JP2945200B2 - Data transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission system, and more particularly to an improvement in a polling transmission system.

[0002]

2. Description of the Related Art In a data transmission system including a control station and a plurality of subordinate stations connected to the control station in a multipoint manner, polling transmission is conventionally performed by the control station acting as a central control station of the transmission line. In general, all data transfer starts are performed from the control station, and commands are sequentially transmitted to the subordinate stations, and the corresponding subordinate station generally transmits data as a response only to the control station.

FIG. 4 is a block diagram for explaining an example of a conventional polling transmission system. In the conventional polling transmission system, a control station 1 regularly and sequentially controls subordinate stations 2, 3, and 4. , The presence or absence of a transmission request (FIG. 4)
(A)) For example, when the dependent station 2 wants to transmit data to the dependent station 4, the dependent station 2 transmits data to the control station 1 as a response to a command from the control station 1 (FIG. 4).
(B)) The control station 1 determines that the received data is data to the dependent station 4, and sends the data to the dependent station 4 as a command when the command transmission order to the dependent station 4 comes. The transmission procedure (FIG. 4 (c)) is performed. The delay in the data transmission between the dependent stations is large, and the transmission path is used twice for the same data transmission (FIG. 4 (b),
(C)), there is a problem that utilization efficiency is poor.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and uses polling transmission .
It is an object of the present invention to provide a transmission system that enables direct data transmission between dependent stations, reduces transmission delay, and reduces the load on a control station during data transmission.

[0005]

According to the present invention, in order to solve the above-mentioned problems, a data transmission end notification signal path is provided between a control station and a subordinate station, and the control station side is provided with a signal from a certain subordinate station to another substation. Means for detecting a response that the user wants to transmit data to the dependent station, and when receiving the response, wrapping means for connecting an upstream data transmission path from the dependent station to a downstream transmission path to the dependent station and returning the same, only setting means for sending a command to the effect that began folded to the driven genus station, and means for releasing the return of the transmission path by performing the interrupt processing upon receiving the transmission end notification signal from the dependent station, the subordinate station to, upon receiving a command notifying the start of the wrapping after sending a response to the effect that you want to perform data transmission to the slave station to the control station, and means for transmitting data relative to the dependent station is a destination desired, Den Po the transmission end notification if it completed the
The data transmission path using a-ring transmission system is characterized in that the means for sending digits set to the control station via the another of the data transmission end notice signal path.

[0006]

[Action] The folding means for folding the data between the uplink data transmission channel and the downlink data transmission path (switch means) provided in the control station side, when there is a request for data transmission at the same Judges between the dependent stations The return means transmits the data from the data transmission requesting station to the dependent station through the return means, and the dependent station which is the destination of the data receives the data. When the data transmission is completed, the dependent station on the data transmission request side uses the polling transmission method to send a data transmission end notification .
Data transmission end notification signal different from the data transmission path
The signal is sent to the control station via a path, the return means is released by interrupt control, and the process returns to the normal polling process.

[0007]

FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a control station serving as a central control station. Road 7
The substations 2, 3, and 4 are connected to the multipoint via. In the present invention, a data transmission end notification signal line 8 for notifying the end of data transmission is newly provided between the control station 1 and the dependent stations 2, 3, and 4. Switch 1 for connecting and folding data transmission path
1, a timer 12 and an interrupt control unit 13, and a synchronization signal for transmission is supplied by a timer 12 provided in the control station 1.

FIG. 2 is a sequence diagram showing an example of the present transmission system, and FIG. 3 is a diagram showing an operation flow in the control station 1. Hereinafter, embodiments will be described with reference to these drawings. The control station 1 sends a command addressed to the subordinate station 2 to be sent next via the downlink data transmission line 6 in accordance with normal polling processing (step 1).

The slave station 2 receiving the command from the downstream data transmission line 6 returns a normal response to the control station 1 via the upstream data transmission line 5 when there is no data to be transmitted to another slave station. If there is data to be transmitted to another dependent station 4, a “data transmission request to the dependent station” is returned to the control station 1 via the uplink data transmission line 5 as a response.

The control station 1 receiving this response determines whether this response is a "data transmission request to a dependent station" or "other" (step 2). If the request is a "data transmission request to a dependent station", the switch 11 is closed, the upstream data transmission path 5 is connected to the downstream transmission path 6, and the return of the data transmission path is started (step 3). afterwards,
A "data return start" command is sent to the subordinate station 2 (step 4), and processing other than polling is performed (step 5).

When the slave station 2 receives the “data loopback start”, it transmits data to the slave station 4 and, when the transmission is completed, sends a “data transmission end notification” to the control station 1 via the data transmission end notification path 8. Send out. When the control unit 1 receives the "data transmission end notification" by the interrupt control unit 13 (step 6), it opens the switch 11, releases the loopback of the data transmission path (step 7), and returns to the normal polling process. (Step 1).

[0012]

As described above, the present data transmission method enables direct data transmission between dependent stations in addition to ordinary polling processing, thereby increasing the speed of data transmission between dependent stations and using a transmission path. This has the effect of improving the efficiency. In addition, the end of data transmission between the dependent stations is notified on a separate line, and the control station does not need to perform any polling processing during data transmission between the dependent stations for processing the notification by interrupt control. The load will be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing an example of a sequence showing a procedure of a transmission system according to the present invention.

FIG. 3 is a flowchart in a control station.

FIG. 4 is a diagram illustrating an example of a conventional polling method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Control station, 2,3,4 ... Dependent station, 5 ... Up data transmission path, 6 ... Down data transmission path, 7 ... Synchronization signal path, 8 ...
Data transmission end notification signal path, 11: data transmission path return switch, 12: timer, 13: interrupt control unit.

Claims (1)

(57) [Claims] And 1. A control station consists of a multi-point connection to a plurality of dependent stations to the control station, the control station sends a command in a sequential time division to the plurality of slave stations, the command
In the data transmission method using the polling transmission method in which the dependent station sends a response in accordance with the following, data from the dependent station in the control station is returned to the dependent station .
It has a folding means, Po between the dependent stations and the control station
A data transmission end notification signal path for transmitting a data transmission end notification signal indicating that the subordinate station has ended data transmission to the control station separately from the data transmission path used for the ring transmission system, and further includes the notification in the control station. having an interrupt control means for processing the signal as an interrupt signal, if there dependent station there is data to be transmitted directly to another dependent station, and <br/> sends the request to the control station as the response, the The control station that has received the response causes the data from the dependent station to be folded back by the folding means, and sends a command to permit data transmission to the dependent station that has made the request. transmitting data, and sends the transmission completion notification signal if the transmission has been completed to the control station via the previous SL data transmission end notice signal path, the <br/> transmission end communication Control station receiving signal cancels the wrapping data, the data transmission method, characterized in that the return to operation of the normal polling transmission method.