JPH0440137A - Line exchange type lan - Google Patents

Abstract

PURPOSE:To inform each reception station of the presence of communication abnormality by inserting a symbol showing the communication abnormality, instead of a symbol encoding a stream data, to the relevant slot of a frame and transmitting the frame when the communication abnormality is detected. CONSTITUTION:When an abnormal token or frame is detected or when a normal token or frame is not detected within fixed time, a purge processing is executed to recover a ring. When the ring is not recovered by a frame token processing, a beacon processing is started and the communication station detecting the abnormality generates the frame to announcing the spot and cause of the abnor mality and transmits it. Then, the communication station receiving the normal beacon frame is escaped from the beacon processing and at an interval to an upstream adjacent station, only the communication station detecting the abnormality is remained. Thus, the communication station identifying the abnor mality or generating the abnormality can be controlled to be separated from the ring.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention relates to a circuit-switched LAN (internal information network) in which a plurality of communication stations are connected in a ring shape through a transmission path and stream data is communicated between these stations. communication network).

"Conventional technology" Traditionally, when playing songs and producing music sources in a music production studio, audio data that is digitally converted from voices and sounds generated from acoustic instruments, and audio data generated from electronic instruments such as synthesizers are used. The performance control data expressed by the key-on signal, key-off signal, etc. are handled separately.

"Problems to be Solved by the Invention" By the way, in the production of conventional music sources, audio data and performance control data are handled separately, as described above, but this is based on the following reasons. There is.

First, performance control data, such as key-on signals and key-off signals, can be transmitted by sending a signal of a predetermined length at the time each signal is generated, so packets have traditionally been used to transmit computer data. Replaceable LA
N can be used as is. Therefore, only one communication cable is required.

On the other hand, for stream data that is continuous in time series such as audio data, data of a predetermined length, for example, 24-bit data, must be continuously sent at predetermined sampling timings. This is not a problem if the transmission speed is fast enough and the data is small, but
There is a problem when multiple lines are overlapped. For example, although the transmission speed of audio data is relatively low, the tolerance for transmission delay is extremely small, making it impossible to transmit audio data in real time.

Therefore, a dedicated line is required for each audio data, and in the past, communication cables for audio data were required for the number of sources or more.

This invention was made in view of the above-mentioned circumstances, and provides a circuit-switched LAN that can transmit multiple stream data through one transmission path with a simple configuration and protocol without reducing communication efficiency. The purpose is to

``Means for Solving the Problems'' The invention as claimed in claim 1 provides a circuit-switched LAN in which a plurality of communication stations are connected in a ring shape through a transmission path and stream data is communicated between these stations. encodes the stream data and synchronization data for synchronizing the stream data into symbols using the same encoding method, and encodes these symbols into multiple frames having multiple slots yh corresponding to multiple channels. The receiving station divides and inserts the frames into preset slots with the same number and periodically transmits them through the transmission path, and the receiving station receives the frames (D in the slots with the same number) transmitted through the transmission path. The present invention is characterized in that the symbols of are connected together to extract stream data, and this stream data is output in synchronization with the synchronization data.

Further, in the invention according to claim 2, in the invention according to claim 1, when the transmitting station does not have the stream data to be transmitted to its own station, the transmitting station uses the symbol encoded with the stream data instead of the symbol encoded with the stream data. It is characterized in that a symbol indicating that there is no stream data is inserted into the corresponding slot of the frame and transmitted.

Further, in the invention according to claim 3, in the invention according to claim 1 or 2, when the transmitting station detects a communication abnormality, the transmission station replaces the symbol encoded with the stream data with the communication abnormality. It is characterized in that a symbol indicating the above is inserted into the corresponding slot of the frame and transmitted.

"Operation" According to the invention described in claim 1, the transmitting station first encodes the stream data and the synchronization data into symbols using the same encoding method. Then, these symbols are divided and inserted into slots of the same preset number in each frame, and are periodically transmitted via the transmission path.

On the other hand, the receiving station connects the symbols in the same numbered slots of each frame transmitted via the transmission path, extracts stream data, synchronizes the stream data with the synchronization data, and outputs the stream data.

According to the invention set forth in claim 2, in the circuit-switched LAN according to the invention set forth in claim 1, when there is no stream data to be transmitted to the transmitting station, the transmitting station encodes the stream data. Instead of a symbol, a symbol indicating that there is no stream data is inserted into the corresponding slot of the frame and transmitted.

Furthermore, according to the invention set forth in claim 3, in the circuit-switched LAN according to the invention set forth in claim 1 or claim 2, when the transmitting station detects a communication abnormality, Instead, a symbol indicating a communication abnormality is inserted into the corresponding slot of the frame and transmitted. Therefore, each receiving station can know that there is a communication abnormality.

"Embodiment" Before describing an embodiment of the present invention, the basic idea for solving the above-mentioned problem will be explained.

The present applicants have previously jointly and independently proposed a token ring based packet-switched LAN for real-time applications.

Here, the configuration of the packet-switched LAN connection section used in the above-mentioned packet-switched LAN and controls the transmission and reception of signals will be described.

FIG. 5 is a block diagram showing the configuration of a packet-switched LAN connection section and its peripheral devices. 1 is a connector connected to a transmission line such as an optical fiber cable, and 2 is a receiver, which receives the signal transmitted via the transmission line and connector 1 and outputs a signal SP, l with a width of 1 via). .

Further, 3 is a decoding unit, which decodes the frame/token pit string F/TBA from the signal SP□, and also decodes the internal P
The LL circuit extracts the bit clock CK from the signal SPR and outputs it.

Furthermore, 4 is a packet-switched LAN connection section. In the packet-switched LAN connection section 4, 5 is a received bit analysis section, which analyzes the frame/token pit string F/TB.
Constantly inspect A, frame/token pit row F/TE
Detection of timing signal STH related to start/end etc. of A, detection and generation of ring priority P7 and reservation priority R, , and frame pit string F constituting the frame.
Extract BA. Here, the ring priority P is the current priority of the token or frame transmitted on the transmission path, and the reservation priority Rt is used by the communication station to reserve data transmission according to the priority of data within its own station. This is the priority used for

6 is a reception control unit which inputs the frame bit string FB^, judges whether this frame bit string FBA is addressed to the local station, and outputs received data D3 addressed to the local station. Reference numeral 7 denotes a received data output unit which receives received data D6 and outputs received data DR based on a received control signal RCTL output from a data processing unit (not shown).

Reference numeral 8 designates a bi-y) delay unit that rewrites bits during relaying of the frame/token bit string F/TBA, and 9 designates a transmission data input unit, which inputs a transmission control signal TCTL to a data processing unit (not shown). It inputs transmission data DT to be transmitted outputted from a data processing section, and outputs transmission data DT based on a data request signal DR outputted from a transmission control section 10, which will be described later.

Reference numeral 10 denotes a transmission control unit which generates a token pit string TBA and also sends a data request signal DR to the transmission data input unit 9 based on the transmission instruction signal TS and transmission end signal TE output from the transmission data input unit 9. By outputting the transmission data DT, the frame bit string FBA is generated and output according to the token ring protocol.

This frame bit string FBA is generated by transmitting data DT
This is performed based on the data priority P extracted from the received bit analysis section 5, the ring priority P1, the reservation priority Rr, and the timing signal STN output from the received bit analysis section 5.

Reference numeral 11 denotes a transmission reservation unit, which inputs the larger of the reservation priority R and the data priority P output from the transmission control unit 10, and outputs a value corresponding to the priority to the bit delay unit 8. Set bit R4 of the reservation index of the frame/token pit row F/TBA that is being passed. 12 is a frame/token bit string F/TB output from the bit delay unit 8
This is a transmission selection section that selects and outputs either one of the frame/token bit strings F/TBA output from the transmitter A and the transmitter a section 10. Note that this selection is made by the transmission control unit 10.
This is done based on the selection signal SSKL output from the.

13 is a frame/token bit string F output from the transmission selection section 12 of the packet-switched LAN connection section 4.
/T Encoding unit that encodes EA, 14 is encoding unit 13
This is a transmitter that inputs the output signal SPa of and transmits the signal S■ to another communication station via a transmission line.

For details of the above-mentioned packet-switched LAN, please refer to the specifications and drawings attached to the respective applications of Japanese Patent Application No. 1-342291 to Japanese Patent Application No. 1-342295 and Japanese Patent Application No. 1-343211. .

By the way, the packet switching type LAN connection section 4 mentioned above is
Since it can be configured using an SI (large scale integrated circuit), commands can be easily communicated by using this LSI in a packet-switched LAN.

Therefore, in the present invention, command communication is performed using the packet-switched LAN connection section 4 described above, and the LAN for communicating commands and stream data is as follows:
The LAN uses a hybrid protocol of a line-switched protocol for stream data and a bucket-switched protocol for commands.

Next, the topology of the LAN is the packet-switched L
Due to the use of the AN connection section 4, it is of a ring type. Furthermore, the transmission method is a baseband transmission method.

There are two ways of thinking about hybridization as shown below.

The first idea is to put packet-switched LAN data on a circuit-switched LAN channel. first,
This circuit-switched LAN protocol provides N channels that allow one-to-many (or one-to-one) communication.

Therefore, N independent stream data can be handled. Furthermore, it is assumed that the stream data is transmitted using a frame having N slots corresponding to N channels, as shown in FIG.

Then, each transmitting station divides and inserts stream data into preset slots among the N slots of each frame, and time-division multiplexes this frame with sufficient timing to transmit the stream data. to be transmitted periodically.

On the other hand, each receiving station assembles stream data for that channel by connecting the symbols in the same numbered slots of each frame.

This allows data transmission by creating one channel for one stream of data. For example, in FIG. 6, slot 1 of frame 1
The stream data of channel 1 is assembled by connecting the data of slot 1 of frame 1 and the data of slot 1 of frame 2, and the stream data of channel 2 is assembled by connecting the data of slot 2 of frame 1 and the data of slot 2 of frame 2. stream data is assembled.

Furthermore, data in a packet-switched LAN is transmitted by being divided and inserted into the slots of each frame.

Thereby, commands and stream data can be transmitted through one transmission path.

Here, FIG. 7 shows an example of the configuration of a control section for signal transmission and reception based on the first concept. In this figure, 1 is a connector, 4 is the above-mentioned packet-switched LAN connection section, and 15 is a circuit-switched LAN connection section that is used for a circuit-switched LAN and controls the transmission and reception of signals.

The second idea is to combine circuit-switched LAN data and packet-switched LAN data into one data. Here, an example of each data encoding method is shown below.

000: O-level data of circuit-switched LAN 001: Level data of circuit-switched LAN 010: 0-level data of packet-switched LAN 011: Packet-switched LAN
Therefore, by encoding circuit-switched LAN data and packet-switched LAN data using the same encoding method, the respective data can be superimposed and transmitted as one data. At the same time, each piece of data can be separated from the superimposed data.

Here, FIG. 8 shows an example of the configuration of a data transmission/reception control section based on the second concept. In this figure, parts corresponding to those in FIG. 7 are given the same reference numerals, and their explanations will be omitted. In FIG. 8, 16 is a shunt/combiner, which separates the signal transmitted via the connector 1 into a signal for the packet-switched LAN and a signal for the circuit-switched LAN, and also connects the packet-switched LAN. The signals output from each of the section 4 and the line-switched LAN connection section 15 are combined and transmitted as one signal via the connector 1. Note that the circuit-switched LAN connection section 15 in FIG. 8 may have a different configuration from the circuit-switched LAN connection section 15 in FIG. 7.

By adopting the concept described above, stream data and commands such as musical tone control data can be communicated over one LAN with a simple configuration and protocol without reducing communication efficiency.

(1) Explanation of the first idea 7) The IJ-1 data encoding method is that when each bit of stream data is "0", there is no level change, and when each bit is "1", the level changes. Invert NRZ I
(Non Return to Zero Inv
erted) and 4 which represents 4 bits of data with 5 bits.
B15B encoding method is combined. FIG. 9 shows an example of the encoding method described above. In this figure, the symbol "+" means that the polarity is reversed, and the symbol "-" means that the polarity is not reversed.

In FIG. 9, (0) to (F) are symbols for data, and (BST) to (FE) are synchronization symbols for frames, which are used to find the frame. still,
The structure of the frame will be described later with reference to FIG. 10. Further, (NC) to (OV) are synchronization symbols for data for each slot.

In FIG. 9, (reservation) means that the use is not currently considered, but it is reserved for future use.

Next, the structure of a frame sent between each communication station will be explained using FIG. 10. The frame is of fixed length, starting with a frame start sync symbol (FS), followed by N slots (corresponding to N channels), and ending with a frame end sync symbol (FE). A preamble (PRA) is inserted between frames.

Furthermore, the size of one slot is one symbol, and this slot contains data symbols from (0) to (F) mentioned above, and a symbol indicating that there is no data in the slot (hereinafter referred to as a no data symbol). ) (NC),
A sample synchronization start symbol (C8), a data error symbol (ER) and a non-data symbol of the transmit buffer overflow symbol (OV) are entered. still,
At each receiving station, if symbols in slots with the same number of each frame L/-A are connected, for example, 2
This is 4-bit audio data, but it is necessary to synchronize this data, so the non-data symbol (
NC) to (OV) are used for data synchronization.

As mentioned above, by encoding the symbols used for data synchronization together with the data, data synchronization symbols (NC) to (OV) can be used at the same level in frames and channels, improving communication efficiency. As the speed increases, the circuit configuration also becomes simpler, since it is no longer necessary to decode further data and synchronization data from these signals.

Next, a description will be given of the expression of audio data, which is stream data obtained by connecting /ports in slots with the same number of frames. FIG. 11 shows an example of the format of audio data. The sample synchronization start symbol (CS) described above indicates the separation of each sample, and six data symbols (Do-D5
) by 24-bit PCM (Pulse C
ode Modulation) value. The no data symbol (NC) may be placed anywhere in the symbol string, and is used to adjust the speed of regularly transmitted slots and the speed of irregularly generated audio data.

Also, musical tone control data is considered as bucket-switching LAN data, which is another data obtained by connecting symbols in slots with the same number of frames. Like the audio data, this data is also decoded from symbols in specific slots (described later) of the frame based on the encoding method described above. As in the case of audio data, one data symbol allows 4 vias 1
represents the signal for - minutes. The no-data symbol (NC) may be placed anywhere in the symbol string, and is used to adjust the speed of the sound control data and the speed of the tone control data.

In addition, the data of the bucket exchange type LAN is used for musical tone control,
It is also used for ring failure recovery. When the /< bus of the bucket-switched LAN shifts to a forced transmission state due to an abnormality in the ring, the communication station stops repeating frames and shifts to a forced transmission state of a frame carrying only the channel number corresponding to this data. The data of the packet-switched LAN is also used for maintenance such as channel assignment in the circuit-switched LAN. For details on the data format and usage of the LAN, please refer to the specification and drawings attached to the above-mentioned Japanese Patent Application No. 1-342291.

By the way, unlike audio data, data on a bucket-switched LAN is originally something that is repeated by each communication station on the LAN, so all communication stations use the same assigned slot (channel) to transmit and receive data. It is necessary to repeat the data. This repeat processing causes a delay of at least one frame at each communication station, but the delay can be kept to a minimum by assigning multiple slots/sotos to the data of the slot/node switching type LAN. .

An example to which the first concept is applied will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a ring-type LAN according to an embodiment to which the first concept is applied. In FIG. 1, 171 to 174 are communication stations that perform data communication with each other, and communication stations 17. is a mask station and communication station 1 that periodically transmits and collects frames.
7. 174 are slave stations that perform reception processing and transmission processing without repeating frames. 18 is communication station 1
7. ~17. This is a transmission line such as an optical fiber cable that connects the two in a ring shape.

Here, FIG. 2 shows a block diagram of the configuration of the communication station 17 of FIG. 1. In this figure, 1 is a connector, and 19 is a frame F having the format shown in FIG.
15 is the above-mentioned line-switched LAN connection section, 4 is the above-mentioned packet-switched LAN connection section, and 21 is a musical tone control data processing section. Processing of musical tone control data D3 to be output and musical tone control data DT to be transmitted to other communication stations 17
processing.

Further, 22 is an audio data processing section, which processes audio data D A output from the circuit-switched LAN connection section 15.
It processes audio data DAT to be transmitted to other communication stations 17. Reference numeral 23 denotes an encoding unit that encodes the frame F5 outputted from the line-switched LAN connection unit 15 into a transmission signal and transmits it via the connector 1 and the transmission line 18.

Further, in the line-switched LAN connection section 15, 24 is a reception control section, which extracts symbols from the audio data slot assigned to the local station and the bucket-switched LAN slot of each input frame F5, and replaces them with the symbols. In addition to inserting a no data symbol (NC) into
A symbol string is generated for each slot, and a packet-switched L
It is divided into a symbol string S□ for AN and audio data DAR (see FIG. 11) and output. Of these, the audio data DAR is output after waiting for a sample start synchronization symbol (C3), as shown in FIG.

3 is a decoding unit, which converts the input symbol string 5PII into a frame/token bit string F/of the packet switched LAN.
It is decoded into TBA and output in synchronization with clock CKa.

13 is an encoding unit, and a packet-switched LAN connection unit 4
The frame/token focus sequence F/TBA output in synchronization with the clock CKT is inputted to generate the symbol sequence SPT.
Encode and output. 27 is a transmission control unit which inputs the audio data DAT and the symbol string SPT output from the encoder 13, and inserts these into predetermined slots of each frame F5 output from the reception control unit 24. and output it.

Here, the total number of slots per frame is 1
There are five slots, and the allocation of each slot is determined in advance as follows.

(1) Audio data transmission slot 1: mask station 17. -Slave station 17° slot 2° slave station 17! -Slave station 17° slot 3
Nislepe station 173 → slave station 174 slot 4 Nislepe station 174 → master station 17° slot 6: master station 17I - slave station l 7° slot 7 master station 17
．． -Sley 7' station 17.

Slot 9. Slave station 17. - Master station 17.

Slot 10 - Slave station 17. - Slave station 174 slot 11 Slave station 173 → Master station 171 slot 13 / Slave station 173 - Slave station 17° slot 14 Slave station 174 - Slave station 17° slot 1
5. Slave station 174-slave station 17° (2) Musical tone control data transmission slot 5, 8.12 In such a configuration, each communication station 17. . . . 17 will now explain the operation of communicating audio data and musical tone control data.

First, mask station 17. In the packet-switched LAN
Musical tone control data DT such as a key-on signal is sent from the musical tone control data processing section 21 (see FIG. 1) based on the output timing of the transmission control signal TCTL outputted from the transmission data input section 9 (see FIG. 5) of the connection section 4. is output and input to the transmission data input section 9 of the packet-switched LAN connection section 4.

Next, the packet-switched LAN connection section 4 converts the frame/token hit string F based on the musical tone control data DT.
/TBA is generated, this frame/token bit string F/TBA is output in synchronization with the output cross CKa of the packet-switched LAN connection section 4, and is sent to the encoding section 13 of the circuit-switched LAN connection section 15. input (see Figure 2). For details of the operation of the packet-switched LAN connection section 4, please refer to the specification and drawings attached to Japanese Patent Application No. 1-342291.

The frame/token bit string F/TB is then encoded into a symbol string SPT by the encoding section 13 based on the encoding method shown in FIG. 9, and then input to the transmission control section 27.

Next, the / symbol sequence SPT is divided and inserted into slots 58 and 12 of each frame F5 generated by the transmission control unit 27.

On the other hand, the 24-bit audio data DAT encoded in the audio data processing section 22 is transmitted to the slave station 17. The audio data to be transmitted to the slave station 173 is placed in slot 1 of each frame F5, and the audio data to be transmitted to the slave station 173 is placed in slot 6.
The audio data to be transmitted to the slave station 174 is divided into slots 7 and inserted.

Also, since slots 2-4.9-]1 and 13-]5 of each frame F5 are used by other slave stations 17-174, no data holes (NC) are inserted.

Frame F5 in which the / symbol is inserted into each slot in this way is output from the transmission control section 27, and is sent to the encoding section 2.
After being encoded into a transmission signal at 17.3, it is sent to the slave station 17. ~174 periodically.

Next, slave station 17. In the decoding section 19 , a frame Fs is decoded from the signal transmitted via the transmission line 18 and the connector 1 , outputted, and inputted to the line-switched LAN connection section 15 .

Then, in the reception control unit 24, the symbol of the slot assigned to the own station regarding the audio data, in this case, slot 1, is extracted from among the slots 1 to 15 of each input frame F5, and the symbol of the slot 1 is extracted. A no data symbol (NC) is inserted.

Further, the extracted symbols are stored one after another in the internal memory of the reception control unit 24, and then outputted as audio data DAR in synchronization with the sample synchronization symbol (CS).

In addition, the reception control unit 24 extracts the symbols divided and inserted into slots 5, 8, and 12 regarding the musical tone control data of each frame F5, and also extracts the no data symbols (NC ) is inserted.

Further, the extracted symbols are connected and sequentially output as a symbol string SPR.

Next, the symbol string SPR is decoded into a frame/token bit string F/TBA in the decoding section 3, and then outputted in synchronization with the clock CKR. F and T are input to the switching type LAN connection section 4.

At this time, if no data symbols (NC) are inserted in slots 5, 8, and 12 of each frame, that is, if the mask station 17. If information regarding musical tone control data is not transmitted from the decoding section 3, the clock CK is not output from the decoding section 3.

Therefore, the frame/token bit string F/TBA is not input to the packet-switched LAN connection section 4.

When the frame/token bit string F/TBA is input to the packet-switched LAN connection section 4, the received bit analysis section 5 (fifth packet) of the packet-switched LAN connection section 4
(see figure), frame/token bit string F/T
A frame bit string FBA constituting a packet-switched LAN frame is extracted from BA. Next, in the reception control unit 6, the frame/token bit string F/T
Received data D is extracted from B and input to the received data output section 7. This received data D3 is outputted from the received data output section 7 based on the reception control signal RCTL outputted from the musical tone control data processing section 21, inputted to the musical tone control data processing section 21, and processed.

Here, slave station 17. If it is time to acquire a token and send musical tone control data,
Transmission data input section 9 of packet-switched LAN connection section 4
Musical tone control data DT is outputted from the musical tone control data processing section 21 based on the transmission control signal TCTL outputted from the TCTL, and is inputted to the packet-switched LAN connection section 4.

Next, in the packet-switched LAN connection section 4, a frame bit string FBA is generated based on the musical tone control I data D1, and then output in synchronization with the output clock CKT. (see figure).

Also, slave station 17. frame, or
If the token is simply repeated, the packet-switched LAN connection unit 4 outputs the repeated frame/token bit string F/TBA in synchronization with the output clock CKT, and connects it to the circuit-switched LAN.
The signal is input to the connection section 15 (see FIG. 2).

The frame/token bit string F/TB is then encoded into a symbol string SPT by the encoding section 13, and then input to the transmission control section 27.

Next, the /frame sequence SPT is divided and inserted into slots 5, 8, and 12 of each frame F5 in the transmission control unit 27.

On the other hand, slave station 17. If it is not the timing to output the frame/token bit string F/TBA, the output clock CKT is not output from the packet-switched LAN connection section 4.

Therefore, since the symbol sequence SPT is not output from the encoding unit 13, the transmission control unit 27 continues to insert no data 7 symbols (NC) into slots 5, 8, and 12 of each frame F5. .

Also, slave station 17. Audio data D to be transmitted to each communication station 17° and 173.174 at
If there is an AT, this audio data DAT is
The signal is output from the audio data processing section 22 and inputted to the circuit-switched LAN connection section 15.

Then, the transmission control section 27 of the circuit-switched LAN connection section 15
In each slot of each frame Fs output from the reception control unit 24, the slave station 17. The audio data DA to be sent to slave station 1 is placed in slot 2.
The audio data to be sent to slot 74 is sent to slot 10,
Audio data to be transmitted to the mask station 17° is divided into slots 9 and inserted.

On the other hand, slave station 17. Audio data D to be transmitted to each communication station 17° and 173.174 at
In the absence of AT, slot 2.9 of each frame Fs
and 10, no data symbols (NC) remain inserted.

The frame Fs with symbols inserted into each slot in this way is output from the transmission control section 27, and is sent to the encoding section 2.
After being encoded into a transmission signal at the communication station 17 . ．． 17. and 17
4.

Communication station 17 explained above. The operation in each communication station 1
73 and 174 are performed in the same manner, so the explanation thereof will be omitted.

Then, master station 17. The encoded and transmitted frame Fs goes around the transmission path 18 and returns to the mask station 17 □
When input to mask station 17. The above-described reception processing and transmission processing are also performed in , and the frame Fs is encoded and transmitted again.

The operation explained above is performed by each communication station 17. By repeating steps 174 to 174, musical tone control data and audio data are communicated using one transmission path 18.

By the way, if there is an abnormality in a certain slot of the frame F5 collected at the mask station 171, the mask station 17. Then, a data error symbol (ER) shown in FIG. 9 is inserted into that slot and the frame is transmitted.

In addition, each communication station 17. When the transmission buffer corresponding to a certain slot of frame F6 transmitted in ~174 overflows, each communication station 17, ~174 inserts an overflow symbol (OV) shown in FIG. Fs is transmitted.

Next, when the above-mentioned communication is being performed, for example, the first
Communication station 17 in the figure. and communication station 17. A failure recovery operation when a communication failure occurs, such as a disconnection of the transmission line 18 for some reason, will be described.

In order to manage each communication station in a ring-shaped packet switching LAN, the applicant has developed a communication system in which each communication station grasps the address of its upstream adjacent communication station (hereinafter referred to as upstream adjacent station address). We previously jointly proposed a station management method (see the specification and drawings attached to Japanese Patent Application No. 1-342293).

Here, this communication station management method will be explained.

First, a masked station (hereinafter referred to as an active monitor) periodically sends a special frame (hereinafter referred to as an A
MP frames) are transmitted.

On the other hand, each downstream communication station (hereinafter referred to as a standby monitor) imports the address in the received AMP frame into its own station, and transmits an AMP frame with that address replaced with its own address to the next station.

And the active monitor shows A who has gone around the ring.
Collects the MP frame and imports the address in the AMP frame into its own station.

According to the method described above, each communication station can always know the address of an upstream adjacent station.

By the way, if a certain standby monitor cannot receive the above-mentioned AMP frame within a certain period of time, the standby monitor detects that the active monitor is not operating normally.

In this case, the standby monitor that has detected an abnormality in the active monitor forcibly transmits a special frame (hereinafter referred to as a claim token frame) that is issued when the active monitor cannot be detected.

As a result, the active monitor that received the claim token frame ceases to be an active monitor. When all communication stations including this active monitor receive the claim token frame, they participate in the competition for selecting a new active monitor.

Next, the new active monitor selected through the above-described competition restores the ring by purging the ring. In this purge process, the active monitor detects abnormal tokens or frames that have been transmitted on the ring for one or more rounds, removes them, and generates and transmits new tokens. Then, other communication stations synchronize with this process to initialize the ring. The processing in the standby monitor described above is called claim token processing.

In addition, if the active monitor detects an abnormality, for example, if it detects an abnormal token or frame as described above, or if it does not detect a normal token or frame within a certain period of time, it performs the purge process described above. , restore the ring.

However, if the ring is not restored by the purge process, the process proceeds directly to the claim token process.

Furthermore, if the ring is not restored by claim token processing, the process shifts to beacon processing.

In this beacon processing, first, a communication station that has detected an abnormality generates and transmits a frame (hereinafter referred to as a beacon frame) for notifying the location of the abnormality and its cause. Then, the communication station that has received the normal beacon frame exits the beacon process, leaving only the communication station that detected the abnormality between it and the upstream adjacent station. This makes it possible to identify the location of the abnormality and control the separation of the communication station with the abnormality from the ring. Then, the ring may be restored when the abnormal communication station leaves the ring automatically or according to instructions from the user of the communication station.

Note that since the period for detecting an abnormality by the active monitor is usually shorter than the period for detecting an abnormality by the standby monitor, the active monitor detects the abnormality first.

Therefore, the above-described concept of recovery from a communication failure is also adopted in a LAN in which stream data and commands can be communicated through one transmission path.

Normally, when normal communication is being performed, the slave station simply repeats the frame F3 transmitted from the mask station or the upstream adjacent station, and performs reception processing and transmission processing at that time. In addition, the clock CKT output from the switched LAN connection section 4 of the slave station is a pit clock CK extracted by the P L, L circuit section in the decoding section 3 of the line switched LAN connection section 15. .

However, when the slave station detects the abnormality using the method described above, the transmission control unit 27 detects the transmitted frame F.
Instead of repeating s, a unique frame is generated and this frame is forcibly transmitted in synchronization with a crystal oscillated clock inside the packet-switched LAN connection section 4. At this time, this frame includes packet-switched LA.
Only the symbol obtained by encoding the frame/token bit string F/TBA output from the N connection unit 4 is inserted into the corresponding slot. After this, the failure recovery is performed by the above-mentioned failure recovery function of the packet-switched LAN connection unit 4.
Rebuild your network.

As explained above, by using the failure recovery function of a packet-switched LAN, frames can be transmitted even if there is a failure in the LAN, so there is no need to consider communication stoppage. Further, the circuit-switched LAN connection section 15 without a failure recovery function can be used as is.

In addition, maintenance of the entire LAN is performed using a packet-switched LA.
This is done using the frame FB8 input/output to the N connection section 4.

Furthermore, in the above explanation, an example was shown in which each slot of a frame input/output to the circuit-switched LAN connection section 15 is set in advance. This can be done using the input/output frame FBA. By doing this, each communication station 17. In steps 174 to 174, it is possible to appropriately deal with changing communication requests.

(2) Explanation of the second way of thinking A self-synchronized signal in which a clock is superimposed on data is used as the signal transmitted through the transmission line, and the (0/Level) command and stream data encoding method are both In order to mix the numbers, an encoding method is used in which three bits represent one symbol. In this case, if framing data is also encoded, communication efficiency will decrease. For example, since 2 bits are required to represent three states: data (0), data (1), and framing data, communication efficiency is reduced to 1/2. However, since there are not many types of data for framing, if 4-bit data is expressed in 5 bits, the decrease in communication efficiency will be 41
It can be kept to 5.

Here, an example of the encoding method described above is shown in FIG.

In this figure, + indicates that the polarity is reversed, and - indicates that the polarity is not reversed. Also, (ND) is a symbol (
(hereinafter referred to as a no-data symbol).

Next, the data will be converted into bit frames according to the format shown in FIG. 13 and transmitted. This bit frame is of undefined length and has a bit string starting synchronization symbol (BS).
It starts with , and consists of a bit string consisting of (PO), (Pl), (So), (Sl), and (ND). A preamble (PRA) is inserted between bit frames, and the end of the bit string is detected by detecting the preamble (PRA).

Further, a bit string start synchronization symbol (BS) is periodically inserted to enable bit synchronization.

Note that since the symbols are in bit units, the position within the bit frame does not matter as long as the order of the symbols matches the original data.

By the way, the following two processing procedures can be considered for generating and recovering bit frames.

In the first processing procedure, bit frames are generated and collected between adjacent stations, and the bit frames are not repeated. In the case of this processing procedure, each communication station collects the bit frame transmitted from the upstream adjacent station, generates a new bit frame, and transmits it to the downstream adjacent station using the clock oscillating in the local station. At this time, each station captures data symbols from the received bit frame and writes data symbols to be transmitted by the station into the bit frame to be transmitted. In addition, if there is no data,
Instead of data symbols, no data symbols (ND
).

In the second processing procedure, similar to the first concept described above, the mask station generates and collects bit frames, and the slave station repeats the bit frames and performs reception processing and transmission processing.

Further, although any protocol may be used for the circuit-switched LAN, in the following explanation, the protocol used in the first concept described above will be used.

An example of the second concept will be described below with reference to the drawings. Here, consider audio data as stream data and musical tone control data as commands.

(1) Description of an embodiment using the first processing procedure First, it is assumed that the configuration of the ring type LAN is the same as that shown in FIG. However, there is no distinction between mask stations and slave stations, and each communication station generates and transmits a bit frame.

Next, a block diagram of the configuration of the communication station 17 is shown in FIG.

In this figure, parts corresponding to those in FIG. 2 are given the same reference numerals, and their explanations will be omitted. In Figure 3,
28 is a connector connected to the transmission line 18 arranged between the upstream adjacent station, and 29 is a decoding unit, which decodes the bit string from the signal transmitted via the transmission line 18 and the connector 28 and starts the bit string. Detect synchronization symbol (BS),
bit frame F, bit string start synchronization symbol (BS
) is output in synchronization with

Further, 30 is a shunt, which inputs the bit frame F, extracts only the symbols for the packet-switched LAN, and generates and outputs a new symbol string 5Pi1. 31 is a decoding unit, which decodes the input symbol string S□ into the frame/token bit string F/TB of the packet-switched LAN and outputs it to the packet-switched LAN connection unit 4; 3
Reference numeral 2 denotes an encoding section, which inputs the frame/token bit string F/TBA output from the packet-switched LAN connection section 4, encodes it into a symbol string SpA, and outputs it.

Furthermore, 33 is a shunt, which inputs the bit frame F, extracts only the symbols for the circuit-switched LAN, and generates and outputs a new symbol string SSB. 34 is a circuit-switched LAN connection unit, which inputs the symbol string SSI and outputs the symbol string S ss according to a predetermined processing procedure.
is processed and replaced, and a new symbol string SST is output. 35 is an audio data processing unit, which processes audio data D output from the line-switched LAN connection unit 34;
It processes AI1 and audio data DA1 to be transmitted to another communication station 17.

In addition, 36 is a confluencer, and 37 is an encoder. The confluencer 36 inputs the symbol strings SPT and ssa and temporarily stores them in an internal memory in bit units.

When the symbol request signal SRQ output from the encoding section 37 is input, the symbol strings SPT and SsT are taken out from the memory and output. At this time, if the symbol strings spy and SST do not exist in the memory, a no data symbol (ND) is output. The encoding unit 37 encodes the symbol strings SPT and Ssy output from the combiner 36.
is input to generate a bit frame F in which a bit string start synchronization symbol (BS) is periodically inserted, and the bit frame FB is encoded into a transmission signal and transmitted via the connector 38 and the transmission line 18.

In such a configuration, each communication station 17. The operation of communicating the audio data and musical tone control take in step 174 will be explained.

First, communication station 17. 1) Switchable LAN
Based on the output timing of the transmission control signal TCTL output from the transmission data input section 9 (see FIG. 5) of the connection section 4, the musical tone control data processing section 21 (see FIG. 3) generates musical tone control data DT such as a key-on signal. is output and input to the transmission data input section 9 of the packet-switched LAN connection section 4.

Next, in the packet-switched LAN connection section 4, the musical tone control data D? Frame/token bit string F based on
After /TBA is generated, this frame/token pit string F/TBA is output in synchronization with the output clock CK_T of the packet-switched LAN connection unit 4 and input to the encoding unit 32.

Then, the frame/token bit string F/TB5 is encoded into a symbol string SPT by the encoding unit 32 based on the encoding method shown in FIG. Temporarily stored in memory.

On the other hand, the 24-bit audio data DAT is output from the audio data processing section 35 and sent to the circuit-switched LAN.
After being input to the connection unit 34 and encoded into a symbol string SIT based on the encoding method shown in FIG.
6 and temporarily stored in the internal memory in bit units.

Next, when the symbol request signal SRQ output from the encoding section 37 is inputted to the combiner 36, the symbol strings SpA and SST are taken out from the memory and output. At this time, symbol strings SP7 and SsT are stored in the memory.
If not, the 7-Gita symbol (
ND) is output.

Then, the encoding unit 37 generates a bit frame FB in which a bit string start synchronization symbol (BS) synchronized with an internally oscillated clock is periodically inserted based on the symbol strings SPT and SsT. is encoded into a transmission signal and transmitted via connector 38 and transmission line 18.

Next, communication station 17. In the decoding unit 29 of the transmission line 18
A symbol string is decoded from the signal transmitted via the connector 28. Then, a bit string start synchronization symbol (BS) is detected from the symbol string, outputted as a bit frame FB in synchronization with the bit string start synchronization symbol (BS), and input to the shunts 30 and 33.

Then, in the flow divider 30, the bit frame FB color bucket exchange pear 1. Only symbols for AN are extracted to generate a new symbol string SPR.

This symbol string S pm is converted into a packet-switched LAN frame/token bit string F/T in the decoding unit 31.
The data is decoded and output to the BA, and then input to the packet-switched LAN connection section 4.

Next, in the received bit analysis section 5 of the packet-switched LAN connection section 4, the frame/token bit string F/TBA is
A frame column FBA constituting a packet-switched LAN frame is extracted from the frame.

Next, the reception control section 6 extracts the reception data D from the frame/token bit string F/TBA and inputs it to the reception data output section 7. This reception data D8 is the reception control signal R output from the musical tone control data processing section 21.
Based on the CTL, the received data output section 7 outputs the received data, inputs it to the musical tone control data processing section 21, and processes it.

Here, communication station 17. When it is time to acquire a token and transmit musical tone control data, the musical tone control data processing section 21 receives a token based on the transmission control signal TCTL output from the transmission data input section 9 of the packet-switched LAN connection section 4. Musical tone control data DT is output and input to the packet-switched LAN connection section 4.

Next, the packet-switched LAN connection section 4 generates a frame bit string FBA based on the musical tone control data D, and then outputs it in synchronization with the output clock CK↑ and inputs it to the encoding section 32.

Also, communication station 17. If the frame or token is simply repeated, the packet-switched LAN connection section 4 outputs either the repeated frame/token bit string F/TBA or the output clock C.
It is output in synchronization with K-a and input to the encoding section 32.

And frame/token bit string F/T B6
is encoded into a symbol string S pt by the encoding unit 32, and then input to the confluencer 36, where it is temporarily stored in an internal memory in units of bits.

Also, communication station 17. If it is not the timing to output the frame/token bit string F/TBA,
Packet y) Output clock CK from switchable LAN connection section 4
Since T is not output, the encoding section 32 does not output the symbol string SPA.

-4, in the shunt 33, only symbols for the circuit switched LAN are extracted from the bit frame F6 to generate a new symbol string Ss++, and this symbol string SSB
is input to the circuit-switched LAN connection section 34.

Then, in the circuit-switched LAN connection section 34, audio data DAR addressed to the own station is extracted from the symbol string S according to a predetermined processing procedure and outputted to the audio data processing section 35. Further, if the audio data processing unit 35 has audio data DAT to be transmitted to each communication station 171 and 178.174, this audio data DAT is transmitted to the audio data processing unit 3.
5 and inputted to the line-switched LAN connection unit 34, a new symbol string SST is generated based on this audio data DAT, inputted to the combiner 36, and temporarily stored in the internal memory in bit units. Ru.

Also, communication station 17. At each communication station 17. and 17
．． ．． 17. If there is no audio data DA to be transmitted, the circuit switched LAN connection section 34 does not output the symbol string SST.

Next, when the symbol request signal S3° outputted from the encoding section 37 is inputted to the combiner 36, the symbol strings SPA and SsA are taken out from the memory and outputted. At this time, symbol strings S2A and SST are stored in the memory.
If there is no data symbol (ND), a no data symbol (ND) is output.

Then, the encoding unit 37 generates a bit frame F in which a bit string start synchronization frame (BS) synchronized with an internally oscillated clock is periodically inserted based on the symbol strings SPT and S5A. Bit frame F is encoded into a transmission signal and transmitted via connector 38 and transmission line 18.

Communication station 17 explained above. The operation in each communication station 1
7. and 174 are also performed in the same way, so the explanation thereof will be omitted.

The operation explained above is performed by each communication station 17. By repeating steps 174 to 174, musical tone control data and audio data are communicated using one transmission path 18.

In addition, in the above-mentioned embodiment, each communication station 17, to 17
4 generate the bit frame FB using their own clocks. For example, if the frequency of the communication station 17.0 clock is the highest and the frequency of the communication station 174 is the lowest, the communication station 17.4 generates the bit frame FB using its own clock. Data may get stuck in the input section. However, in this case, each communication station 17. By providing a data buffer in ~174, the length of each bit frame Fs may be adjusted.

(ii) Description of one embodiment of the second processing procedure First, it is assumed that the configuration of the ring type LAN is the same as that shown in FIG. Therefore, communication station 17. 17. is a mask station and a communication station that periodically transmits and collects frames. 174 are slave stations that perform reception processing and transmission processing while repeating frames. Also, mask station 17. The configuration is the same as that in FIG.

Next, FIG. 4 shows the slave station 17. A block diagram of the configuration of ~174 is shown. In this figure, parts corresponding to those in FIG. 3 are given the same reference numerals, and their explanations will be omitted. In FIG. 4, 39 is a shunt, and the bit frame F
B is input, extracts only the symbols for the packet-switched LAN, generates and outputs a symbol string of 5 PII, and replaces the extracted 7 symbols with a no-data symbol (N
D) is inserted into a new bit frame F'8.

Further, 40 is a shunt, which inputs the bit frame F', extracts only the symbols for circuit-switched LAN, generates and outputs a symbol string 55R, and replaces the extracted symbols with no-data symbols ( A new bit frame F1 into which the bit frame ND) is inserted is output.

Furthermore, 41 is a confluencer which inputs the symbol strings SPT and SgT and temporarily stores them in an internal memory in units of bits. Then, when the bit frame F"8 output from the shunt 40 is input and a no data symbol (ND) is detected in the bit frame F1B, the no data symbol (ND) is transferred from the memory to the symbol string S.
PT and SsT are replaced with the extracted symbol string S PT and SST, and a new Tana bit string SA is output. At this time, if there are no symbol strings SPT and SsT in the memory, then B.

The frame F6 is output as it is as a bit string sA.

In addition, 42 is an encoding section which inputs the bit string SA output from the confluencer 41, encodes the bit string SA into a transmission signal, and transmits it via the connector 38 and the transmission line 18.

In such a configuration, each communication station 17. The operation of communication of audio data and musical tone control data by 174 will be explained.

First, in the mask station 17□ of FIG.
Musical tone control data DT such as a key-on signal is outputted from the musical tone control data processing section 21 based on the output timing of the transmission control signal TCTL outputted from the packet-switched L.
The data is input to the transmission data input section 9 of the AN connection section 4.

Next, in the packet-switched LAN connection section 4, a frame/token bit string F is generated based on the musical tone control data D.
After /TBA is generated, this frame/token bit string F/TBA is outputted in synchronization with the output clock CK-7 of the packet-switched LAN connection section 4 and inputted to the encoding section 32.

The frame/token bit string F/TB6 is then encoded into a symbol string SPT by the encoding unit 32 based on the encoding method shown in FIG. is temporarily stored.

On the other hand, the 24-bit audio data processing section outputs the data from the audio data processing section 35 and converts it into a circuit-switched LAN.
After being input to the connection unit 34 and encoded into a symbol string SsT based on the encoding method shown in FIG.
and is temporarily stored in internal memory bit by bit.

Next, in the combiner 36, symbol request signals Si1. When input, the symbol strings Spa and SsT are taken out from the memory and output. At this time, the symbol strings S1 and S8T are stored in the memory.
If there is no data symbol (ND), a no data symbol (ND) is output.

Then, the encoding unit 37 generates a bit frame Fa in which a bit string start synchronization symbol (BS) synchronized with an internally oscillated clock is periodically inserted based on the symbol strings SPT and SsT. is encoded into a transmission signal and transmitted via connector 38 and transmission line 18.

Next, slave station 17. of FIG. In the decoding unit 29, a symbol string is decoded from the signal transmitted via the transmission path 18 and the connector 28, a bit string start synchronization symbol (BS) is detected from the symbol string, and a bit string start synchronization symbol (BS) is detected as a bit frame F. It is output in synchronization with the symbol (BS) and input to the shunt 39.

Then, in the shunt 39, only symbols for the packet-switched LAN are extracted from the bit frame FB, a new symbol string SPR is generated and output, and a no-data symbol (
A new bit frame F' into which ND) is inserted is output.

Next, the operation from when the symbol sequence SPR is input to the decoding unit 31 until the symbol sequence SPT output from the encoding unit 32 is input to the combiner 41 and temporarily stored in the internal memory is as described above. Operation from when the symbol string 5PII explained in the processing procedure of 1 is input to the decoding unit 31 until the symbol sequence SPA output from the encoding unit 32 is input to the combiner 36 and temporarily stored in the internal memory Since it is the same as that, the explanation thereof will be omitted.

On the other hand, in the shunt 40, only symbols for the circuit-switched LAN are extracted from the bit frame F', a new symbol string 5slI is generated and output, and a no-data symbol ( N.D.
) is inserted into the new bit frame F''8. Next, the symbol string SSR is outputted to the circuit-switched LAN connection section 3.
The operation from when the symbol string S81 is input to the confluencer 41 until it is temporarily stored in the internal memory is as follows.
Symbol string 5 explained in the first processing procedure described above
Since the operation is the same as that from when sIl is input to the circuit-switched LAN connection unit 34 until the symbol string S67 is input to the convergent unit 36 and temporarily stored in the internal memory, the explanation thereof will be omitted.

Next, in the confluencer 41, when the bit frame F outputted from the shunt 40 is detected and the no data symbol (ND) from the bit frame F is detected, the symbol strings S PT and SST are output from the memory. is extracted and this symbol string SP? and S ST is replaced with a no data symbol (ND). As a result, the symbol string SA is output from the combiner 41. At this time, if there are no symbol strings SPT and SsA in the memory,
Bit frame F°'8 is output as is as symbol string SA.

When the symbol sequence S is input to the encoding unit 42, the symbol sequence SA is encoded into a transmission signal and transmitted via the connector 38 and the transmission line 18.

The operation of the communication station 17t explained above is as follows for each communication station 1
7. and 174 are also performed in the same way, so the explanation thereof will be omitted.

Then, when the bit frame FB encoded and transmitted from the mask station 171 goes around the transmission path 18 and is again input to the mask station 171, the above-mentioned reception processing and transmission processing are performed in the mask station 17 as well. , the bit frame Fa is encoded and transmitted again.

By repeating the operations described above in each of the communication stations 171 to 174, communication of musical tone control data and audio data is performed using one transmission path 18.

Incidentally, the LAN failure recovery operation explained in the first concept described above can also be applied to the ring LAN according to the second concept.

In addition, the LAN according to the first and second processing procedures described above
In the embodiment, an example was shown in which the configuration shown in FIG. 5 was used as the packet-switched LAN connection section 4, but the present invention is not limited to this. In other words, a ring-shaped packet-switched LAN
Any type of material may be used as long as it is used in

Furthermore, LA according to the first and second processing procedures described above
In the embodiment N, each communication station 17 has a packet-switched L
Although an example has been shown in which there is one each of the AN connection section 4 and the line-switched LAN connection section 34, the present invention is not limited to this, and more LAN connection sections may be connected.

In addition, in the embodiment of the LAN according to the first processing procedure described above, an example was shown in which the bit frame F5 has an undefined length and the end of the bit frame Fe is detected by detecting the preamble (PRA). bit frame F
, as a bit string start synchronization symbol (BS) with a fixed length, and then detecting a preset number of bits,
Alternatively, the end of the bit frame FB may be detected. Furthermore, even if the bit frame Fit has an undefined length, by encoding a symbol indicating the end of the bit frame FB, the end of the bit frame F may be detected by detecting this symbol.

Furthermore, in all of the embodiments described above, since the previously proposed packet-switched LAN connection unit is used, an example is shown in which commands and stream data are transmitted through separate LAN connection units, but the present invention is not limited to this. . That is, since it is sufficient that commands and stream data can be transmitted through one LAN, commands and stream data may be transmitted through one LAN connection section.

"Effects of the Invention" As explained above, according to the invention described in claim 1, multiple stream data can be communicated over one LAN with a simple configuration and protocol without reducing communication efficiency. effective.

Further, according to the second aspect of the invention, there is an effect that the speed of the slot and the speed of the stream data can be adjusted. Therefore, stream data can be transmitted in real time.

Furthermore, according to the third aspect of the present invention, each receiving station can know that a communication abnormality has occurred. Therefore, each receiving station can take various measures against this communication abnormality.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a ring-type LAN according to an embodiment to which the first and second concepts are applied, and FIG. 2 shows the configuration of a communication station 17 according to an embodiment to which the first concept is applied. 3 is a block diagram showing the configuration of the communication station 17 according to an embodiment using the first processing procedure of the second concept, and FIG. 4 is a block diagram showing the configuration of the communication station 17 using the second processing procedure of the second concept. FIG. 5 is a block diagram showing the configuration of a slave station 17 according to an embodiment of the present invention.
FIG. 6 is a block diagram showing an example of the structure of a frame and its peripheral devices, FIG. 6 is a diagram showing an example of a frame structure according to the first concept, and FIG. Figure 8 is a diagram showing an example of the configuration of the control unit. Figure 8 is a diagram showing an example of the configuration of the control unit for transmitting and receiving signals in a ring-type LAN to which the second concept is applied. A diagram showing an example of the encoding method, FIG. 10 is a diagram showing an example of the structure of a frame according to the first concept, FIG. 11 is a diagram showing an example of the structure of audio data according to the first concept, and FIG. FIG. 13 is a diagram showing an example of the data encoding method based on the second idea. FIG. 13 is a diagram showing an example of the structure of a bit frame based on the second idea. 1.28.38...Connector, 3.19.29
゜31...Decoding section, 4...Packet switching type LAN connection section, 13, 23, 32, 37.42...
... Encoding section, 15.34 ... Circuit switched LAN connection section, 17, ~174 ... Communication station, 1
Death: Transmission path, 21: Musical tone control data processing section, 22.35: Old: Audio data processing section, 24: Reception control section, 27...・・Transmission control unit, 30, 33, 39.40 ・・・Flow divider,
36.41... Merger.

Claims (3)

[Claims] (1) In a circuit-switched LAN in which a plurality of communication stations are connected in a ring shape through a transmission path and stream data is communicated between these stations, the transmitting station synchronizes the stream data and the stream data. The synchronization data of is encoded into symbols using the same encoding method, and these symbols are divided and inserted into preset slots with the same number of a plurality of frames having a plurality of slots corresponding to a plurality of channels, and the transmission path is The receiving station connects the symbols in the same numbered slots of the plurality of frames transmitted via the transmission path, extracts stream data, and combines this stream data with the synchronized data. A circuit-switched LAN characterized by synchronized output. (2) If the transmitting station does not have the stream data to be transmitted, the transmitting station transmits a symbol indicating that there is no stream data to the corresponding stream data in the frame instead of a symbol encoded with the stream data. 2. The circuit-switched LAN according to claim 1, wherein the circuit-switched LAN is inserted into a slot for transmission. (3) When the transmitting station detects a communication abnormality, the transmitting station inserts a symbol indicating the communication abnormality into the corresponding slot of the frame instead of a symbol obtained by encoding the stream data, and transmits it. A circuit-switched LAN according to claim 1 or claim 2.