JPS59154841A - Multiplex transmission control system - Google Patents

Abstract

PURPOSE:To improve the efficiency of a block multiplex communication control by preventing transmission insofar as permission of transmission is not given from a control station even if a transmission right frame is received in a loop transmission system where block multiplex and channel multiplex communication exist in mixture. CONSTITUTION:One control station and plural communication stations are connected in series in one loop communication line. When the control station 1 receives a transmission right frame from the preceding station in a block multiplex station, a frame requesting the permission of transmission is transmitted to the control station. When the transmission request frame is received, the control station gives the permission of transmission taking the data length included in the transmission request frame and the communication state of other block multiplex station into consideration. The communication station 1 transmits a data when the transmission permission frame is received. Further, the transmission right frame is transmitted to the next station after the end of data transmission.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Description of the field to which the invention pertains The present invention relates to a multiplex transmission control system, particularly to a multiplex transmission control system between a plurality of communication stations vertically connected in a loop-shaped communication path.

(2) Description of Prior Art Conventionally, various systems have been considered as communication systems that utilize loop-shaped communication channels. Broadly speaking, there are block multiplex communication methods that perform multiplexing in units of transmission blocks, and channel multiplex communication methods that perform multiplexing in small units such as bits or characters.

In block multiplex communication, only one station occupies the communication path at the time of transmission, so while it is possible to increase the communication speed to the line speed, it has the disadvantage that the hardware for buffer control increases.

In channel multiplex communication, communication slots for communication stations are always flowing on the communication path, so it can be used like a leased line. Also, since buffer control is not required, the hardware is not suitable for block multiplex communication. It requires less work, but it is difficult to send data all at once at high speed.

As mentioned above, block multiplex communication and channel multiplex communication have different characteristics. Therefore, it is appropriate to mix both methods on the same communication path and use them properly depending on the applicability. When data is transmitted from a plurality of communication stations to a communication channel, there are 8 methods to prevent the transmitted data from colliding with each other. As one of these methods, there is a transmission control method called a token method in the block multiplex communication method. In this method, a station that has finished transmitting data transmits a specific sequence to the next station, so that
The next station obtains the right to transmit, and only one station occupies the communication path at a time.In channel multiplex communication, the channel multiplex station synchronizes with some kind of synchronization signal, and transmits data at regular intervals. It is configured to send and receive data. As mentioned above, in the channel multiplex communication method, data transmission is completely synchronous, whereas in the block multi-N communication, it is asynchronous. Therefore, it is difficult to mix the block multiplex communication method and the channel multiplex communication method on the same communication channel. In this case, a transmission control method is required to avoid transmission collisions between the different transmission formats described above. (3) Purpose of the invention This is intended to provide a transmission control method when communications are mixed at the same time. In the present invention, (1) a loop-shaped communication channel and a vertically connected communication channel are provided. ! In a communication system consisting of j number of communication stations and control stations, only the communication station that detects reception of a transmission right frame consisting of a specific sequence has the right to transmit data, and each communication station has the right to transmit data. When the control station detects reception of a frame, it becomes possible to send a transmission request frame to the control station to request permission for transmission. (II) When the control station detects reception of this transmission request frame, it sends a transmission request from its own station. By checking the status and deciding when to send the transmission permission frame, the control station monitors and controls the transmission of the block multiplexing station to prevent collision with the transmission of the channel multiplexing station, and (iii) the communication station When transmitting a transmission request frame, information indicating the length of the data to be transmitted next is inserted into the transmission request frame, the control station receives this transmission request frame, detects the data length information, and the communication station Compare the time when transmission ends when transmitting this data and the time when your own station should transmit data,
By determining whether to transmit the transmission permission frame immediately or with a delay based on the comparison result, it becomes possible to efficiently control the transmission of the block multiplex communication station.

(4) Explanation of the structure and operation of the invention Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows the overall configuration of a communication system to which the present invention is applied, and FIG. 2 shows an example of a transmission control sequence. Fig. 3 is an embodiment of a block diagram of a communication station, Fig. 4 is an embodiment of a block diagram of a control station, Fig. 5 is another embodiment of a block diagram of a communication station, and Fig. 6 is a control station block diagram. Another block diagram of
An example is shown.

A control station and a plurality of communication stations are vertically connected in a loop communication path as shown in Figure 1, and when communicating between the communication stations, reception of a transmission right frame is required as shown in Figure 2. For example, the communication station 1 that has detected this transmits a transmission request frame to the control station to request transmission permission 0T. In response to this, the control station determines the transmission timing of the transmission permission frame and issues the transmission permission frame. After receiving the transmission permission frame, the communication station IVi sends the data to another communication station, and then passes the transmission right frame to the next communication station 2.

The operation of the communication station will be explained below with reference to FIG. 3. [In the block diagram of FIG. 3, 301 is a control frame reception detection circuit;
02 is a control frame transmitting circuit, 303 is a data transmitting circuit, 304 is a data receiving circuit, 306 Fi gate circuit, 3
07 is transmit data multiplexer, 308.309Vi
(l-flzof+, L/ shiha.

It's a driver.

The serial signal of the loop-shaped communication path inputted from the signal line 3α is shaped by the receiver 308 and outputted to the signal flllj, 31). One of the signal lines 3b is connected to the data receiving circuit 3.
04, and the other one passes through a gate circuit 306 and a transmission data multiplexer 307, and is output to a loop-shaped communication path by a driver 309.

The remaining one of 36 is input to the control frame reception detection circuit 301. The data receiving circuit 304 constantly monitors received data, and when it detects data addressed to its own station, the data receiving circuit 304 receives the data and passes it to another control unit (not shown). A control frame reception detection circuit 301 receives and detects a transmission right frame and a transmission permission frame. The signal line 3C output from the data transmitting circuit 303 is a transmission request signal, indicating that the data transmitting circuit 303 requests data transmission. When the control 7L/-me reception detection circuit 301 detects the start of reception of a transmission right frame and the transmission request signal on the signal line 3C is on, the signal line 3d is first turned on. As a result, the gate 306 prohibits transmission of the transmission right frame to the downstream. Furthermore, the control frame reception detection circuit 30
When the transmission right frame being received in step 1 is correctly received,
The circuit 301 turns off the signal line 3d, instructs the control frame transmission circuit 302 to transmit a transmission request frame through the signal line 3e, and turns on the internal transmission right memory. When the control frame reception detection circuit 301 detects that the reception sequence of the transmission right frame becomes abnormal in the middle, it turns off the signal line 3d and returns to the initial state.

The control frame transmitting circuit 302, which has been instructed by the circuit 301 to transmit the transmission request frame through the signal line 3e, outputs the signal line 3f and instructs the transmit data multiplexer 307 to output the signal on the signal line 3g. As described above, the transmission request frame outputted from the control frame transmission circuit 302 to the signal line 3g passes through the transmission data multi-IV chainer 307, and is outputted from the driver 309 to the loop-shaped communication path. After sending out the transmission request frame, the control frame transmission circuit 302 turns off the signal line 3f and returns the transmission data multiplexer 307 to its normal state. The transmission data multiplexer 307 relays the signal on the signal line 3h when it is energized.

When the control frame reception detection circuit 301 detects the start of reception of a transmission permission frame, it refers to the transmission right memory inside the circuit 301, and if this memory is on, the circuit 301 turns on the signal line 3d'ii. Prohibits transmission of frames allowed to be sent to subsequent locations. Furthermore, when the control frame reception detection circuit 301 correctly receives the transmission frame, the circuit 301 turns off the signal line 3d and instructs the data transmission circuit 303 to start transmitting data via the signal line 3AK. As a result, the data transmission circuit 303
turns on the signal 3t and transmits data multiplexer 3
07 to output the signal of signal line 3m.

As described above, the data outputted from the data transmission circuit 303 to the signal line 3m passes through the multiplexer 307, and is outputted from the driver 309 to the loop-shaped communication path. When the data transmission circuit 303 finishes transmitting data, the signal line 3t
is turned off, and the transmission data multiplexer 307 is returned to its normal state. Also, the signal line 3 is connected to the data transmission circuit 303.
The control frame reception detection circuit 301 is notified of the end of data transmission by the control frame reception detection circuit 301.

In response to this data transmission end notification, the control frame reception detection circuit 301 turns off the internal transmission right memory and instructs the control frame transmission circuit 302 to send out the transmission right frame through the signal line 3p.

The control frame transmission circuit 302 turns on the signal line 3f,
The multiplexer 307 is instructed to output the signal on the signal line 3g.

As described above, from the control frame transmission circuit 302 to the signal line 3g
The transmission right frame output to the multiplexer 307
After transmitting the transmission right frame, the C control frame transmission circuit 302, which passes through the driver 309 and outputs it to the loop communication path, turns off the signal line 3f and returns the transmission data multiplexer 307 to its normal state.

Further, the operation of the control station will be explained with reference to FIG.

In the block diagram of FIG. 4, 401 is a control frame reception detection circuit, 402 is a control frame transmission circuit, 403 is a channel multiplex frame storage/transmission circuit, 404 is a timer circuit,
405 is a comparison circuit, 407 is a gate circuit, 408 is a transmission data multiplexer, 409U receiver, and 410 is a driver.

The signal on the loop communication path inputted from the signal line 4a is shaped by resin nodes 409 and outputted to the signal line 4h.

One of the signal lines 4b is input to the channel multiplex frame storage/transmission circuit 403, and the other one is input to the gate circuit W6407.
, passes through the transmit data multiplexer 408 and is output to the loop-shaped communication path by the driver 410. Signal line 4b
The remaining one is input to the control frame reception detection circuit 401. The channel multiplex frame storage/transmission circuit 403 receives the channel multiplex N frame from the input from the signal line 4b, stores the channel multiplex frame data in the buffer, and, by the trigger of the output signal 4C of the timer 404, stores the channel multiplex frame data in the buffer. It has a function to send multiple frame data to a loop-shaped communication channel. Control frame reception detection circuit 4
01 monitors whether a transmission request frame or a transmission right frame is received from the input of the signal line 4b. When the control frame reception detection circuit 401 detects the start of reception of the transmission request frame, it turns on the signal line 4d and prohibits the transmission request frame from being transmitted to the subsequent stage using the date circuit 407. When the transmission request frame is correctly received, the circuit 401 refers to the signal line 4e, and if it is off, instructs the control frame transmission circuit 402 on the signal line 4f to transmit the transmission permission frame. If the signal line 4e is on, the circuit 401 turns on the internal transmission hold memo IJ'.

When the transmission hold memory in the circuit 401 is on,
From the channel multiplex frame storage/transmission circuit 403, a signal line 4. ! When the channel multiplexed frame transmission light -11 = completion deposit signal is output to 7, the transmission permission hold memory is turned off, and a transmission permission frame transmission instruction signal is sent from the control frame reception detection circuit 401 to the signal line 4f. The output 0 signal line 4e is the 0 output from the comparison circuit 405.The comparison circuit 405 is the count value signal line 4 of the timer 404.
The signal line 4e is turned off a certain period of time before the channel multiplex frame is to be transmitted, and the signal line 4e is turned off from then on until the end of the channel multiplex frame transmission.
'fr is on. This fixed period of time is set to give sufficient time for the communication station to finish transmitting the data. When the 0 control frame transmitting circuit 402 is instructed to transmit a transmission frame via the signal line 4f, the control frame transmitting circuit 402 4h is turned on and instructs the transmission data multiplexer 408 to output a signal to the signal line 4.

As described above, from the control frame transmission circuit 402 to the signal line 4
The transmission frame to be output to the multiplexer 40
8 and is output to the loop-shaped communication path by the driver 410. At the time w6402, transmission = 12- When the transmission of the permission frame is completed, the signal line 4 is turned off and the transmission data multiplexer 408 is returned to the normal state. The multiplexer 408 normally connects the signal line 4
It relays the signal of t. Control frame reception detection circuit 4
01 starts receiving the transmission right frame, signal line 4
d is turned on, and the date circuit 407 prohibits the transmission right frame from being transmitted to the downstream. When the transmission right frame is correctly received, the control frame reception detection circuit 401 refers to the signal line 4m, and if it is off, instructs the control frame transmission circuit 402 to transmit the transmission right frame through the signal line 4rL. If the signal line 4m is on, the transmission right reservation memory inside the control frame reception detection circuit 401it is turned on. When the transmission right reservation memory in the circuit 401 is on, when the channel multiplex frame storage/transmission circuit 403 outputs a signal indicating completion of channel multiplex frame transmission to the signal line 41, the transmission right memory is turned off and the above-mentioned A signal instructing transmission right frame transmission is output from the circuit 401 to the signal line 4.

Signal 13477+ is output from comparison circuit 405.

The circuit 405 constantly monitors the count value signal line 4r of the timer 404, turns off the signal line 4m a certain period of time before transmitting the channel multiplex frame, and turns off the signal line 4m from then until the end of channel multiplex frame transmission. 4m is on. This certain period of time is set to provide sufficient time for the communication station to finish transmitting the transmission permission frame after receiving the transmission permission frame. A signal line 4 is connected to the control frame transmission circuit 402. When a transmission right frame transmission instruction is issued from y+ and VC, the signal line 4h is turned on and the transmission data multiplexer 408 is instructed to output a signal on signal &14.

As described above, the control frame transmitting circuit 402 and the signal line 4
The transmitted frame output to is multiplexed v408
The signal is output to a loop-shaped communication path by the driver 410. When the circuit 402 completes sending out the transmission right frame, it turns off the signal line 4h and sends the transmission data multiplexer 408'5jl! 1 Return to normal state. The channel multiplex frame storage/transmission circuit 403 receives the channel multiplex frame inputted from the signal line 4b according to job and transmits the channel multiplex frame to the circuit 40.
Accumulate in a buffer within 3. Further, when a transmission instruction is issued from the timer 404 through the signal line 4C, the signal M4P'
fr is turned on, instructing the transmission data multiplexer 408 to output the signal on the signal line 4q. In this state, the channel multiplexed frame read from the buffer in the circuit 403 and output from the circuit 403 to the signal line 4q passes through the multiplexer 408 and is sent to the driver 41.
0, it is output to the loop communication path.

Another embodiment of the present invention is shown in FIGS. 5 and 6 f! /u'i is shown.

FIG. 5 shows an embodiment of the communication station, and FIG. 6 shows an embodiment of the control station. The circuit operation is shown in Figure 5 and Figure 3, and Figure 6 and Figure 4.
It corresponds to the figure and performs almost the same operation. That is, circuits 501 to 509 correspond to circuits 301 to 309, respectively, signal lines 5α to 5P correspond to signal lines 3α to 3P, respectively, and circuits 601 to 610 respectively correspond to circuit 4.
01 to 410, and signal lines 6α to 6r correspond to signal lines 15- 4α to 4r, respectively. The difference between the two is that a signal 5x is added to FIG. 5, and a signal 6x is added to FIG. 6.

This difference will be described below. In FIG. 5, a signal line 5x indicates the length of data to be transmitted next by the data transmitting circuit 503. Control frame transmission circuit 501;
I, receiving the signal line 5x, adds the above transmission data length information to the transmission request frame and transmits it. In FIG. 6, a signal line 6x indicates the transmission data length information of the transmission request frame received by the control frame reception detection circuit 601. This signal m6x is compared with the timer value signal line 6r of the timer 604 by a comparison circuit 605, and if the former is smaller than the latter by a certain value or more, the signal line 6tf is turned off, otherwise the signal 11ji16e is turned on, and the channel multiplex frame is It remains on until the end of transmission.

The above procedure is carried out in detail using the judgment criteria used when the control station transmits the transmission permission frame, that is, the transmission data length notified by the communication station to provide sufficient time for the communication station to finish transmitting the data. It can be considered that this is to reduce the waiting time for data transmission by the communication station.

(5) Description of effects As explained above, according to the present invention, in a communication system configured of a plurality of communication stations and a control station vertically connected in a loop-shaped communication path, a transmission right frame consisting of a specific sequence can be used. In a communication system in which only a communication station that has detected reception of a transmission right frame has the right to transmit data, means for enabling each communication station to transmit a transmission request frame to a control station by detecting reception of a transmission right frame. and a means for starting data transmission when a transmission permission frame is received after sending a transmission request frame, a means for detecting reception of a transmission request to the control station, and a means for transmitting permission after an arbitrary time by detecting the frame. By providing means for transmitting frames, it is possible to accommodate communication stations having synchronous transmission triggers, which are different from the communication stations having asynchronous transmission triggers subject to the above control, on the same communication channel. There is. Furthermore, the communication station is provided with a means for inserting data length information into the transmission request frame, and the control station is provided with a means for inserting data length information into the transmission request frame. By providing a means to compare the frame to when it should be sent and thereby decide when to send the permission frame to send,
It is possible to reduce the communication station's data transmission latency.

[Brief explanation of the drawing]

FIG. 1 shows the overall configuration of a communication system to which the present invention is applied, FIG. 2 shows a transmission control sequence of the present invention, and FIGS. 3 and 5 each show an embodiment of a communication station according to the present invention. Fourth
6 and 6 respectively show embodiments of the control station according to the present invention. 301.501...Communication station control frame reception detection circuit, 302.502...Communication station control frame transmission circuit, 303,503...Communication station data transmission circuit,
304,504...Communication station data receiving circuit, 30
6.407,506,607...gate circuit, 307
．． 507...Communication station transmission data multiplexer,
308,409,508.609...receiver,
309,410,509,610...driver,
401,601...Control station control 7 frame reception detection circuit, 402,602...Control station control frame transmission circuit, 403,603...Channel multiplex frame accumulation/transmission circuit, 404.604...Timer, 4
05.605... Comparison circuit, 408°608...
・Control station transmission data multiplexer. Patent applicant Hiroshi Mori, patent attorney representing Nippon Telegraph and Telephone Public Corporation

Claims (1)

[Claims] (1) In a communication system consisting of a loop-shaped communication path and a plurality of communication stations and control stations vertically connected to this communication path, only the communication station that detects reception of a transmission right frame consisting of a specific sequence transmits data. In a communication system in which each communication station has the right to transmit, each communication station has means for enabling transmission of a transmission request frame to a control station by detecting reception of the transmission right frame, and the control station The communication station has means for detecting reception of a request frame, and means for transmitting a transmission permission frame after an arbitrary time by detecting reception of the transmission request frame, and the communication station transmitting the transmission request frame receives the transmission permission frame. A multiplex transmission control method that makes it possible to start data transmission by detecting frame reception. (O) The communication station has means for inserting information on the length of data to be transmitted next into the transmission request frame, and the control station is configured to insert information on the length of data to be transmitted next into the transmission request frame, Means for comparing data length information on the frame with the time at which the communication station that transmitted the transmission request frame is expected to finish data transmission, and means for determining the transmission timing of the transmission frame based on the comparison result. A multiplex transmission control method 0 according to claim (1), characterized in that