JPH0554295B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a loop transmission system in which a plurality of remote stations are cascaded in a loop via a common data transmission path and data is transferred between any two remote stations.

A conventional device of this type is shown in FIG. In the figure, 1 is a centralized exchange, 2, 3, 4...
n is a remote station, and 100 is a loop transmission line.

FIG. 2 is a format diagram showing an example of the configuration of a signal frame that is circulated and transmitted on the loop transmission line 100. In FIG.
... are communication slots, and the numbers within the frames are slot numbers. In the conventional system, each remote station is assigned one communication slot, for example, remote stations 2 and 3 are assigned slots 2 and 3, respectively.

FIG. 3 is an explanatory diagram showing a connection operation between remote stations, and shows a case where remote station 2 requests connection to remote station 3. In FIG. 3, the same symbols as in FIG. 1 indicate the same parts, and 101, 102, and 103 represent the respective signals transmitted by the loop transmission line 100.

That is, when remote station 2 attempts to connect to remote station 3, it sends out through slot 2 a connection request containing an address signal indicating the destination remote station 3. This is signal 101. When the signal 101 enters the central exchange 1 and is decoded, the central exchange 1 uses the slot 3 to send out a connection instruction signal. This is signal 102. Signal 102 enters remote station 3 and
checks whether connection is possible, and if connection is possible, selects slot 3.
Sends a connection possible signal using . This is signal 10
3, when the signal 103 enters the central exchange 1, the central exchange knows that the connection control is completed at this point, and thereafter performs the exchange as shown in FIG. In FIG. 4, the same symbols as in FIG. 3 indicate the same parts, and 104, 105, 106, and 107 represent the respective signals transmitted by the loop transmission line 100. That is, although the signal 104 sent from remote station 2 is input to slot 2,
A signal 106 that is input into slot 3 at the central exchange 1 and enters the remote station 3 as a signal 105 and sent out from the remote station 3 is input into slot 3 but is input into slot 2 at the central exchange 1. , and enters the remote station 2 as a signal 107.

In the conventional method, one slot is assigned to each remote station as described above, so if you try to communicate between two remote stations,
Two slots are always required, and the number of communication slots equal to the number of remote stations is required, resulting in a disadvantage that the slot utilization rate is poor.

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional system, and improves slot utilization efficiency by providing an exchange control slot that is commonly used by each remote station in the transmission frame. The purpose is to provide a method that can be used.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 is a block diagram showing an embodiment of the present invention. In FIG. 5, the same reference numerals as in FIG. 1 indicate the same or corresponding parts, and 10 is a synchronization station. However, remote stations 2, 3, and
4, . . . n differ from 2, 3, 4, .

Figure 10 shows an example of the configuration of a synchronization station.
11 is the slot access receiver, 12 is the slot access transmitter, and 13 is the entire synchronization station.
14 is a synchronization delay correction buffer section, 15 is a transmission slot/frame generation counter, and 16 is a scanning address generation section compatible with the remote station.

FIG. 6 is a format diagram showing the structure of a frame used for data transmission according to the present invention. 6th
In the figure, the same symbols as in Figure 2 indicate corresponding parts,
1100 is an exchange control slot (hereinafter abbreviated as EXC); EXC 1100 is a scanning address (hereinafter abbreviated as scanning address or SA) 1101 compatible with the remote station, destination address DA 1102, communication slot number SL 1103 to be used, and flag F ₁ , F ₂ , F ₃ , F ₄ and check code CH1104 (check codes include parity check code for SA, DA, F ₁ , F ₂ , F ₃ , F ₄ , transfer check code/reverse transfer check code, (CRC check code etc. can be used), and the communication slot is composed of a flag _F5 and communication data DATA1105. In addition, flag F ₁ is a connection request, F ₂ is a connection ready state, F ₃ is an indication that communication is in progress (set by the calling side), F ₄ is also an indication that communication is in progress (set by the called party), and F ₅ is an indication of use. It is. Further, the total number m of communication slots can be set such that n>m for the total number n of remote stations.

By the way, as shown in FIG. 6, the EXC 1100 represents only the connection control information of the remote station for one scanning address SA, so in order to represent the connection control information for the remote stations of n stations, the scanning It is necessary to sequentially change the address SA 1101 and scan the connection control information of the remote station. The scanning address is changed cyclically at the synchronization station 10, and an example of the occurrence of this cyclical scanning address is shown in FIG. In FIG. 11, one value of SA is used as a lead frame in the first round of the transmission loop and as a write frame in the second round. The read frame has the function of reading connection control information of a remote station (sometimes referred to as a station) into the EXC slot, and the write frame has the function of writing the contents of the EXC slot to each station. SAs sent over two frames are usually from 1 to n.
It is configured to make one round in 2n frames. (If the transmission loop rotation time is adjusted to be one frame long for the total transmission delay time including the delay correction time at the synchronization station, one round of SA will be 2n frames, but if multiple frames are long is SA
One round is multiple times 2n frames).

Figure 7 is a diagram showing the contents of the connection control memory that holds the connection information of the remote station, and the address for accessing this memory is EXC11.
The address is the same value as SA1101 in 00, and the word stored at that address is as shown in Figure 6.
DA, SL, F ₁ , F ₂ , F ₃ , and F ₄ in EXC1100 are included.

Further, as a supplementary explanatory diagram of FIG. 7, FIG. 12 shows the structure of the connection control memory and the relationship between the memory address and the scanning address SA. In FIG. 12, the connection control memory is connected to the exchange control slot.
The scanning address SA in EXC is made to match the memory address and remote station number. That is, for example, SA=
2, the connection control information corresponding to remote station 2 is held at the memory address=2 location. Therefore, such a structure means that by providing all remote stations with connection control memory, all remote stations can have connection control information for all remote stations.

FIG. 8 is a block diagram showing an example of the configuration of each remote station, where 100 is a transmission path similar to 100 in FIG. 23 is a receiving section. The signal input from the transmission unit 100 to the remote station (after being demodulated if necessary) is input from the serial signal input terminal of the shift register provided in the slot access unit 20, is sequentially shifted, and is output from the serial signal output terminal. It is shifted out (via a modulator if necessary) and sent out again onto the transmission path. By detecting SYN1000, the slot access unit 20 can know which part of the format shown in FIG. 6 is present in which part of the shift register of the slot access part 20, and 21, the data to be sent to the transmission line 100 can be input to the parallel input terminal of the shift register, and the receiving section 23 can load desired data from the parallel output terminal of the shift register into the register in the receiving section 23. I can do it. The connection control section 22 controls data input/output of the EXC 1100 shown in FIG.

FIG. 9 is a block diagram showing an example of the configuration of the connection control section 22, in which the same reference numerals as in FIG. 8 indicate the same parts, and 2
4 is a connection control memory, 25 is a connection control controller, 21 is a transmitter, and 23 is a receiver. (still,
In FIG. 9, there is no line directly connecting the slot access section 20, the transmitting section 21, and the receiving section 23, but the transmitting section 21 has a bus 227, gates 221, 222,
In the receiving section 23, the signals are connected via a route via gates 220, 223, and a bus 227, which is equivalent to that shown in FIG. )220,
221, 222, and 223 are gates, and the timing at which these gates are opened is determined respectively.
Although it is determined based on the detection time of SYN1000, the control signal line is not shown in FIG. 224 and 225 are address lines, 22
7 is a data line.

Here, the connection control controller 25 receives address signals from the slot access section 20 via the address line 224, and outputs these synchronized address signals to the address line 225, so that the connection control controller 25 receives the address signals in synchronization with the slot access section 20. The transmitter 23 and the transmitter 21 are configured to be controlled.

FIG. 13 is a diagram explaining the principle of realizing distributed exchange by remote stations.

In the figure, after a connection request from remote station 2 is written to address 2 of its own connection control memory 24, when the EXC slot of the lead frame reaches address 2 scan, the connection control memory 2
The connection request at the address 2 of the remote station 3 is read into the EXC slot, and is written to the address 2 of the connection control memory of the remote station 3 in the write frame after one round. (Similarly, this write frame is written to address 2 in the connection control memory in other stations as well.) As a result, remote station 3
It learns that there are connection requests from stations, and if it is addressed to three stations, it determines the internal state, and if the connection is possible, it can write that information to address 2 of the connection control memory 34. This connectability information is read into the EXC slot when the EXC slot of the lead frame reaches address 2 scan again, and is written into the connection control memory of all stations including the two stations at the time of the following write frame. By reading this, the second station knows that the third station is in a connectable state, and can proceed to the next connection control operation. According to this principle, remote stations can perform decentralized switching by themselves without the need for a centralized switching center.

FIG. 14 is a diagram illustrating a two-port connection control memory of a remote station. In the figure, the connection control memory 24 has address lines 224, 2
25 and gates 220, 223, 221, and 222, it is a two-port memory that can be accessed from both the slot access section 20 side and the connection control controller 25 side. In particular, 2-port memory 2
4, the slot access section 20
If there is a conflict between accesses from the slot access section and the connection control controller 25 side, the slot access section side is prioritized and the connection control controller side is made to wait.

That is, the slot access unit 20 accesses the connection control memory 24 at regular intervals, and the connection controller 25 accesses the connection control memory 24 at any timing.
Access 4. Therefore, the connection control memory 24
is a certain period of time before and after the access timing of the slot access section 20.
Access is prohibited during the period of 5 days.

FIG. 15 is a diagram illustrating the operation of a calling side connection request.

FIG. 16 is a diagram illustrating the operation of receiving a connection request on the called side.

FIG. 17 is a diagram illustrating the operation of calling side connection confirmation.

FIG. 18 is a diagram illustrating the operation of the called side connection confirmation/communication start.

FIG. 19 is a diagram illustrating the operation of the calling party during communication initiation and communication.

FIG. 20 is a diagram illustrating the operation during communication on the called side.

Next, the operation of the apparatus shown in FIG. 5 will be described in the case where data is transferred from remote station 2 to remote station 3. First, the fifth
The calling side connection request will be explained with reference to FIG. 9, FIG. 15, and FIG. The remote station 2 uses the receiving unit 23 and the connection controller 25 to determine which communication slot has the use display flag _F5 not set.
_F5 flag reception and connection control controller 2
The determination is made by determining and detecting an unused communication slot when a connection request occurs in step 5.

Here, if we know that the communication slot 4 has no flag _F5 set and is an empty slot, we reserve the communication slot 4 (reservation is done using the _F5 flag) and then write the address of the connection control memory 24. 2 (the same address position as address SA1101 of remote station 2), the destination address DA is 3 as the calling side connection request data.
Set the communication slot number to 4, and set the connection request flag.
Setting F ₁ to logic "1" (see FIGS. 7 and 12), designating address 2 through the address line 225, and applying the data through the gate 221, performs writing. As explained earlier, the synchronization station 10 transmits the value of SA1101 (scanning address) in EXC1100 while changing it sequentially for each frame.
Only the remote station whose own station address is specified by SA 1101 or DA 1102 of 00 will have the right to use the EXC 1100. When the value of SA1101 becomes 2, this address is given to the connection control memory 24 from the address line 224 in the remote station 2, the data at this address position (see FIG. 7) is read out, and the gate 222 and slot access section 20 The signal is sent out to the transmission line 100 via.

The EXC 1100 data sent from the remote station 2 to the transmission line 100 is transmitted to the connection control memory 3 of the other remote stations 3, 4,...n.
Gate 3 to address 2 position of 4, 44,...n4
20, 420, . . . n20. Next, reception of a connection request on the called side will be explained using FIG. 16. At each remote station,
The contents of the connection control memory 24 of its own station are sequentially read out and processed, but the remote station 3 reads the data at address 2 (contents shown in FIG. 7) of the connection control memory 24 of its own station, and It learns that it has received a connection request from remote station 2 using communication slot 4 by determining that _F1 is on and DA = own station, and if the connection is possible by comparing it with the connection status of the terminal. For example, connectable status flag F ₂
Set to logic "1". The data stored at address 2 in the connection control memory 24 of the remote station 3 is read out again to the transmission line 100 using a lead frame and sent to the synchronization station 10.
Return to In FIG. 10, the synchronization station 10 has an EXC 1100 and multiple communication slots 1.
001, 1002, ... and temporarily stored in the synchronization delay correction buffer 14, and this temporarily stored EXC 1100 is used when the scanning address generation unit 16 makes the second round in the same SA when sending the next frame. In other words, when SA=2 in this case and it is the second round, change the SA=2 read of EXC1100 to SA=2 write, and reconfigure and send the frame while leaving the other contents of EXC1100 unchanged. . (At this time, multiple communication slots 10
01, 1002, . . . are not changed and are reconfigured into the corresponding frames as they are. ) In this way, the operation enters the next stage of calling side connection confirmation shown in FIG. In Figure 17, SA1101 indicates a light frame of 2, so EXC1100
is again written to address 2 in the connection control memory 24 of the remote station 2. The calling remote station 2 uses its own connection control memory 2
When the connection control controller 25 reads the data at address 2 of 4 and finds that the connection enabled state flag F ₂ is set, it sets F ₃ in the connection control memory 24 during communication on the calling side. This calling side communication data is read out using a read frame with SA=2, and then transmitted to the other station using a write frame with SA=2. After setting the calling side communication flag, the connection controller 25 makes the reserved communication slot exclusive and sets the _F5 flag again. However, since the communication slot 4 is already reserved and the flag _F5 is set, the flag _F5 remains set even if it is not set again.

This operation causes the called side to proceed to the called side connection confirmation/communication start stage shown in FIG. In FIG. 18, if the connection controller 35 is addressed to its own station and F ₁ , F ₂ , and F ₃ are all on, it sets a called side communication flag F ₄ in the connection control memory 34 . The called side communication data set in the connection control memory 34 is read out using the read frame with SA=2, as described above, and then transmitted to the other station using the write frame with SA=2. The connection controller 35 then monopolizes the designated communication slot, puts it into a communication start state, and starts the transmitting section 31 and the receiving section 33.

On the other hand, the calling side proceeds to the calling side communication start/communication stage shown in FIG. The calling side connection controller 25 reads the connection control memory 24, learns that the called _F4 flag is turned on while the calling _F3 flag is on, and sets the communication start state. As a result, the transmitting section 21 and receiving section 23 on the calling side are activated, and communication can begin.

As described above, the connection operation between the remote stations 2 and 3 is completed and communication can begin, but the operation on the called side is as shown in FIG. 20. That is, in the remote station 3 on the called side, after activation, the receiving section 33 and the transmitting section 31 receive the communication data of the communication slot being secured (communication slot 4 in this example), and the response data etc. using the same slot, the busy flag F ₅ =
1 can be sent with.

The end of communication can be determined by resetting the communication display flags F ₃ and F ₄ .

As described above, according to the present invention, by providing one common exchange control slot and a plurality of communication slots that can be commonly used by multiple remote stations in a transmission frame, a loop transmission system exchange with excellent slot usage efficiency can be realized. The device can be realized. In addition, each remote station has a connection control memory, which is cyclically written to and read by the exchange control slot EXC of the transmission frame, and written to and read from the connection control controller within the remote station. It is possible to realize decentralized exchange.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a conventional device, FIG. 2 is a format diagram showing an example of the structure of a conventional signal frame, FIGS. 3 and 4 are explanatory diagrams explaining the operation of the device in FIG. FIG. 5 is a block diagram showing an embodiment of the invention, FIG. 6 is a format diagram showing an example of the structure of a signal frame of the invention, FIG. 7 is a diagram showing the contents of the connection control memory of the invention, and FIG. is a block diagram showing an example of the configuration of each remote station in FIG. 5, FIG. 9 is a block diagram showing an example of the configuration of the connection control section in FIG. 8, FIG. 10 is a diagram of an example of the configuration of the synchronization station, and FIG. is an explanatory diagram of the scanning address in the transmission frame, Fig. 12 is an explanatory diagram of the structure of the connection control memory and its relationship with the memory address, Fig. 13 is an illustration of the principle of realizing distributed exchange by remote stations, and Fig. 14 is a diagram of the remote station. Explanatory diagram of the station's 2-port connection control memory, Part 1
Figure 5 is an explanatory diagram of the operation of the calling side connection request, Figure 16 is an explanatory diagram of the operation of accepting the called side connection request, Figure 17 is an explanatory diagram of the operation of the calling side connection confirmation, and Figure 18 is the operation explanation of the called side connection. FIG. 19 is an explanatory diagram of the operation during confirmation/communication start, FIG. 19 is an explanatory diagram of the operation during the calling party's communication start/during communication, and FIG. 20 is an explanatory diagram of the operation during called communication. 2, 3, 4, n...each remote station,
10...Synchronization station, 100...Transmission line,
20...Slot access unit, 22...Connection control unit, 24...Connection control memory, 1000...Synchronization slot, 1100...Exchange control slot, 10
01, 1002...Each communication slot, 1101...
...scanning address. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. In a switching device for a loop transmission system for communicating between arbitrary remote stations in a loop transmission system in which a plurality of remote stations are connected in a loop through a common transmission path, , a connection control memory for storing connection control information for the entire transmission system is provided, and this connection control memory has a means for writing and reading access both from the transmission line side and from inside the remote station, A synchronization slot that transmits synchronization signals to a synchronization station connected to The exchange control slot has an address corresponding to the number of the remote station, and by sequentially and cyclically changing the address, the address of the control information memory corresponding to the number of all the remote stations in the loop transmission system is set. Each remote station has a means for scanning the in-use flag of each communication slot and determining the number of an unused communication slot, and when receiving an exchange control slot from the transmission line, the above-mentioned connection control Means for writing the contents of the exchange control slot in the memory at the location specified by the scanning address, and reading the contents of the connection control memory at the position specified by the scanning address of the exchange control slot into the exchange control slot. The data written or updated to the connection control memory of one remote station from inside the remote station is read out from the connection control memory contents to the exchange control slot by the means for reading out the contents of the connection control memory to the exchange control slot in the transmission frame. The exchange control slot in the transmission frame is written to the connection control memory of all remote stations by the writing means from the exchange control slot to the connection control memory by circulating the loop transmission line. Alternatively, the calling remote station, where the transmission request exists, stores the flag indicating the connection request, the communication destination address, Write the communication slot number of an unused communication slot, and when the scanning address of the exchange control slot indicates the address of your own station number, read the contents of the connection control memory at the location specified by the above scanning address into the exchange control slot. By writing to the connection control memory of all remote stations using the writing means from the exchange control slot to the connection control memory, the contents of the connection control memory of the own station written above are inspected, and the own station is confirmed as the destination. When the data specified as exists, the called remote station sets the connectable state flag in the relevant data in the connection control memory to connectable if the called remote station is in the connectable state, and performs exchange control. By reading the data into the exchange control slot when the scanning address of the slot indicates the address of the connection control memory, all remote stations can be connected by means of writing from the exchange control slot to the connection control memory. Write to the control memory, and the calling remote station confirms that the connection request flag set by the local station exists in the data at the address location corresponding to the local station number in the connection control memory of the local station that was written above, and that the destination station If it is detected that there is a connection ready status flag set by The contents of the connection control memory are written to the connection control memories of all remote stations by means of reading the contents of the connection control memory to the exchange control slot and means of writing from the exchange control slot to the connection control memory. When it is detected that the connection request, connection possible, and calling party communication flags are set for the own station in the stored local station connection control memory, the target address is set at the corresponding address location in the connection control memory. The calling side communication flag is set, and the contents of the connection control memory are written to the connection control memory of all remote stations simultaneously by the means for reading the contents of the connection control memory to the exchange control slot and the means for writing from the exchange control slot to the connection control memory. The calling side remote station sets the communication start state in the calling side remote station, and the calling side remote station stores both the calling side communication and the called side communication in the address position corresponding to the own station number in the local station connection control memory written above. A switching device for a loop transmission system, characterized in that when it is detected that both flags are set, communication using the dedicated communication slot is started.