the data is received from, the data is transferred to the data line terminating device 2 via the transmission data line 42. In the data line terminating device 2, the transmission circuit is adjusted according to the quality of the data communication line 3.
The data received from 120 is transmitted to the data communication line 3. When the transmission circuit 120 transfers the data to the data line terminating device 2, the transmission character request turns on again. At this time, if the transmission resumable notification signal 41 from the data line terminating device 2 is still on, the AND circuit 121 causes the line connection unit
The transmission character request signal 13 from 12 to the line common control unit 11 is turned on again. In this way, the next data is transferred from the line common control unit 11 to the transmission circuit 12 via the transmission data line 15.

On the other hand, when the transmission resumable notification signal 41 from the data line terminating device 2 is off, the output of the AND circuit 121 is off regardless of the transmission character request in the transmission circuit 120, and the line connection unit
The transmission character request signal 13 from 12 to the line common control unit 11 is turned off. In this case, the line common control unit 11 uses the transmission circuit 120.
The transmission character setting for is suspended, so that the data transmission is temporarily stopped. After that, the transmission resumable notification signal 41 from the data line terminal 2 is turned on again, and if the transmission character request in the transmission circuit 120 of the line connection unit 12 is turned on, the data transfer is resumed.

As described above, with the configuration shown in FIG. 1, the line common control unit 11 does not need to perform the process of determining whether or not there is a notification of transmission resumability, and the line common control unit 11 only needs to send character requests from the line connection unit 12. It suffices to focus on the processing. Further, the transmission resumable notification signal from the line connection unit 12 to the line common control unit 11 can be omitted.

〔The invention's effect〕

As described above, according to the present invention, a plurality of line connection units having different logical / physical / electrical interfaces corresponding to the data line termination device and a line common control for common control of the plurality of line connection units are provided. In the communication control device having the control unit, when the flow control of the transmission data is performed, the transmission pause process and the transmission restart process in the line common control unit are not necessary, and the process is reduced as compared with the conventional method. There is an advantage that the load on the control unit can be reduced. Further, according to the present invention, since the transmission resumable notification signal can be omitted from the line connection unit to the line common control unit, simplification of the connection between the plurality of line connection units and the line common control unit and the line common control unit. There is also an advantage that it is possible to reduce the number of connection pins for the notification signal for resuming transmission in the above.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention, FIG. 2 is a processing flow diagram of FIG. 1, and FIG. 3 is a block diagram showing a configuration of a conventional transmission data flow control system, and FIG. FIG. 5 is a processing flow chart of FIG. 3, and FIG. 5 is a block diagram showing a basic configuration of a data communication system targeted by the present invention. 1 ... communication control device, 11 ... line common control part, 12 ... line connection part, 13 ... transmission character request signal, 15 ... transmission data line, 120 ... transmission circuit, 121 ... AND circuit, 2 ...... Data line terminating device, 3 …… Data communication line, 41 …… Transmission resumable notification signal, 42 …… Sending data line.

Claims (1)

(57) [Claims] 1. A flow control of transmission data in a communication control device having a plurality of line connection units for connecting various different interfaces corresponding to a data line termination device and a line common control unit for commonly controlling the plurality of line connection units. The method, wherein the line connection unit receives a transmission resumable notification signal that is turned on when data transmission from the data line terminating device to the data communication line is possible, and is turned off when the data transmission is temporarily stopped, When the transmission resumable notification signal is ON, a transmission character request signal is sent to the line common control unit each time a transmission character request is generated in the line connection unit, and when the transmission resumable notification signal is OFF, the line connection unit Even if a transmission character request occurs, the transmission of a transmission character request signal to the line common control unit is suppressed, and the line common communication control unit transmits from the line connection unit. Each time the character request signal arrives, and transfers the data to the line connection unit, the flow control method for transmitting data, characterized in that.