JPH06125348A - Communication controller - Google Patents

Abstract

PURPOSE:To eliminate the need for recognition of an address of communication destination by communicating a communication frame representing a connection request return when a logic port number and a line connection request key name are coincident. CONSTITUTION:When line connection is awaited, a service request means 1 makes a request of line connection comprising at least a logic port number, a line connection wait and a key name representing the line connection wait and stores information in a line connection buffer 2. A communication station going to make communication uses a broadcast means 3 to broadcast a communication frame representing a communication connection request on a communication line. The communication station of an opposite party receives a communication frame and a discrimination means 4 discriminates the coincidence between a line connection request key name and a logic port number stored in its own buffer means 2. When they are coincident with each other, a connection request means 5 sends a station address and a broadcast means permits a connection request and the communication is started. Then the line is connected without being conscious of the address of the opposite party.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system for communicating between a plurality of communication stations connected to a multi-drop type communication line (local area network: LAN). The present invention relates to a communication control device that enables a station to communicate without being aware of the address of the other communication station.

[0002]

2. Description of the Related Art Conventionally, there have been the following methods for communication between a plurality of communication stations connected to a multi-drop communication line. (A) The transmission / reception is executed by designating the address assigned to the communication destination station of the other party. (B) A logical line is established between two communication stations to execute transmission / reception.

Here, as a method of establishing a logical line,
At the partner communication station, a listening (Listen) for line connection is performed, and the other communication station is listening to the partner communication station.
It is realized by making a connection request.

[0004]

By the way, in any communication control device according to such a method, it is necessary to be aware of the communication station of the other party. Therefore, in the case of constructing a communication system by arranging communication stations in a distributed manner, it is possible to flexibly deal with the case where the communication station of the other party to be coupled to the communication line is frequently changed or not determined. There was a problem that I could not do it.

The present invention has been made in view of the above circumstances, and is for establishing a logical line in a communication system for communicating between a plurality of communication stations connected to a multi-drop type communication line. An object of the present invention is to provide a communication control device that enables communication to be realized by broadcasting and allows communication without being aware of the address of the communication destination.

[0006]

SUMMARY OF THE INVENTION The present invention which achieves such an object is, in a communication system for communicating between a plurality of communication stations connected to a multi-drop type communication line, a line to each communication station. When waiting for connection, the line connection wait request consisting of at least the logical port number, the key name indicating the line connection wait, and the key name indicating the line connection request is output, and the line connection is actively performed.
Service request means for outputting a line connection request consisting of at least a logical port number, a key name indicating a line connection wait, and a key name indicating a line connection request, and a request received from the service request means and included in the request. A line connection control buffer means for storing information and a communication frame showing a line connection request including a logical port number and a line connection request key name based on the line connection request from the service requesting means. And a communication frame indicating a line connection request sent via a communication line, and the logical port number and the line connection request key name included in the communication frame are stored in the own line connection control buffer means. Judgment means to judge whether the stored logical port number matches the line connection request key name, and this judgment When it is determined that the logical port number and the line connection request key name match in the step, a communication frame indicating a connection request reply including at least the station address of itself, the logical port number, and the key name indicating the line connection waiting is displayed. One that matches the connection request replying means that is sent out on the communication line and the key name that indicates the line connection wait included in the communication frame that received the communication frame indicating the connection request reply returned via the communication line Second broadcasting of a communication frame indicating the connection request permission including the selected partner station address selected on the communication line
When the communication frame indicating the line connection request permission is received via the broadcast means and the communication station and the selected station address included in the communication frame is its own station address, the communication frame indicating the response to the connection permission is transmitted. It is a communication control device configured to include a connection permission reply means for sending out on a line.

[0007]

The communication station attempting to communicate first broadcasts the communication frame indicating the communication connection request on the communication line by the first broadcasting means. On the other hand, the communication station waiting for the line connection
When a communication frame showing a communication connection request broadcast on a communication line is received and the logical port number and the line connection request key name match, at least the station address, logical port number, and line connection waiting key. A communication frame indicating a connection request reply including a name and the like is returned to the communication station that is going to communicate.

The communication station trying to communicate is
One or more communication frames indicating such a connection request reply are received, and one of them whose key name matches the key name requested by the service request means is selected, and the station to be connected is selected. This is broadcast by the second broadcast means. The selected communication station receives the broadcasted communication frame indicating the connection request permission, sends out the communication frame indicating the connection permission reply, and completes the connection of the logical line.

As a result, the communication station attempting to perform communication first receives the transmission destination (destination) when the line is connected.
It becomes unnecessary to be aware of the station address of.

[0010]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a conceptual diagram showing the construction of an embodiment of the present invention. In the figure, BS is a multi-drop communication line (local area network; LAN), ST1, S
T2 ... are a plurality of communication stations connected to the communication bus BS so as to be distributed and have a bus interface 11 that functions as an interface to the communication line BS of the multi-drop system.

In each of the communication stations ST1, ST2, ..., 1 is a service requesting means which collectively indicates the tasks requiring communication by various applications. When waiting for line connection, at least the logical port number and line connection wait When a line connection waiting request consisting of a key name indicating the line connection request and a key name indicating the line connection request is output and the line connection is actively performed, at least the logical port number, the key name indicating the line connection wait, and the line connection A line connection request consisting of a key name indicating the request is output.

A line connection control buffer means 2 receives a request signal from the service request means 1 and receives each information (logical port number, key name indicating line connection waiting, and line connection request) contained in each request. Key name indicating) is stored. Reference numeral 3 is a first broadcast means for broadcasting a communication frame indicating a line connection request including a logical port number and a line connection request key name on the communication line BS based on the line connection request from the service request means 1. Is configured.

Reference numeral 4 is a judging means, which receives a communication frame indicating a line connection request sent from the first broadcasting means via the communication line BS, and a logical port number and a line connection request key included in the communication frame. It is to judge whether the name matches the logical port number stored in the line connection control buffer means 2 of itself and the line connection request key name.

Reference numeral 5 denotes a connection request returning means, which indicates at least its own station address, logical port number, and line connection waiting when the judgment means 4 judges that the logical port number and the line connection request key name match. A communication frame indicating a connection request reply including a key name and a communication line BS
Send to the top. Reference numeral 6 denotes a second broadcasting means, which receives a communication frame indicating a connection request reply returned via the communication line BS, and selects one key name matching the line connection waiting included in the communication frame. Then, the communication frame indicating the connection request permission including the selected partner station address is broadcast on the communication line BS.

Reference numeral 7 is a connection permission reply means, which receives a communication frame indicating permission of a line connection request via the communication line BS,
When the selected station address included in the communication frame is its own station address, a communication frame indicating a reply to the connection permission is sent to the communication line BS. Here, the above-mentioned first and second broadcasting means 3 and 6, the judging means 4, the connection request returning means 5 and the connection permission returning means 7 are programs for controlling the connection of the logical line (logical line control task). It can be realized by 8.

FIG. 2 is a structural conceptual diagram of the line connection control buffer means 2. Reference numeral 21 is a line connection request control buffer used when a line connection request is made, and 22 is a line connection waiting control buffer used when a line connection wait request is made. Managed. Here, the configuration is shown only on the line connection request control buffer 21 side.

The inside of the line connection request control buffer 21 is composed of a logical port control buffer 20 managed for each logical port number # 1 to #N. Further, in each logical port control buffer 20, a plurality of line control buffers 23 managed by the lines # 1 to #N are provided for each line connection request.
Is provided. FIG. 3 is a conceptual diagram of the configuration in each logical port control buffer.

The header of the logical port control buffer 20 is provided with a storage area for a logical port number, a control buffer list during connection processing, and a connection completion control buffer list. Here, a storage area for a line connection request key name, a line connection waiting key name, and a partner station address is provided in the line control buffer created for each line connection request. FIG. 4 is a configuration diagram (format) of a communication frame (communication packet) transmitted on the communication line BS. It is assumed that this communication frame is created by the bus interface 11 based on the signal from the logical line control task 8.

Reference numeral 31 is an area (area) in which the type of communication frame is set. The types of communication frame for line connection control related to the present invention are as follows. It is prepared. Connection request notification: a communication frame for notifying all communication stations that a connection request has been made, and is sent from the first broadcasting means 3.

Connection request reply: a communication frame for replying that there is a connection wait for the connection request, which is sent from the connection request reply means 5. Connection permission notification: A communication frame for notifying all communication stations that the connection request has been selected and has been permitted, and is transmitted from the second broadcasting means 6.

Connection permission reply: A communication frame for confirming the connection permission, which is sent from the connection permission reply means 7. Reference numeral 32 is an area in which the destination station address indicating the destination of the communication frame is set. When all communication stations are addressed (broadcast),
For example, "*" indicating that is set here. Three
Reference numeral 3 is an area in which the source communication station address of the communication frame is set. 34 is an area for setting a logical port number, 35 is an area for setting a key name of a line connection waiting request, 36 is an area for setting a key name of a line connection request, and 37 is a side information necessary for the communication frame. The area.

The operation of how the logical line connection is carried out in the apparatus thus constructed will be described below. FIG. 5 is a conceptual configuration diagram of a communication system assumed in the following description. Here, for simplification of description, a case where three communication stations A, B, and C are connected to the communication line BS and communication is performed between the communication station A and the communication station B will be taken as an example.

FIG. 6 shows the communication line BS in this case.
It is an explanatory view showing a situation of a communication frame sequentially transmitted to. First, communication station A trying to communicate
The first broadcast means 3 of 1 broadcasts a communication frame indicating a connection request notification in the format as shown in FIG. 6A on the communication line BS based on the line connection request signal from the service request means 1. In this communication frame, the area 31 indicates “connection request notification” indicating the type of the communication frame, the area 32 indicates “*” indicating broadcast, and the area 33 indicates the address of the communication station of the sender. "A", area 34
Is set to the logical port number "100", the area 35 is set to the connection waiting key name "LISTEN", and the area 36 is set to the connection request key name "CONNECT". Therefore, prior to the communication, no consideration is given to the communication station address of the communication partner.

The communication frame of the format shown in (a), broadcast on the communication line BS, is transmitted to all the other communication stations B connected to the communication line BS.
Received together at C. When the communication station B on the side waiting for the connection of the line receives the communication frame indicating the above-mentioned line connection request broadcast on the communication line BS, the judging means 4 determines the logical port number "100" included in the communication frame. And the line connection request key name "CONN
ECT "determines whether the logical port number stored in its own line connection control buffer means 2 matches the line connection request key name.

If they match, the connection request returning means 5 designates "A" as the destination communication station for the communication frame indicating the connection request reply in the format shown in FIG. Send on the line BS. Similarly, communication station C on the side waiting for line connection
Also, a communication frame having a format as shown in (c) is sent to the communication line BS by designating "A" as the destination communication station. Here, in the communication frame indicating the connection request reply sent to the communication station A, as shown in (b) or (c), the station address (B or C) of the user and the logical port number "1" are set.
00 "and the key name" LISTEN "that indicates line connection waiting
Includes and.

The communication station A respectively receives the communication frames shown in (b) and (c) sent on the communication line BS. When receiving these communication frames,
The second broadcasting means 6 includes the key name “LISTE”, which is included in those communication frames and indicates the line connection waiting.
N "is confirmed to match, one of them, for example, the communication station" B "on the side that has received the communication frame indicating the connection request reply is selected, and the connection request including the selected partner station address" B "is selected. A communication frame having a format as shown in (d) indicating permission is broadcast on the communication line BS.

The connection permission reply means 7 of the communication station B, which has received this communication frame via the communication line BS,
Knowing that your communication station has been selected by the information set in area 37 in the communication frame,
To confirm the connection permission to communication station A,
A communication frame having a format as shown in (e) indicating a connection permission reply is sent to the communication line BS with the communication station A as the destination.

By the above procedure, the line connection between the communication station A and the communication station B is completed. At this time, the communication station C that has not been selected prepares for the next line connection request. FIG. 7 is a diagram showing the state of the logical port control buffer 20 created on the basis of the request signal from the service request means 1 in the associated communication station at each point in the procedure described above. (A) shows the state of the control buffer formed in the communication station A prior to sending the communication frame indicating the connection request notification.

When the line connection request from the service request means 1 is output, the logical port number # "10
The connection request key name "CONNECT" and the connection waiting key name "LIST" are newly added to the connection processing list (area) of "0".
Information of "EN" is stored and a control buffer is formed. At this time, the address of the partner communication station is not recognized at all. (B) shows the state of the control buffer in each of the communication stations B and C that has received the communication frame indicating the connection request notification broadcast on the communication line BS. Each communication station that has received the communication frame indicating the connection request notification receives the logical port number # "100" and the connection request key name "C" from the communication frame.
"CONNECT" and the connection waiting key name "LISTEN" are extracted. Then, the logical port number # “10
The connection waiting processing list is extracted from the own logical port control buffer corresponding to "0", and the connection request key name "CON
Search for "NECT".

As a result, when a matching connection request key name "CONNECT" is found in the connection waiting list, a communication frame indicating the connection request reply is sent to the communication station A which is the transmission source (the format of which is shown in FIG. b)) is returned. If no matching connection request key name "CONNECT" is found in the connection waiting list, nothing is done. (C) shows the state of the control buffer formed in the communication station A which has received the communication frame indicating this connection request reply. Upon receiving the communication frame indicating the connection request reply, the communication station A receives the logical port number # “100” and the connection request key name “C” from the communication frame.
"CONNECT" and the connection waiting key name "LISTEN" are extracted. Then, the logical port number # “10
The connection request processing list is extracted from the own logical port control buffer corresponding to "0", and the connection waiting key name "LIS
Search for "TEN".

As a result, when a matching connection waiting key name "LISTEN" is found in the connection request processing list, a communication frame indicating connection request permission indicating the selected communication station "B" (its format is as shown in FIG. 6). (D)
Broadcast). If no matching connection waiting key name “LISTEN” is found in the connection request processing list, nothing is done. (D) is the communication station B selected by the communication frame indicating the connection request permission.
3 shows the state of the control buffer formed by. Upon receiving the communication frame indicating the connection request permission, the communication station B, having learned that it has been selected, replaces the line control buffer in the connection waiting processing list with the connection completion list. After that, the communication frame (the format of which is shown in (e) of FIG. 6) indicating the connection permission reply is transmitted to the communication station A of the partner. (E) shows the state of the control buffer in the communication station A after receiving the communication frame indicating the connection permission reply. Upon receiving the communication frame indicating the connection permission reply, the communication station A replaces the line control buffer in the connection request processing list with the connection completion list.

By the above operation, a logical line is connected between the communication station A and the communication station B, and 1: 1 communication is possible between both communication stations.

[0033]

As described in detail above, according to the present invention, there is an effect that it is not necessary to be aware of the address of the partner communication station for connecting the line first. Therefore, the corresponding communication stations can be arbitrarily moved to each other for an application that requires communication in a 1: 1 relationship between a plurality of communication stations connected to the same communication line. In addition, when there are multiple communication stations as servers that execute a certain service on the same communication line, a logical line can be established without specifying the other party, and it seems that one server goes down. In any case, it is possible to easily switch to another server.

[Brief description of drawings]

FIG. 1 is a structural conceptual diagram showing an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing the configuration of line connection control buffer means.

FIG. 3 is a conceptual diagram of the configuration within each logical port control buffer.

FIG. 4 is a configuration diagram (format) of a communication frame (communication packet) transmitted on a communication line BS.

FIG. 5 is a conceptual diagram of a configuration of a communication system assumed in the description.

FIG. 6 is an explanatory diagram showing a state of communication frames sequentially transmitted to a communication line BS.

FIG. 7 is a diagram showing a state of a logical port control buffer created in an associated communication station at each time point of line connection.

[Explanation of symbols]

 BS communication line ST1, ST2 ... Communication station 11 Bus interface 1 Service request means 2 Line connection control buffer means 3 First broadcast means 4 Judgment means 5 Connection request reply means 6 Second broadcast means 7 Connection permission reply means

Claims (1)

[Claims] 1. In a communication system for communicating between a plurality of communication stations connected to a multi-drop communication line, each communication station waits for connection of the line, and at least a logical port number,
When a line connection wait request consisting of a key name indicating line connection wait and a key name indicating line connection request is output and the line connection is actively performed, at least the logical port number and the key name indicating line connection wait Service request means for outputting a line connection request consisting of a key name indicating a line connection request, a line connection control buffer means for receiving a request from the service request means and storing information included in the request, and a service request means A first broadcast means for broadcasting a communication frame indicating a circuit connection request including a logical port number and a circuit connection request key name on the basis of the circuit connection request from the communication line, and the communication frame is sent via the communication line. The communication frame indicating the line connection request is received, and the logical port number and line connection request key name included in the communication frame are Judgment means for judging whether the logical port number stored in the line connection control buffer means matches the line connection request key name, and this judgment means judges that the logical port number matches the line connection request key name. Connection request response means for sending out a communication frame indicating a connection request reply including at least its own station address, logical port number, and key name indicating line connection waiting to the communication line, and a reply via the communication line Received a communication frame indicating a connection request reply, select one of the key names in the communication frame that indicate the line connection wait, and select the communication frame that includes the selected partner station address and indicates the connection request permission. The second broadcasting means for broadcasting on the communication line and the permission of the line connection request through the communication line are shown. A communication including a connection permission reply means for transmitting a communication frame indicating a reply to the connection permission to the communication line when the selected station address included in the communication frame is the own station address. Control device.