JP2796617B2 - Communication branching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a high-level data link control procedure (HDLC: Highlevel Data Link Control Procedur
es).

[0002]

2. Description of the Related Art The HDLC system is a high-efficiency synchronous data transmission, and international standardization is carried out without restrictions on codes. In addition, transmission and error checking are performed in units of frames using variable-length frames, and transmission and reception are performed in full-duplex communication while inquiring and confirming the receivable state of the other receiving station in units of frames. As a result, the functions of the transmission control device in the form of an LSI have these functions, so that the load on the computer can be reduced, the transmission efficiency can be improved, and the transmission time can be reduced.

As an example of a transmission control device of a conventional remote monitoring control device using the HDLC system, Japanese Patent Laid-Open No. 2-67853 has a configuration as shown in a block diagram of FIG.
There is an apparatus disclosed in Japanese Unexamined Patent Publication (Kokai) Publication.

In FIG. 1, reference numeral 1 denotes an upper level control station, 2 denotes a lower level control station or a relay station, and 3 denotes a controlled station.

[0005] Each control station (or relay station) 1, 2,
3 includes master transmission procedure control units 4, 56 and modulators 7, 8,
9, demodulators 10, 11, 12 are provided. Also, the lower level control station 2 has a line switch 13 for switching the line between the upper level control station 1 and the lower level control station 2, and the data from the controlled station 3 is transmitted to the lower level control station 1 and the lower level control station 1. A hybrid coupler 14 that branches to both the level control station 2 and a slave transmission unit 16 dedicated to reception are provided. This reception-only slave transmission unit 16 is also provided as reference numeral 15 in the upper level control station 1. The controlled station 3 is provided with a slave transmission unit 17 dedicated to transmission.

Reference numerals 18, 19, and 20 in the control stations (or relay stations) 1, 2, and 3 denote transmission section changeover switches, respectively.
(Or 5, 6) or used by the slave transmission unit 15 (or 16, 17).

The operation of such a conventional transmission control device of a remote monitoring control device will be described below.

The upstream data from the controlled station 3 is input by the modulator 9 to the hybrid combiner 14 of the lower level control station 2. The data branched by the hybrid coupler 14 is transmitted to the demodulators 10 of the upper level control station 1 and the lower level control station 2,
In the upper level control station 1 or the lower level control station 2 which demodulates and controls the downlink data respectively, it is inputted to the master transmission procedure control section 4 or 5 in the other control stations and to the slave transmission section 15 or 16 in other control stations. You.

In the upper level control station 1 or the lower level control station 2 which controls the downlink data, the downlink data of the master transmission procedure control unit 4 or 5 is switched by a line switch.
Since the connection state is established at 13, it is input to the master transmission procedure control unit 6 of the controlled place 3. Therefore, communication by the HDLC method can be performed between the control station 1 (or 2) that controls the downlink data and the controlled station 3.

Control station 2 not controlling downlink data
(Or 1), the other control station 1 (or 2) and the controlled station 3
It is only possible to monitor the upstream data in the communication between and.

[0011]

In the transmission control device of the remote monitoring control device disclosed in Japanese Patent Laid-Open No. 2-67853, the control station does not control the downlink data. Can only monitor the upstream data, so it is not possible to request HDLC data retransmission when a transmission error occurs between the branching device and the control station, resulting in data loss. There is a serious flaw.

Hereinafter, a specific description will be given with reference to the timing chart of FIG.

In the timing chart of FIG. 2, reference symbols I (n) indicate information frames, respectively,
Is a transmission order number by the modulators 7, 8, and 9 in the HDLC system.

RR (m) indicates a frame for confirming reception,
m is a reception order number, and thus indicates that the frames up to the (m-1) th frame have been correctly received.

The frame I (1) transmitted from the controlled station 3 is branched by the hybrid coupler 14 and transmitted to the lower level control station 2 and the upper level control station 1. Next, the controlled site 3
When transmitting the frame I (2), the data was correctly received by the upper-level control station 1 but a transmission error occurred in the data transmitted to the lower-level control station 2 and the data was lost (see FIG. 2). X). In such a case, if the lower level control station 2 uses the slave transmission unit 16 having only the reception function, the HDLC
Cannot send a data retransmission request by the
I (2) will be missing. Note that the subsequent transmission of the frame I (3) is performed normally .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has a high reliability HDLC remote monitoring and control method which does not cause data loss even when monitoring upstream data. An object of the present invention is to provide a communication branching device in a device.

[0017]

Communication branch device according to the present invention SUMMARY OF], due the high level data link control procedure, the controlled
And a lower-level control station that monitors the controlled station ;
With the higher-level control station that monitors and controls the
Communication branching device for remote monitoring and control equipment for data transmission between
In the receive data from the controlled plant, and the data branching unit for both transmitting data to the said on <br/> position level control plants and the lower level control stations, or the data branching unit
Data transmission to the lower-level control station and the
Control transmission between them to respond to the acknowledgment
A first high-level data link control unit and the data branch
From the department to the higher-level control station and
Transmission control between this and the
A second high-level data link control unit to perform, the lower Les
Correctly sent to both the bell control station and the upper level control station.
When the communication data is transmitted, the fact is notified to the controlled station.
And a response control unit for generating a response frame to be notified.
And features .

[0018]

According to the communication branching device of the present invention, when transmitting uplink data from a controlled station to both control stations, if a transmission error occurs in one of the control stations, the data is retransmitted from the control station. It becomes possible to transmit a response frame corresponding to data whose delivery confirmation has been completed at both control stations to the controlled station.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments.

FIG. 3 is a block diagram showing the configuration of the communication branching device according to the present invention and the control stations connected thereto.

In FIG. 3, reference numeral 1 denotes an upper-level control station, 2 denotes a lower-level control station, and 3 denotes a controlled station, which are the same as in the above-mentioned conventional example.

Reference numeral 21 indicates a communication branching device according to the present invention. The communication branching device 21 of the present invention is used for monitoring and controlling data between the controlled plant 3 and the higher-level control plant 1.
While performing the transmission and reception of data the control station to the lower level control stations 2 3
Send data for monitoring . This communication branching device 21
25 and 26 are both high-level data link control (H
HDLC control unit (CC
U). The HDLC control unit 25 is a lower-level control station 2
For this purpose, the HDLC control unit 26 is prepared for each of the upper level control stations 1.

Reference numeral 27 denotes a data branching unit, which transmits data received from the controlled station 3 to the HDLC control units 25 and 26. Reference numeral 28 is a response control unit, and the HDLC control unit 25,
A response frame to the controlled station 3 is generated according to the state of 26. 32, 33, and 34 are all modems (MODEMs).

Reference numeral 2 in the upper level control station 1
4, reference numeral 23 in the lower level control station 2 and the controlled station 3
Reference numeral 22 in the figure is an HDLC control unit for performing data transmission according to the HDLC method.

The operation of the communication branching device of the present invention having such a configuration is as follows.

The data transmitted from the HDLC control unit 22 of the controlled place 3 is transmitted from the modem 29 of the controlled place 3 and input to the data branching unit 27 via the modem 34 of the communication branching device 21. The process branches to both the HDLC controller 25 for the lower level control station 2 and the HDLC controller 26 for the upper level control station 1.

The HDLC control units 25 and 26 are respectively composed of the HDLC control unit 23 of the lower level control station 2 and the HDLC control unit of the upper level control station 1.
Data is transmitted to and from the control unit 24 according to the HDLC method. The HDLC controllers 25 and 26 transmit the data transmission confirmation status to the lower level control station 2 and the upper level control station 1 to the response controller 28, and the response controller 28 completes the transmission confirmation at both control stations 1 and 2. A response frame for generated data is generated and the controlled station 3
Is transmitted to the HDLC control unit 22.

The operation of the data transmission sequence of the communication branching device of the present invention will be specifically described with reference to the timing chart of FIG.

In FIG. 4, reference symbols I (n) denote information frames, respectively, and n is a transmission order number by the modulators / demodulators 29 to 34 in the HDLC system.

RR (m) indicates a reception confirmation frame,
m is a reception order number, and thus indicates that the frames up to the (m-1) th frame have been correctly received. Furthermore, REJ (m)
Is a reject frame for notifying that an information frame having an incorrect transmission sequence number has been received, and m-1
The frames up to the number indicate that the reception has been correctly completed. Incidentally, RR and REJ is a frame for control procedures defined in high-level data link control procedure, the controlled plant from the transfer and higher control plant information to the control plants
Is transmitted by the information frame I described above.

In FIG. 4, the frames I (1), I (2), and I (3) transmitted from the controlled station 3 are branched by the communication branching device 21 of the present invention, and are divided into the lower level control station 2 and the upper level control station 2. Sent to level control station 1. The communication branching device 21 transmits the acknowledgment frame RR (4) to the controlled station 3 when receiving the acknowledgment frame RR (4) from the lower level control station 2 and the upper level control station 1, respectively.

Next, the frame transmitted from the controlled station 3
Although I (4) is branched by the communication branching device 21 and transmitted to the lower-level control station 2 and the upper-level control station 1, as indicated by the crosses in FIG. The operation when the transmission error occurs in 4) will be described.

When the controlled station 3 transmits the next information frame I (5), the higher-level control station 1 follows I (4) following I (4).
Since (5) is also correctly received, it becomes possible to transmit the acknowledgment frame RR (6) to the communication branching device 21. On the other hand, since the lower level control station 2 has received I (5) next to I (3), it transmits a reject frame REJ (4) to the communication branching device 21. This reject frame REJ
In response to (4), the communication branching device 21 generates frames I (4) and I (5).
To the lower level control station 2. When receiving the frames I (4) and I (5), the lower-level control station 2 transmits a reception confirmation frame RR (6) to the communication branching device 21. At the point of receiving, the reception confirmation frame RR (6) is transmitted to the controlled station 3.
Note that subsequent transmission of frame I (6) is not performed normally.
You.

[0034]

As described above in detail, according to the communication branching device of the present invention, the first and second high-level data links are respectively provided for the lower-level control station and the upper-level control station.
Has a click control unit, the further transmission for the acknowledgment of the controlled plant-friendly was performed after the acknowledgment to both the control plants is completed, the lower performing monitor data from the controlled plant <br/> First and second high-level data link systems at control center
Highly reliable data reception by control procedures becomes possible.

Further, in the communication branching device of the present invention, it is not necessary to prepare a special reception-only slave transmission unit which only monitors the upstream data as in the conventional case, and the standard HDLC control for controlling the HDLC system is unnecessary. It is possible to realize the same function as in the past only by the unit .

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a device disclosed in Japanese Patent Application Laid-Open No. 2-67853 as a conventional example of a communication branching device in a remote monitoring control device based on the HDLC method.

FIG. 2 is a timing chart for explaining the operation of the device of FIG. 1;

FIG. 3 is a block diagram illustrating a configuration of a communication branching device according to the present invention.

FIG. 4 is a timing chart for explaining the operation of the communication branching device of the present invention.

[Explanation of symbols]

 I Data frame RR Reception acknowledgment frame REJ Reject frame 1 Upper level control station 2 Lower level control station 3 Controlled station 21 Communication branching unit 25 HDLC control unit 26 HDLC control unit 27 Data branching unit 28 Response control unit

Claims (1)

(57) [Claims] By 1. A high level data link control procedure between the controlled plant, and the lower level control stations for performing monitoring of the controlled plant, the an upper level control stations for monitoring and control of the controlled plant A data branching unit for receiving data from the controlled place and transmitting data to both the upper-level control station and the lower-level control station. And data transmission from the data branch section to the lower level control station .
Between this order to the delivery and response acknowledgment to this
Data and the first high-level data link control unit that performs transmission control of, from the data branching unit to the upper level control plants
In order to respond to transmission and acknowledgment of transmission ,
And a second high-level data link control unit for performing transmission control between the low-level control station and the high-level control station. A communication branch device comprising: a response control unit that generates a frame.