JPH0344466B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a communication system in which a plurality of terminal devices are connected to a time division multiplex transmission path and communicate with each other.

<Prior Art> A conventional system of this type was configured as shown in FIG. In other words, the transmitting circuits DRV and receiving circuits RCV of multiple terminals TE ₁ to TE _o are commonly connected to one transmission line BUS, and multiple terminals TE 1 to TE o are connected in common on the transmission line BUS in a time-sharing manner as shown in Fig. 2. information channels I ₁ to _{I n} were arranged. In order for terminals to communicate with this configuration, the transmitting terminal sends information to the transmission path BUS at a timing corresponding to a specific one of the information channels, and the receiving terminal transmits information at the same timing. One-way communication is realized by taking in information from the transmission line BUS.
In order to perform full-duplex communication, it is necessary to use two of the above-mentioned information channels.

There is a method shown in FIG. 3 as a method for increasing the number of terminals accommodated in this type of system. This is a transmission line
A device that connects some of the terminals connected to the BUS ADP ₁ ~
Replace ADP _l with these coupling devices ADP ₁ ~ _{ADP l}
This system connects two similar systems by connecting the transmission lines BUS ₁ and BUS ₂ via the bus. In this case, the coupling device takes in the output information of the transmitting terminal from one transmission line BUS ₁ and transfers it to the other transmission line BUS _2.
Communication between arbitrary terminals is realized by relaying and sending to.

However, such conventional methods had the following drawbacks.

(a) One transmission line by accommodating l coupling devices
The number of terminals that can be accommodated on the BUS is from n to k=n−
decreases to l.

(b) The number of simultaneous communications between systems is limited by the number of coupling devices.

<Summary of the invention> This invention provides a transmission path through which a terminal should send a signal,
The transmission line for receiving the signal is separated from the transmission line, and a communication control device is installed at one end of the line, and when a single system is operating, information from the former is returned to the latter, making it possible to connect multiple systems as necessary. In this case, by connecting the communication control device of each system to an exchange switch, it is possible to expand the system capacity without affecting the number of terminals that can be accommodated per transmission path or the number of simultaneous communications between systems.

FIG. 4 shows an embodiment of the present invention, in which one communication control device CE and a plurality of terminal devices TE ₁ to TE _o are connected to a time division multiplex transmission line BUS. The time division multiplex transmission line BUS is an R line that transmits signals sent from the communication control device CE to each terminal device TE ₁ to TE _o , and a signal sent from each terminal device TE ₁ to _{TE o} to the communication control device CE. It consists of T-wires that transmit data towards
Line driver DRV in communication control equipment CE,
Main transmission control circuit via line receiver RCV
MTRC is connected to the transmission line BUS, main control circuit MC is connected to main transmission control circuit MTRC, and state management section SM is connected to main control circuit MC. The state management unit SM manages the usage state of the information channel on the transmission line BUS.

In each terminal device, as shown in TE ₁ , a terminal transmission control circuit STRC is connected to a transmission line BUS via a line driver DRV and a line receiver RCV, and a terminal transmission control circuit STRC is connected to an input/output circuit SC and a terminal control circuit. Circuit KTC is connected. Address setting means TA for setting its own address is connected to the terminal control circuit KTC. Terminal transmission control circuit
A frame disassembly circuit DMX is connected to the line receiver RCV in the STRC, and the frame disassembly circuit DMX takes out the information specified by the reception channel register IRR from the received information channel and supplies it to the input/output circuit SC. Supply the control channel to the terminal control circuit KTC. The frame assembly circuit MPX sends input information from the input/output circuit SC to the information channel specified by the transmission channel register ITR to the line driver DRV, and sends a control signal from the terminal control circuit KTC to the control channel.

Figure 5 shows the transmission path in the communication system shown in Figure 4.
FIG. 2 is a diagram showing a frame structure of a transmission signal on the BUS, and one frame is composed of m+1 channels. Figure a shows the structure of a transmission signal frame on the R line, where one frame consists of reception information channels IR ₁ to _{IR n} and reception control signal channel DR. Figure b shows the configuration of a transmission signal frame on the T line, and one frame consists of transmission information channels IT ₁ to _{IT n} and a transmission control signal channel DT.

The main transmission control circuit MTRC in Fig. 4 separates (A) information channels IT ₁ to _{IT n} from the signals received from the T line, and outputs them to the output terminal MIT according to the order in which they were received, (B) transmission control signals. Separates the channel DT and outputs it to the output terminal MDT, and (C) returns the information of the information channels IT ₁ to IT _n input from the output terminal MIT to the input terminal MIR to the received information channels IR ₁ to _{IR n} , (D) The control signal inputted from the main control circuit MC via the terminal MDR is placed on the reception control signal channel DR and sent to the R line.

On the other hand, in the terminal device, the terminal transmission control circuit STRC (a) separates information from a specific information channel (one of IR ₁ to IR _n ) from the R line and supplies it to the input/output circuit SC via the output terminal SIR. (b) Separates the information on the control signal channel DR from the R line and supplies it to the terminal control circuit KTC via the output terminal SDR; (c) Specifies the information input from the input/output circuit SC via the terminal SIT. (d) Send information supplied from the _terminal control circuit KTC to the control signal channel _DT .

In (a) and (c) above, the main control circuit determines the information channel to be received or transmitted by each terminal device.
MC and terminal control circuit KTC control signal channel DT
and by communicating with each other via DR. To achieve this, the main control circuit MC periodically polls each terminal control circuit KTC, instructs each terminal control circuit KTC to operate, and receives requests from each terminal control circuit KTC.
The polling signal is composed of address information for identifying each terminal control circuit KTC and data information for instructing control conditions, and each terminal control circuit KTC is activated when the value set by the address setting means TA matches the above address information. , receives the control signal channel DR from the main control circuit MC, and transmits the control signal channel DT to the main control circuit MC.

The operation will be explained by taking as an example the case where the terminal device TE ₁ makes a call and communicates with the terminal device TE _o . terminal device
When polling is performed from the main control circuit MC, the control circuit KTC of TE ₁ transmits call information for the terminal device TE _o to the main control circuit MC through the control signal channel.
Send via DT. The main control circuit MC refers to the information channel status management unit SM, checks the usage status, and searches for an unused information channel. Here, the transmitting information channels IT ₁ and IT ₂ are unused (of course the receiving information channel IR ₁ which is folded back to these
and IR ₂ are also unused). At this time, the main control circuit MC performs the following operations.

() For the terminal control circuit KTC of terminal device TE ₁ ,
IT ₁ is designated as the transmission information channel to be used, and IR ₂ is designated as the reception information channel to be used, respectively, by the control signal channel DR.

() For the terminal control circuit KTC of the terminal device TE _o ,
An incoming call instruction is given, and IT ₂ is designated as the transmission information channel to be used, and IR ₁ is designated as the reception information channel to be used, respectively, by the control signal channel DR.

The terminal control circuit KTC of each terminal is the transmission control circuit
Set the channel number specified by the main control circuit MC in the receive channel register IRR and transmit channel register ITR in STRC. As a result, the frame disassembly circuit DMX extracts the channel information set by the register IRR from the reception information channels IR ₁ to _{IR n} , outputs it to the terminal SIR, and sends it to the frame assembly circuit.
MPX selects terminal SIT for the channel set by register ITR among transmission information channels IT ₁ to _{IT n} .
Send input information from. As a result, the terminal device
The information sent by TE ₁ is transmitted to the terminal device TE _o via the T line channel IT ₁ and the R line channel IR ₁ , and the information sent from the terminal device TE _o is transmitted to the T line channel IT ₂ and the R line channel IR 1. terminal device via channel IR ₂
The signal is transmitted to TE ₁ , and mutual communication between both terminal devices TE ₁ and TE _o is realized.

In this way, communication can be provided between any terminal devices TE ₁ to _{TE o} connected to the transmission path BUS. The above example shows a configuration in which each terminal device selectively uses both transmission and reception information channels, but if the number m of information channels is greater than the number n of terminal devices, the information to be transmitted or received is Even if one of the channels is fixed for each terminal device, the same communication function as described above can be achieved.

FIG. 6 shows another embodiment of the present invention, in which the main device CE includes a plurality of transmission control circuits MTRC ₁ to MTRC.
MTRC _N is provided, and these are connected to time division multiplex transmission lines BUS ₁ to BUS _N via separate line drivers DRV and line receivers RCV, respectively.
The main transmission control circuits MTRC ₁ to MTRC _N are connected to exchange switches SW. The exchange switch SW inputs the information channels received by each main transmission control circuit MTRC ₁ to MTRC _N from terminals MIT ₁ to _{MIT N} ,
Based on the instructions from the main control circuit MC, any information channel of any terminal is connected to terminals MIR ₁ to _{MIR N.}
Output to any channel of any terminal.

Each main transmission control circuit MTRC ₁ to MTRC _N has output terminals MDT ₁ to MDT _N for control signals received from the T line,
Input terminal for control signal to be sent to R line MDR ₁ ~
It is connected to the main control circuit MC via the MDR _N , and the main control circuit MC exchanges control signals with each terminal device in a polling format as in the case of the first embodiment.

The operation will be explained by taking as an example the case where the terminal device TE ₁₁ makes a call and communicates with the terminal device TE _No. When polling is performed from the main control circuit MC, the terminal control circuit KTC of the terminal device TE ₁₁ sends the call information for the terminal device TE _No to the main control circuit MC through the transmission line.
Send via channel DT of BUS ₁ . The main control circuit MC checks the usage status of the information channels of the transmission line BUS ₁ to which the terminal device TE ₁₁ belongs and the transmission line BUS _o to which the terminal device TE _No belongs, using the state management unit SM, and searches for an unused channel.

After this, the main control circuit MC performs the following operations.

() For the terminal control circuit KTC of the terminal device TE ₁₁ ,
The transmission information channel and reception information channel to be used are specified by channel DR of transmission path BUS ₁ .

() For the terminal control circuit KTC of the terminal device TE _No.
The incoming call instruction and the transmission information channel and reception information channel to be used are specified by the channel DR of the transmission path BUS _N.

() Outputs specifications for connecting the transmission information channel of () to the reception information channel of () and the transmission information channel of () to the reception information channel of (), respectively, to the exchange switch SW.

On the other hand, the terminal transmission control circuit STRC is set so that both terminal devices transmit and receive information to and from the information channel specified by the main control circuit MC. As a result, the information sent by the terminal device TE ₁₁ is transmitted through the transmission path.
The information sent from the terminal device TE _No is transmitted via the T line of BUS ₁ , the exchange switch SW, and _the R line of _the transmission line BUS _N. The signal is transmitted to the terminal device TE ₁₁ via the R line of the bus ₁ , and mutual communication between the two terminal devices is realized.

<Effect> As explained above, according to the invention, when the number of information channels on one set of transmission paths is n, when a single system is operating (first embodiment) or when multiple systems are interconnected ( Regardless of the second embodiment), the number of information channels that can be used by the terminal devices connected to each transmission path remains n, and there is no restriction on the number of accommodated terminals due to interconnection. Furthermore, by configuring the exchange switches SW into a complete group, it is possible to create a configuration in which there is no restriction on the number of simultaneous connections between systems.

As described above, the present invention has great flexibility in expanding the equipment scale of a communication system, and greatly contributes to making the equipment more economical.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration of a conventional communication system, Fig. 2 is a diagram showing the frame structure of a signal transmitted through the transmission line BUS in Fig.
FIG. 4 is a block diagram showing the first embodiment of the present invention; FIG. 5 is a diagram showing the frame structure of the transmission signal in FIG. 4; FIG. FIG. 2 is a block diagram showing a second embodiment of the present invention. CE: Communication control equipment, TE ₁ ~ TE _o , TE ₁₁ ~
TE _No : Terminal equipment, BUS: Time division multiplex transmission line, R
Line: 1st track, T line: 2nd track, IR ₁ ~
IR _n : Reception information channel, IT ₁ to _{IT n} : Transmission information channel, STRC: Terminal transmission control circuit as first transmission and reception means, MTRC: Main transmission control circuit as second transmission and reception means, MTRC ₁ to MTRC _N :3rd
Main transmission control circuit as a means of transmitting and receiving.

Claims (1)

[Scope of Claims] 1. A communication system comprising one or more time-division multiplex transmission paths accommodating a communication control device and a plurality of terminal devices, wherein the time-division multiplex transmission path transmits signals sent by the communication control device. a first line for transmitting a signal to each of the terminal devices, and a second line for transmitting a signal sent from each of the terminal devices to the communication control device.
a frame signal transmitted through the first and second lines has a plurality of information channels and one control channel, and the communication control device manages the usage status of the information channel. channel allocation means for allocating arbitrary information channels of the first and second lines to the terminal device by the control channel; a first transmitting/receiving means for relaying information included in the information channel to an information channel on a first line of any of the time division multiplex transmission paths predetermined in correspondence with each of the received information channels; Each of the terminal devices has an information receiving operation using an information channel on a first line specified by the communication control device and an information channel on a second line specified by the communication control device. a second one that performs both or either of the information transmission operations used;
A communication system characterized by having a transmitting/receiving means.