JP2901020B2 - Data communication method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plurality of transmission lines (LAs).
The present invention relates to a data communication system in a network having N), and more particularly to a data communication system in which a series of data is exclusively communicated between two stations while being divided into a plurality of frames.

[0002]

2. Description of the Related Art LAN (Local Area Network:
In a network such as a Local Area Network, a plurality of devices (hereinafter, referred to as stations) such as workstations and personal computers are arranged on a single transmission line (comprising a twisted pair line, a coaxial cable, an optical fiber, and the like). Connected. In a large-scale LAN having a large number of stations, a plurality of transmission paths are connected to each other via a repeater or the like to form a LAN.

In the above-described computer network, when data communication is performed between stations (stations) connected to the same or different transmission paths, the number of data in a transmission frame is restricted, and the number of data in a transmission destination station is limited. Due to restrictions such as the size of the receiving buffer, one data may need to be divided into a plurality of frames and communicated a plurality of times. At this time, if the data is shared data between stations, communication from another station must be excluded during a series of communication of the data.

In such a case, conventionally, the receiving station determines whether or not it is a part of a series of communication data,
If it is a part of a series of communication data, the transmission source station of the data is identified by the transmission line type of the communication data (information indicating the transmission line to which the transmission source station is connected),
Recognize based on the station number (identification number assigned to the transmission source station), etc., and thereafter process only transmission data from the transmission source station having the same transmission path type and station number. Even if data transmitted from the station is received, the data is not received.

[0005] An example of such data communication is shown in FIG.
This will be described with reference to FIG. First, as shown in FIG. 5A, four stations A, B,
When data is transmitted from station A, B, or D to station C in the network to which C and D are connected, station C receives data from any of stations A, B, or D. In order to be able to recognize whether a station is a station, it is only necessary to have the station number of the transmission source.

There are two transmission lines 31 and 32 as shown in FIG. 5 (B). Station C is connected to the two transmission lines 31 and 32, and stations A and B are connected to transmission line 3
In a network in which the station D is connected to the transmission line 32, the station D and the stations A and B have different transmission lines. Therefore, the same station number as the station A or B is assigned to the station D. May have been. Therefore, the transmission path 31 or 3 to which the source station is connected
2 is required. For this reason, when transmitting a series of data from station A to station C multiple times, if station C wants to exclude communication from other stations other than station A, the station number of station A and station A By recognizing two pieces of information of the transmission path type indicating the connected transmission path, the communication from the station B or D is not accepted.

[0007]

As described above, in the conventional data communication system, the type of transmission line and the station number are used to identify the station that has transmitted data. In a network to which a plurality of transmission paths 41, 42, 43, 44, and 45 are connected, it is necessary to recognize the transmission path of received data using the transmission type and the station number. Therefore, the transmission data includes not only the transmission path type of the transmission source station (information indicating the transmission path connected to the transmission source station) and the station number, but also the transmission path type indicating each transmission path that relays the transmission data, Also, information such as the station number of the relay station is required, and the amount of information becomes very large.

For example, as shown by a thick line in FIG.
When data is transmitted from station A to station K, the transmitted data is sent to station K via station A transmission line 41, station B transmission line 42, station F transmission line 45, station J transmission line 46, and so on. Must be notified to the station K.

Further, when a new transmission line is added, a process for recognizing a transmission line type indicating the transmission line must be added. As described above, in the conventional data communication method using only the conventional transmission line type and the station number, the amount of information increases when a series of data is transmitted in a plurality of times in a network in which a plurality of transmission lines are connected. There is a drawback that the communication efficiency is reduced and the time required for the processing is increased. Further, when a new transmission path is added to the network, processing for recognizing the transmission path must be added, which is inconvenient when expanding the system.

According to the present invention, in a network having a plurality of transmission paths, continuous communication of a series of exclusive communication data between any two stations is performed by using a receiving station (frame) with a small amount of information. It is an object of the present invention to realize a data communication system which enables a receiving station) to easily and quickly recognize a target frame.

[0011]

FIG. 1 is a diagram illustrating the principle of the present invention. The present invention relates to a data communication method between respective stations in a network having a plurality of LANs .
As shown in FIG. 3A, the receiving station 3 which has received the command 2 for instructing the start of exclusive data communication from the transmitting station 1 on an arbitrary LAN receives the command 2 from the transmitting station 1 as shown in FIG. Until the command 4 instructing the end of the exclusive data communication is received, data processing is performed only on the frame 5 in which the exclusive data 5a is set as shown in FIG.

In this case, the code designation of the exclusive data 5a is performed on the receiving station 3 side, for example, as described in claim 2.

[0013]

When an arbitrary station (receiving station) 3 receives a command 2 for instructing the start of exclusive data communication from another arbitrary station (transmitting station) 1, every time a frame is received thereafter, the receiving station 3 receives the command 2. It is determined whether or not the exclusive data 5a is set in the frame, and only the frame 5 in which the exclusive data 5a is set is received and processed, and the data processing is performed on the frame in which the exclusive data 5a is not set. Are continued until a command 4 instructing the end of exclusive data communication is received from the transmitting station 1.

Therefore, a series of communication data can be continuously and exclusively transmitted from the transmitting station 1 to the receiving station 3 in a plurality of frames, excluding communication from other stations.

[0015]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a diagram showing a system configuration of a network to which the embodiment is applied. FIGS. 3 and 4 show formats of a transmission frame (transmission data) and a response frame (response data) for communication between stations (stations). FIG.

The network shown in FIG.
Stations A and B are connected to the transmission line 101, stations B and C are connected to the transmission line 102, and stations B, D and E are connected to the transmission line 103. I have.

In the network having the above configuration, the stations A, B, C and D are connected to the transmission lines 101 and 10 respectively.
The communication with the station E is performed via the communication 2 and 103. The processing notification to the station E in these communications is made by the command 2 in the transmission data section 220 of the transmission frame shown in FIG.
21.

The command 221 is data for designating processing to be performed on the receiving station, and includes, for example, instructions for data read / write, program read / write, station start / stop, and the like. The interface is a command for releasing the interlock set and in data lock which is a command for locking the transmission data from other stations in the station on the reception side from the transmitting side of the station as a feature of this embodiment There is an unlock command.

For example, when a station receiving the command is executing the program read / write, the program is transmitted / received to prevent another station from writing / changing the program. The transmitting station transmits the interlock set command to the receiving station before transmitting the program read / write command, and the receiving station returns a response (response) indicating the end of the program read / write processing. Then, by transmitting an interlock release command to the receiving station, the receiving station reads / writes the program.
While writing, commands received from other stations are not processed.

Here, the configuration of the transmission frame shown in FIG. 3 will be described. The transmission frame is transmitted to the first communication control unit 210,
The first communication control unit 210 includes a transmission data unit 220 and a second communication control unit 230. The first communication control unit 210 transmits the destination station number data 21 indicating a destination station of the transmission frame.
1. Source station number data 212 indicating the source station that transmitted this frame, and frame data number 2 indicating the entire length (for example, the number of octets) of the transmission frame
13 Further, the transmission data section 220 stores the subsequent processing data storage area 2 in the transmission data section 220.
Notify processing method of data stored in 24 (command)
A command area 221 for setting the command which is data to be transmitted, an exclusive data area 223 for setting / resetting exclusive data indicating that this transmission frame is a part of a continuous frame to be exclusively processed, It comprises a data number set area 223 in which the number of data (for example, the number of octets) stored in the processing data storage area 224 is set. Then, the second communication control unit 230 transmits an FCS (Frame Check Sequence), which is data for checking whether the data of the transmission frame is normal / abnormal.
nce) 231 and END data 232 which is information (code) indicating the end of the frame.

Next, the configuration of the response frame shown in FIG. 4 will be described. The response frame also includes the first communication control unit 310, the transmission data unit 320, and the second
And a communication control unit 330.

The first communication control unit 310 includes destination station number data 311 indicating the station number of the station to which the response frame is transmitted, and source station number data indicating the station number of the station from which the response frame was transmitted. 312, the number of frame data 313 indicating the overall length of the response frame (for example, the number of octets), and the like. Further, the transmission data unit 320 includes a command area 321 for setting a received command, and a result (normal or abnormal) of a command processing requested from the partner station by a transmission frame.
, An exclusive data area 323 for setting exclusive data when the interlock set command is received and resetting exclusive data when the interlock release command is received, and a response to the received command. Response data storage area 3 for setting data
25, a data number setting area 324 in which the number of data (for example, the number of octets) of response data stored in the response data storage area 325 is set. Further, the second communication control unit 330 transmits an FCS (Fram) which is data for checking whether the response frame is normal / abnormal.
e Check Sequence) 331 and END data 332 which is information (code) indicating the end of the response frame.

The FCS is composed of, for example, a CRC (Cyclic Redundancy Check) code of an arbitrary generator polynomial. The exclusive data set in the exclusive data areas 222 and 323 of the transmission frame and the response frame are individually assigned to each of the stations A, B, C, D and E, and are mutually exclusive among a plurality of stations at the same time. Even when the data communication is performed, the receiving station can surely recognize the frame directed to the own station by referring to the exclusive data set in the transmission frame. The reset value of the exclusive data is commonly used by the stations A, B, C, D, and E, for example, “FF”.
_H "or" 00 _H "(H symbols indicate the hexadecimal value) using a unique value, such as.

Next, the operation when the station A communicates with the station E and the station A transfers a program to the station E in the embodiment having the above configuration will be described. (1) Normally, the stations A, B, C, and D transmit the exclusive data areas 222 and 32 of the transmission frame and the response frame.
No. 3 is reset and communication with the station E is performed without setting exclusive data. (2) When the station A attempts to transfer the program data (write the program) to the station E, first, the station number of the station E is transmitted to the destination station number data 211 and the station number of the source station is transmitted to the source station number data 212. A transmission frame having the format shown in FIG. 3 in which the station number of the station, that is, the station A, and an interlock set command are set in the command area 221 is created, and the transmission frame is transmitted via the transmission path 101, the station B, and the transmission path 103. To the station E. (3) Upon receiving the transmission frame, the station E analyzes the transmission frame and recognizes that the interlock set command has been transmitted from the station A. Then, the station number of the station A is contained in the transmission destination station number data 311 of the response frame shown in FIG.
A response frame shown in FIG. 4 in which the station number of the exclusive station is further set in the exclusive data area 323 and unique exclusive data composed of an arbitrary code and assigned to the own station, and the response frame is transmitted to the transmission line 103, A reply is sent to the station A via the station B and the transmission path 101. (4) Station A receives the above response frame,
Upon recognizing that the exclusive data set by the station E is set in the exclusive data area 323 of the response frame, the same exclusive data as the exclusive data is set in the exclusive data area 222, and the command The program write command is set in the area 221, the program data to be transmitted to the processing data storage area 224 is set, the data number (byte number) of the program is set in the data number set area 223, the destination station number data 211, the source station number A transmission frame having the format shown in FIG. 3 in which the station numbers of the stations A and E are set in the data 212 is created, and the transmission frame is transmitted to the transmission line 1
01, the station B, and the station E via the transmission path 103. (5) When the station E receives the interlock set command in the above process (3), every time a frame is received thereafter, the station E stores itself in the exclusive data area 222 of the frame in the above process (4). It is determined whether or not the exclusive data set in the exclusive data area 323 of the response frame is set. If the exclusive data is set, it is recognized that the frame is transmitted from the station A, and the transmission is performed. Frame processing data area 22
4 is read. Then, after reading the program, a response frame in the format shown in FIG. 4 in which response data for the received frame is set in the response data storage area 325 is created,
The response frame is transmitted to the station A via the transmission path 103, the station B, and the transmission path 101. On the other hand, if the exclusive data is not set, it is determined that the frame is transmitted from a station other than the station A, and the processing for the received frame is not performed. (6) Upon receiving the response frame from the station E, the station A creates a transmission frame of the format shown in FIG. 3 in which the next program data is stored in the processing data storage area 224, and transmits the transmission frame to the transmission line 10
1. Transmit to station E via station B and transmission path 103. (7) The station E recognizes the transmission frame from the station A in the same manner as the processing (5), reads the program data from the processing data storage area 224 of the transmission frame, and performs the same processing as the processing (5). Transmits a response frame to the station A. (8) The above processes (6) and (7) are repeated until station A transmits all program data to station E. Then, when the station A determines that the last program data has been transmitted, the station A next transmits the command area 22.
A transmission frame addressed to the station E in which the interlock release command is set to 1 is created, and the transmission frame is transmitted to the station E via the transmission path 101, the station B, and the transmission path 103. (9) When the station E receives the transmission frame in which the interlock release command transmitted from the station A is set, the exclusive data area 323 in which the exclusive data is reset and the response data corresponding to the interlock release command are received. Is set in the response data storage area 325, and the response frame is
03, station B, and reply to station A via transmission path 101. (10) When the station A receives the response frame from the station E and recognizes that the exclusive data in the exclusive data area 323 of the response frame has been reset, the station A thereafter transmits the exclusive frame in the transmission frame to be transmitted. The exclusive data in the exclusive data area 222 is reset. (11) Thereafter, the stations A, B, C, and D can communicate with the station E again at random.

As described above, the exclusive data area 222 for setting exclusive data in the transmission frame and the response frame,
By making use of two commands, an interlock set and an interlock release, for making a communication and excluding data transmitted from another station exclusively between the two stations, two stations are used. Between the stations (in the above embodiment, between the station A and the station E), a series of continuous data transmitted in a plurality of times is continuously and exclusively transmitted and received without being interrupted by transmission data from another station. it can. For this reason, adding the information amount of the frame by one data only requires 2 frames.
Exclusive communication can be performed between two stations. Moreover, in this case, the target data can be immediately recognized only by determining whether or not the exclusive data is set, so that the continuous data can be transmitted and received at a high speed. Further, even when a new transmission path is added, continuous data can be transmitted and received in the same sequence, and the system is excellent in expandability.

The above embodiment is an example of executing a program write command (where station A writes a program to station E).
Command can be executed using exclusive data in the same manner as in the above-described program write. In addition, the present invention can be applied to all data communications that require continuous transfer of data between any two stations, excluding communications from other stations, in addition to the above two commands. .

In this embodiment, the exclusive data is designated by the receiving station (receiving station). However, the exclusive station may be designated by the transmitting station (transmitting station). Good (for example, specified by the transmission frame of the interlock set command). In this case, if exclusive data is individually assigned to each station, the receiving station can surely recognize only the frame.

[0028]

According to the present invention, in exclusive data communication between two stations, a receiving station recognizes a target frame by determining whether or not exclusive data is set in a received frame. Therefore, the receiving station can easily recognize the target frame and perform data processing. Therefore, exclusive data communication between the two stations can be performed at high speed. Further, even when a new station is connected to an arbitrary transmission line, there is no need to change the protocol, so that the system is excellent in expandability. Further, since the frame configuration only needs to add the exclusive data area, the data communication efficiency is remarkably improved as compared with the related art. In addition, the above effects improve the throughput of the entire system. This effect becomes more remarkable as the scale of the network increases with the number of transmission paths.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a configuration diagram of a system to which an embodiment of the present invention is applied.

FIG. 3 is a diagram showing a format of a communication frame.

FIG. 4 is a diagram showing a format of a response frame.

FIG. 5 is a diagram illustrating two configuration examples of a conventional network and a method of exclusive data communication in those networks.

FIG. 6 is a diagram illustrating another configuration example of a conventional network and a method of exclusive data communication in the network.

[Explanation of symbols]

1 transmitting station 2 command (exclusive communication start command command) 3 receiving station 4 frames (exclusive communication end command command) 5 commands

Continuation of front page (56) References JP-A-60-217446 (JP, A) JP-A-60-203037 (JP, A) JP-A-57-50044 (JP, A) JP-B-62-45573 (JP, A) , B1) Fuji Tohoku Vol. 58, No. 2, 1985, Chihiro Nakajima et al., “MICREX-F Series Network System”, pages. 148-151 (58) Field surveyed (Int. Cl. ⁶ , DB name) H04L 12/28 H04L 29/04 JICST file (JOIS) WPI (DIALOG)

Claims (2)

(57) [Claims] A command (2) for instructing a transmission station (1) on an arbitrary control LAN to start exclusive data communication in a data communication method between stations in a network having a plurality of control LANs. Another received
The receiving station (3) on the control LAN is transmitted from the transmitting station (1) until receiving the command (4) instructing the end of the exclusive data communication from the transmitting station (1).
Frame exclusive data (5a) is set that (5)
Only the data set in the frame (5).
Data communication system, wherein only performing data processing on data. 2. The data communication system according to claim 1, wherein the code specification of the exclusive data (5a) is performed on the receiving station (3) side.