JPH04280529A - Data communication system - Google Patents

Abstract

PURPOSE:To allow a reception station to easily recognize an object frame at a high speed while using a frame of a small quantity of information with respect to the data communication system in which a series of data comprising plural frames is communicated exclusively between two stations in a network having plural transmission lines. CONSTITUTION:In the exclusive data communication, a station A sends at first an interlock set command to a station E. Then the station E returns a reply frame in which an exclusive data is set. The station A receiving the frame uses the frame in which an exclusive data is set sends a series of data continuously. The station E processes the data as to the frame in which an exclusive data is set among reception frames. When all the data transmission is finished, the station A sends the interlock release command and then the station E returns the reply frame in which an exclusive data is reset to the station A.

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 in a network having a plurality of transmission paths, and more particularly to a data communication system in which a series of data is divided into a plurality of frames and is exclusively communicated between two stations.

0002

[Prior Art] LAN (Local Area Network:
In networks such as local area networks, multiple devices (hereinafter referred to as stations) such as workstations and personal computers are connected over a single transmission line (consisting of twisted pair wires, coaxial cables, optical fibers, etc.). Connected. In addition, in a large-scale LAN with a large number of stations, multiple transmission paths are connected to each other via repeaters, etc.
Configure AN.

By the way, in the above-mentioned computer network, when data communication is performed between stations connected on the same or different transmission paths, there are restrictions on the number of data in a transmission frame, and there are restrictions on the number of data transmitted from the destination station. Due to constraints such as the size of the receive buffer, one piece of data may have to be divided into multiple frames and communicated multiple times. At this time, if the data is shared data between stations, communications from other stations must be excluded while a series of communications of that data is being performed.

In such cases, conventionally, the receiving station determines whether or not the data is part of a series of communication data.
If it is part of a series of communication data, the source station of the data, the transmission path type of the communication data (information indicating the transmission path to which the source station is connected),
It is recognized based on the station number (identification number assigned to the source station), etc., and from then on, only the transmitted data from the source station with the same transmission line type and station number, etc. is processed, and other Even if the data transmitted from the station was received, the data was not accepted.

An example of such data communication is shown in FIG.
, (B). First, Figure 5 (A
) In a network where four stations A, B, C, and D are connected to one transmission path 21 as shown in FIG. In order for C to be able to recognize which station A, B, or D transmitted the received data, it only needs to know the station number of the transmitter.

[0006] Furthermore, there are two transmission lines 31 and 32 as shown in FIG. In a network where station D is connected to transmission path 32, station D and stations A and B are connected to different transmission paths, so if station D is assigned the same station number as station A or B, There is. therefore,
Transmission path type information is required to identify the transmission path 31 or 32 to which the source station is connected. Therefore, when station A sends a series of data to station C multiple times, if station C wants to exclude communications from stations other than station A, the station number of station A and station A Two pieces of information, the transmission path type indicating the connected transmission path, were recognized and communications from stations B or D were not accepted.

[0007]

[Problems to be Solved by the Invention] As mentioned above, in the conventional data communication system, the transmission path type and station number are used to recognize the station that has transmitted data. In a network in which a plurality of transmission lines 41, 42, 43, 44, and 45 are connected, it is necessary to also recognize the transmission route of the received data using the transmission type and the station number. Therefore, the transmission data includes not only the transmission path type of the source station (information indicating the transmission path to which the source station is connected) and station number, but also the transmission path type indicating each transmission path that relayed the transmission data, In addition, information such as the station number of the relay station is required, and the amount of information becomes extremely large.

For example, as shown by the thick line in FIG.
When transmitting data from station A to station K, the transmitted data is sent via ■Station A■Transmission line 41■Station B■Transmission line 42■Station F■Transmission line 45■Station J■Transmission line 46 In order to send the information to station K, the above information ① to ② must be notified to station K.

Furthermore, when a new transmission path is added, it is necessary to add processing for recognizing the transmission path type indicating the new transmission path. In this way, with the conventional data communication method that uses only the conventional transmission path type and station number, the amount of information increases when a series of data is divided into multiple transmissions in a network where multiple transmission paths are connected. This method has disadvantages in that communication efficiency decreases and the time required for processing increases. Furthermore, 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.

[0010] The present invention enables continuous communication of an exclusive series of communication data between arbitrary two stations in a network having a plurality of transmission paths, while using frames with a small amount of information. The purpose of the present invention is to realize a data communication system that allows a receiving station (station on the receiving side) to easily and quickly recognize a target frame.

[0011]

[Means for Solving the Problems] FIG. 1 is a diagram illustrating the principle of the present invention. The present invention is a data communication system between stations in a network having a plurality of transmission paths, in which a command 2 instructing the start of exclusive data communication is received from an arbitrary transmitting station 1, as shown in FIG. receiving station 3
The exclusive data 5a is set as shown in (B) of the same figure until command 4 instructing the termination of the exclusive data communication is received from the transmitting station 1 as shown in (C) of the same figure. Data processing is performed only on frame 5.

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

[0013]

[Operation] When an arbitrary station (receiving station) 3 receives a command 2 instructing the start of exclusive data communication from another arbitrary station (transmitting station) 1, the received It is determined whether or not the exclusive data 5a is set in the frame, and only the frames in which the exclusive data 5a is set are accepted and data processed, and the exclusive data 5a is set in the frame.
The operation of not performing data processing for frames for which a is not set is continued until command 5 is received from the transmitting station 1 to instruct the end of exclusive data communication.

Therefore, it is possible to continuously and exclusively transmit a series of communication data divided into a plurality of frames from the transmitting station 1 to the receiving station 3, excluding communications from other stations.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a system configuration diagram of a network to which the embodiment is applied, and FIGS. 3 and 4 respectively show transmission frames (transmission data) communicated between each station.
, is a diagram showing the format of a response frame (response data).

The network shown in FIG. 2 has a transmission path 101
, 102, and 103, 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, B, and C are connected to the transmission line 103.
D and E are connected.

In the network configured as described above, stations A, B, C, and D are connected to each of the transmission lines 101 and 102.
, 103 to communicate with station E. Processing notifications to station E in these communications are made using the command 22 in the transmission data section 220 of the transmission frame shown in FIG.
1.

The command 221 is data that specifies processing to be performed on the receiving station, and includes, for example, commands to read/write data, read/write programs, start/stop the station, and the like. The features of this embodiment include an interlock set, which is a command from the sending station to the receiving station to lock transmission data from another station, and an interlock set, which is a command to release the ink lock. There is a release command.

For example, regarding program read/write, while the station that received the command is executing the program read/write, in order to prevent other stations from writing or changing the program, The side station sends the above interlock set command to the receiving station before sending the program read/write command, and the receiving station returns a response indicating that the program read/write process has been completed. Thereafter, by transmitting an interlock release command to the receiving station, commands received from other stations are not processed while the receiving station is reading/writing the program.

The structure of the transmission frame shown in FIG. 3 will now be explained. The transmission frame is transmitted by the first communication control unit 210,
It consists of a transmission data section 220 and a second communication control section 230, and the first communication control section 210 receives destination station number data 211 indicating the destination station of this transmission frame.
, transmission station number data 212 indicating the source station that transmitted this frame, and frame data number 213 indicating the entire length (for example, number of octets) of this transmission frame.
It consists of. The transmission data section 220 also includes a command area 221 in which the above-mentioned command, which is data that notifies (instructs) how to process data stored in the processing data storage area 224 that follows in this data section 220, is set.
, an exclusive data area 223 in which exclusive data is set/reset indicating that this transmitted frame is part of a continuous frame to be processed exclusively, and is stored in the processed data storage area 224. Data number set area 22 where the data number (for example, the number of octets) is set
It consists of 3rd class. Then, the second communication control unit 230
is FCS (Frame Check
Sequence) 231 and END data 232 which is information (code) indicating the end of the frame.

Next, the structure of the response frame shown in FIG. 4 will be explained. Like the transmission frame, the response frame also includes a first communication control section 310, a data section 320, and a second communication control section 330.

The first communication control unit 310 receives destination station number data 311 indicating the station number of the station to which this response frame is transmitted, and source station number data 311 indicating the station number of the source station that transmitted this response frame. 312, the number of frame data 313 indicating the overall length (for example, number of octets) of the response frame, and the like. The data section 320 also includes a command area 321 for setting the received command, termination information 322 indicating the result (normal or abnormal) of the command processing requested by the other station in the transmission frame, and the interlock set command. an exclusive data area 323 in which exclusive data is set when the interlock release command is received, and the exclusive data is reset when the interlock release command is received; a response data storage area 325 in which response data to the received command is set;
, a data number setting area 324, etc., in which the number of response data (for example, the number of octets) stored in the response data storage area 325 is set. Further, the second communication control unit 330 uses FCS (Fram
e Check Sequence) 331 and END data 332 which is information (code) indicating the end of this response frame.

[0023] By the way, the above FCS is a CRC (Cyclic Redund-and-
cy Check) code. In addition, exclusive data areas 222 and 32 for transmission frames and response frames
The exclusive data set to 3 is for each station A and B.
, C, D, and E, and even if exclusive data communication is performed between multiple stations at the same time,
The receiving station is able to reliably recognize the frame intended for its own station by referring to the exclusive data set in the transmitted frame. Note that the reset value of exclusive data is for each station A, B, C,
D and E are common, for example, “FFH” or “00H”
” (H is a symbol indicating a hexadecimal value).

Next, the operation when station A communicates with station E and station A transfers a program to station E in the embodiment with the above configuration will be described. (1) Normally, stations A, B, C, and D use the exclusive data area 222 of the transmission frame and response frame,
323 and communicates with station E without setting exclusive data. (2) When station A attempts to transfer program data (write program) to station E, first the station number of station E is written in the destination station number data 211, and the station number of station E is written in the source station number data 222. A transmission frame with the format shown in FIG. 3 is created in which the station number of the station, that is, station A, and an interlock set command is set in the command area 221, and the transmission frame is transmitted via the transmission path 101, station B, and transmission path 103. and transmits it to station E. (3) Upon receiving the above transmission frame, station E analyzes the transmission frame and sends it to station A.
Recognizes that an interlock set command has been sent from. Then, the destination station number data 311 of the response frame shown in FIG. A response frame shown in FIG. 4 is created in which exclusive exclusive data previously assigned to the own station is set, and the response frame is sent back to station A via transmission path 103, station B, and transmission path 101. (4) When station A receives the response frame and recognizes that the exclusive data set by station E is set in the exclusive data area 323 of the response frame, station A reads the same data as the exclusive data. Exclusive data is set in the exclusive data area 222, the program write command is sent to the command area 221, the program data to be sent to the processing data storage area 224 is set, and the number of data (number of bytes) of the program is set in the data number set area 223. ), and also set destination station number data 211,
A transmission frame in the format shown in FIG. 3 is created in which the station numbers of station A and station E are set in the source station number data 212, respectively, and the transmission frame is sent to station E via transmission path 101, station B, and transmission path 103. Send. (5) When station E receives the interlock set command in the above process (3), every time it receives a frame thereafter, it writes data to the exclusive data area 222 of that frame to the station A in the process (4) above. It is determined whether or not the exclusive data set in the exclusive data area 323 of the response frame is set, and if the exclusive data is set, the frame is recognized as being transmitted from station A, and the transmission The program data stored in the processing data area 224 of the frame is read. After reading the program, the response data for the received frame is stored in the response data area 32.
A response frame is created in the format shown in FIG. On the other hand, if the above exclusive data is not set,
It is determined that the frame is transmitted from a station other than station A, and no processing is performed on the received frame. (6) When station A receives the response frame from station E, it creates a transmission frame in the format shown in FIG. , station B, and to station E via transmission line 103. (7) Station E recognizes the transmission frame from station A in the same manner as in process (5) above, and
The program data is read from the processing data storage area 224 of the transmission frame, and a response frame is transmitted to station A in the same manner as in process (5) above. (8) The above processes (6) and (7) are performed at station A.
is repeated until all program data has been sent to station E. When station A determines that it has transmitted the final program data, it then creates a transmission frame addressed to station E with an interlock release command set in the command area 221, and sends the transmission frame to transmission line 101, station B, and transmits to station E via transmission line 103. (9) When station E receives the transmission frame in which the above-mentioned interlock release command is set, which was sent from station A, station E stores the exclusive data area 323 in which the exclusive data has been reset and the response data corresponding to the above-mentioned interlock release command. A response frame is created in which the response data area 325 is set, and the response frame is sent back to station A via transmission path 103, station B, and transmission path 101. (10) When station A receives the response frame from station E and recognizes that the exclusive data in the exclusive data area 323 of the response frame has been reset, station A will no longer use that response frame in subsequent transmission frames. The exclusive data in the exclusive data area 222 is reset. (11) After that, stations A, B, C, and D can communicate with station E again at random.

In this way, the exclusive data area 222 sets exclusive data in the transmission frame and the response frame.
323, and furthermore, by using two commands, interlock sec and interlock release, to perform communication between two stations exclusively excluding data sent from other stations, any two stations can (in the above embodiment, between station A and station E), a series of continuous data to be transmitted in multiple parts is continuously and exclusively transmitted and received without being interrupted by data transmitted from other stations. can. Therefore, by simply adding one piece of information to the frame, exclusive communication can be performed between two stations. Moreover, in this case, the target data can be immediately recognized just by determining whether or not exclusive data is set, so that continuous data can be sent and received at high speed. Furthermore, even when a new transmission path is added, data can be continuously transmitted and received in the same sequence, making the system highly expandable.

The above embodiment is an example in which a program write command (station A writes a program to station E) is executed, but a program read command (for example, station A writes a program to station E) is executed.
The command (to read a program from) can also be executed using exclusive data in the same way as the program write mentioned above. In addition to the above two commands, the present invention can be applied to all data communications that require continuous data transfer between any two stations, excluding communications from other stations. .

Furthermore, in this embodiment, the receiving station (receiving station) specifies exclusive data, but even if the transmitting station (transmitting station) specifies exclusive data, (For example, specify in the transmission frame of the above interlock set command). In this case, by individually allocating exclusive data to each station, the receiving station can reliably recognize only the relevant frame.

[0028]

According to the present invention, in exclusive data communication between two stations, the receiving station recognizes the target frame by determining whether exclusive data is set in the received frame. Therefore, the receiving station can easily recognize the target frame and process the data. Therefore, exclusive data communication between two stations can be performed at high speed. Furthermore, even when a new station is connected to an arbitrary transmission path, there is no need to change the protocol, so the system has excellent expandability. Furthermore, since the frame configuration requires only the addition of an exclusive data area, data communication efficiency is significantly improved compared to the conventional method. Furthermore, the above effect improves the throughput of the entire system. This effect becomes more pronounced as the network becomes larger and has more transmission paths.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining 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 the format of a communication frame.

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

FIG. 5 is a diagram illustrating two configuration examples of conventional networks and a method of exclusive data communication in these 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) 3 Receiving station 4 Command

Claims (2)

[Claims] Claim 1: In a data communication system between stations in a network having a plurality of transmission paths, a receiving station (1) receives a command (2) instructing to start exclusive data communication from an arbitrary transmitting station (1). 3) performs data processing only on the frame (5) in which the exclusive data (5a) is set until the command (4) instructing the termination of the exclusive data communication is received from the transmitting station (1). A data communication method characterized by: 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.