JPH0523657B2 - - Google Patents

Description

[Detailed description of the invention] 〔table of contents〕 The present invention will be explained in the following order.

A. Overview B. Field of industrial application C. Prior art (Fig. 7) D. Problem to be solved by the invention E. Means for solving the problem (Fig. 1) F. Effect F _1. Expanded message format Explanation of (Fig. 2) F ₂ Effect of the present invention (Figs. 1 and 2) G Example (Figs. 3 to 6) G ₁ Description of configuration (Figs. 3 to 5) G ₂ Explanation of operation (Figures 3 to 6) H Effect A [Summary] In an online system where the number of addresses assigned to terminals is limited and the line control program can service one process at a time, the message header By expanding ``to include terminal addresses,'' it became possible to connect multiple terminals to a single line, exceeding the allocated number.

B [Industrial Application Field] The present invention is applicable to an online system in which the number of addresses assigned to a terminal is limited and a line control program can service one process at a time. This invention relates to a method for connecting multiple terminals to a single line.

C [Prior Art] Conventionally, when connecting a plurality of terminals to a single line, this was done by inserting an appropriate branching device on the line.

FIGS. 7A and 7B show a conventional method for connecting multiple terminals to a single line. Note that the line control program can service one transmission or reception process at a time.

FIG. 7A shows a system in which terminals Ta ₁ to _{Ta 3} are directly connected to host A _A by respective lines La ₁ to _{La 3} , in which a branching device Ba is provided on line La ₁ of terminal Ta ₁ , An example is shown in which terminal Ta ₄ is connected to this via line La ₄ .

In FIG. 7B, each terminal Tb ₁ to _{Tb 3} is connected to the terminal controller TCb by a respective line Lb ₁ to _{Lb 3} , and the terminal controller TCb and the host Hb are connected to a single line.
In a system connected by Lb ₀ ,
This shows an example in which a branching device Bb is provided on the line Lb ₃ of the terminal Tb ₃ , and the terminal Tb ₄ is connected to this via the line Lb ₄ .

A necessary condition for connecting a plurality of terminals to a single line using such a terminal connection method using a branching device is that the protocol used for communication allows the existence of a plurality of terminals.

For example, polling and selecting codes in asynchronous procedures include codes that indicate the terminal address, and SDLC (Synchronous Data
In high-level procedures such as Link Control),
A code indicating the terminal address is included in the frame's protocol header. Therefore, by including a plurality of these address codes, it is possible to connect a plurality of terminals to a single line. However, if there is a limit to the number of addresses allocated by the address code, it is not possible to connect terminals exceeding the allocated number.

Further, if the protocol does not allow the existence of multiple terminals, it is not possible to connect other terminals to a single line using a branching device. Figure 1C is
This figure shows an example of such an online system.

In FIG. 7C, each terminal Tc ₁ to _{Tc 3} is connected in series to the terminal control device TCc by a common loop line Lcp, and the terminal control device TCc and the host Hc are connected in series.
Connected by a single line Lco.

In this online system shown in Figure 7C,
Once a system protocol is established, increasing the number of terminals is not allowed since this would involve changing the protocol. Even if it were allowed, it would be extremely limited and difficult to implement in practice.

D [Problems to be solved by the invention] As mentioned above, in the conventional method of connecting multiple terminals to a single line, there is a limit to the number of addresses assigned to the terminals, including when the protocol does not allow the existence of multiple terminals. , there was a problem in that it was not possible to connect more terminals than the allocated number to a single line.

The present invention provides a method for connecting multiple terminals to a single line, which makes it possible to connect a number of terminals exceeding the assigned number to a single line even if there is a limit to the number of addresses assigned to the terminals. The purpose is to

F [Means for solving the problems] The means taken by the present invention to solve the above-mentioned problems in the conventional connection method of multiple terminals to a single line will be explained with reference to FIG. .

FIG. 1 shows the structure of the present invention in blocks.

In FIG. 1, 100 is a terminal device connected to the single line 200, which corresponds to each of the terminals Ta ₁ to _{Ta 3} , Tb ₁ to Tb ₃ , and Tc ₁ to Tc ₃ in FIG. 7 A, B, and C. The number of addresses assigned to the terminal device 100 is limited to a fixed number.

Reference numeral 110 denotes a line control means that controls the connection between the single line 200 and the line control layer section, and its line control program can provide services for one process, such as transmission or reception, at a time.

Terminals 120 ₁ to 120n include original terminals and newly connected subterminals.
In the description of the present invention, the original terminal and the sub-terminal are both referred to as a terminal without distinction.

130 is a process control table, and each terminal 12
A schedule for processing process requests such as transmission and reception requests generated from 0 ₁ to 120n and information necessary therefor are set.

140 is a line control layer unit that uses the process control table 130 to control each terminal 120 ¹ to 120n.
A schedule for processing each process requested by the process controller 130 is created and set in the process control table 130. If the process to be executed is a sending process, an extended message header containing the address of the terminal that issued the transmission request is added to the transmission message and passed to the line control program, and if the process to be executed is a receiving process, Performs the process of distributing the received message to the terminal whose address is included in the extended message header of the message.

F [Function] Before explaining the function of the present invention, the extended message format used in the present invention will be explained.

F ₁ (Explanation of extended message format) In order to avoid protocol restrictions and allow multiple terminals (as mentioned above, each terminal includes subterminals) to be connected to a single line. It is necessary to give a terminal address that identifies each terminal to messages flowing between each terminal and the host or terminal controller TC. That is, when the host or terminal controller TC receives a message from each terminal, it must identify which terminal the message was sent from, and vice versa. When a sent message is received, it is necessary to identify which terminal the message should be distributed to, and in both cases, the terminal address is required to identify them. be.

In the present invention, in order to add this terminal address to a message, the header portion of the message is expanded and the terminal address is included therein.

FIG. 2(A) shows a normal message format, and FIG. 2(B) shows an example of an expanded message format of the present invention.

A normal message format is formed of three parts: a protocol head, a message to the terminal, and a protocol tail, as shown in FIG.

The extended message format of the present invention is
As shown in Figure B, the protocol header section is expanded and a terminal address for identifying each terminal is inserted into this expanded header section. By doing this, it is possible to include addresses for more terminals (sub-terminals) than the initially limited number without changing the protocol.

Note that a message that is sent using this expanded message format is called a transmitted message, and a message that is received is called a received message.

One conceivable way to expand the message header is to change the application program of the host or terminal control device, but it is actually difficult to change the application program.

Therefore, as explained in the previous section, the present invention newly provides a process control table section 130 on the terminal 100 side.
and a line control layer section 140 are provided to expand the functions of the terminal side and expand the message header.

F ₂ (Operation of the present invention) The process of sending or receiving a message is performed by the terminal 1
The process begins when a certain terminal among 20 ₁ to 120n issues a process request to the line control layer section 140.

The line control layer unit 140 analyzes the contents of the process request issued from the terminal, and uses the process control table 130 to schedule the transmission or reception process requested by the terminal.

If the process being executed is a sending process, then
An extended message header containing the address of the terminal that issued the transmission request is added to the transmitted message, and the transmitted message is passed to the line control means 110.

If the process being executed is a receiving process, then
The receiving terminal is identified from the terminal address included in the extended message header of the received message, and the received message is distributed to that terminal.

In the manner described above, a number of terminals exceeding the number of addresses assigned to the terminals can be connected to a single line without changing the protocol.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 3 to 6.

FIG. 3 is a block diagram of the configuration of an embodiment of the present invention, FIG. 4 is an explanatory diagram of a process control table used in the embodiment, and FIG. 5 is an explanatory diagram of a process queue used in the embodiment. , FIG. 6 is a functional explanatory diagram of the line control layer section used in the same embodiment.

G ₁ (Description of configuration) In FIG. 3, a terminal device 100, a line control means 110, each terminal 120 ₁ to 120n, a process control table 130, a line control layer unit 140,
The single line 200 is as described in FIG.

In the line control means 110, a line control circuit 111 controls connection to the single line 200. Reference numeral 112 is an interface section, which internally includes a sending buffer, receiving buffer, and semaphore.
It has functions (none of which are shown) and interfaces with the line control layer section 140.

113 is a line control unit that controls the line control circuit 111 and the interface 113 according to the line control program.
control the behavior of

In each terminal 120 ₁ - 120n, 120 ₁ -
Reference numeral 120n denotes an application unit of each terminal, which program-controls each process such as transmission and reception executed by each terminal. 122 ₁ to 122n are interface parts, which internally have a transmission buffer, a reception buffer,
It has a semaphore function (none of which is shown) and interfaces with the line control layer section 140.

As described above, the line control means 110 and each terminal 120 ₁ -
The configurations of 120n and their internal parts are the same as those of the conventional ones, and their respective operations are also common.

Next, the process control table 130 will be explained with reference to FIGS. 4 and 5.

As shown in FIG. 4, the process control table 130 includes (i) a running process pointer, (ii) a first process pointer waiting to be executed, (iii) a last process pointer during execution, and (iv) a sending PCB for each terminal. (Process Control
block), (v) receiving PCB for each terminal, and (vi) terminal address for each terminal.

The contents of these (i) to (vi) will be explained with reference to the process queue shown in FIG. FIG. 5 shows an example of a process queue when the number of terminals is four.

(i) Running process pointer This pointer points to the PCB of the process being serviced by the line control program 113 at a certain point in time (see FIG. 5). Note that, as described above, the program of the line control unit 113, that is, the line control program, can service only one process at a time.
When the line control program is not servicing any process, this pointer is cleared to zero.

(ii) Pointer to the first process waiting to be executed Processes that cannot yet be serviced by the line control program are placed in a queue (process queue) on the PCB representing each process.
Configure. at the beginning of the process queue
This pointer points to the PCB (see Figure 5). When the process queue is null, ie, no process is attached to the process queue, this pointer is cleared to zero.

(iii) End process pointer waiting for execution Points to the PCB at the end of the process queue.
When the process queue is null, this pointer is cleared to zero.

(iv) Transmission PCB As shown in FIG. 4, the transmission PCB consists of a next execution waiting process pointer and process parameters.

The next execution waiting process pointer includes this
When a PCB is connected to a process queue, it indicates the next connected PCB after this PCB. When the PCB containing this is located at the end of the process queue, this pointer is cleared with an all mark (F in hexadecimal).

The process parameters include parameters necessary for transmission (transmission message length, etc.).

(v) Reception PCB The reception PCB includes a next execution waiting process pointer and process parameters. The function of the former is similar to the next execution process pointer of the transmitting PCB, and the latter includes parameters necessary for reception (receive message length, etc.).

(vi) Terminal address As shown in FIG. 4, the terminal address given to each terminal is stored in the terminal address.

The line control layer section 140 will be explained in detail in the following operation description.

G ₂ (Description of Operation) The operation of the embodiment shown in FIG. 3 will be explained with reference to FIGS. 4 to 6. The operations of the line control means 110 and each of the terminals 120 ₁ to 120n are the same as in the conventional system, so the explanation will focus on the line control layer section 140.

FIG. 6 shows each function performed by the line control layer unit 140 in relation to other parts.

The line control layer unit 140 has the following three main functions: (1) service to each terminal 120 ₁ to 120n, (2) process queue monitoring function, and (3) line control program monitoring function. ing.

The operation of the embodiment shown in FIG. 2 will be explained below, focusing on these three functions. Note that the numerals such as , etc. used in the description correspond to the same numerals shown in FIG. 6, and indicate the respective processing contents, operation contents, etc.

(1) Service to each terminal The process of sending or receiving is performed from terminal 120 ₁ to
120n issues a process request to the line control layer section 140.

The service functions for each terminal are shown in the order of operation.
It will look like this:

Accepts process requests from each terminal.

Analyzes the content of the process request and detects information such as whether it is a send request or a receive request, the requesting terminal, and the length of the message.

Organize the PCB of the requested process,
Enqueues to the process queue on the process control table 130 (see FIG. 5). Process requests generated at each terminal are enqueued to the process queue in the order in which they occur, so that process scheduling is performed in the order in which they occur.

(2) Process queue monitoring The line control layer unit 140 normally monitors the status of the process queue and the busy status of the line control program. If there is a process waiting in the process queue and the line control program is not busy, the following operation is performed.

PCB of the first process on the process queue
put into running state.

It extracts the necessary parameters from the PCB of the first process and requests the line control program to execute this process.

If the process request is a transmission request, add an extended message header to the transmission message by referring to the terminal address in the process control table 130,
This transmission message is passed to the line control program. The line control program, that is, the line control unit 113 transmits the transmission message received via the interface unit 112 from the line control circuit 111 to the single line 200.
A series of control operations transmitted to the controller are performed in the same manner as in the past.

(3) Line control program monitoring The line control layer section 140 normally monitors the completion status of the line control program. When the line control program completes one process, it performs the next operation.

(3-1) When the completed process is a sending process If the PCB being executed on the process queue is a sending PCB, perform the following processing.

Move the running PCB to the stopped state.

The end of transmission is notified to the terminal corresponding to the PCB.

If the PCB being executed on the process queue is not being sent, an error will occur.

(3-2) If the completed process of the line program is a receiving process request (A) The PCB being executed on the process queue receives
If it is a PCB, perform the following processing.

The received message is passed to the terminal corresponding to the PCB using the following method. That is, the extended message header is checked for consistency. If they match, the extended message header is deleted and the received message is passed to the terminal at the predetermined address.

If they do not match, process (B) or (C).

Bring a running PCB to a stopped state.

A reception notification is sent to the corresponding terminal.

(B) Matches the extended message header of the received message
If the PCB is in the waiting state, perform the following processing.

Delete the extended message header and pass the received message to the terminal corresponding to the PCB.

Delete the corresponding PCB from the process queue.

A reception notification is sent to the corresponding terminal.

(C) If there is no PCB on the process queue that matches the extended message header of the received message, perform the following processing for the terminal that matches the extended message header of the received message.

Delete the extended message header and pass the received message to the corresponding terminal.

Notify the corresponding terminal of forced reception. In the case of (C), when there is no reception request from the terminal side,
Since this is a case where a message is sent from the host side (not shown), forced reception is performed on the corresponding terminal.

Although one embodiment of the present invention has been described above, each structure of the present invention is not limited to the structure of the embodiment.

H [Effects of the Invention] As explained above, according to the present invention, the following effects can be obtained.

(b) Even if there is a limit to the number of addresses assigned to terminals, it is possible to connect more terminals than the number of addresses assigned to terminals to a single line by expanding the message header without changing the protocol. I can do it.

(b) Since an interface with a common configuration can be used between the line control program and each terminal application program, these interfaces can be unified.

[Brief explanation of the drawing]

FIG. 1: An explanatory diagram of the configuration of the present invention, FIG. 2: An explanatory diagram of an example of an expanded message format used in the present invention, FIG. 3: An explanatory diagram of an embodiment of the present invention, FIG. 4... FIG. 5 is an explanatory diagram of the process control table used in the embodiment. FIG. 6 is an explanatory diagram of the process queue used in the embodiment. FIG. 7
Figure: An explanatory diagram of a conventional method for connecting multiple terminals to a single line. 1 and 3, 100...terminal device, 110...line controller, 1201 _to 120n
...Terminal (including sub-terminal), 130... Process control table, 140... Line control layer section, 200
…single line.

Claims (1)

[Claims] 1. In a system in which a transmission slot of the terminal device 100 is assigned to each slot of a data frame of a specified length, and data is exchanged between the corresponding terminal device and a control device using the transmission slot, a predetermined transmission is performed. A plurality of terminals 12 are connected to the terminal device corresponding to the slot.
0 ₁ to 120n, and the terminal device 1
00 includes (a) a process control table 130 in which a schedule for processing process requests generated from the plurality of terminals 120 ₁ to 120n and information necessary therefor are set; and (b) a process control table 130 for each terminal using the process control table 130. ₁₂₀₁ to 120n, and sets it in the process control table 130. If the process to be executed is a sending process, an extended message header containing the address of the terminal that issued the sending request is created. If the process to be executed is a receiving process, a line control layer that performs processing to distribute the received message to terminals with addresses included in the extended message header of the sending slot. A method for connecting multiple terminals to a single line, comprising: a section 140.