JPH06105991B2 - Button telephone device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention connects a main unit and a plurality of key telephones on one transmission line, and provides a plurality of time-divided signal transfer channels on this transmission line. , Button telephone system for communication. In particular, it relates to efficiently setting a control signal transfer link between a main device and a telephone in a key telephone system.

[Conventional technology]

In recent years, in a communication system such as a key telephone, information for digitizing signal transmission between a main device having a switching function and a telephone connected to the main device and connecting a plurality of telephones to a common line to communicate with each telephone A method of time-division multiplex transmission is considered.

The signals to be transmitted via the transmission line are classified into two types. One is communication information (for example, voice) between telephones, and a channel for transferring this is called a B channel (voice or data information channel). The other is a control signal for monitoring or controlling the operating state of the telephone between the telephone and the main unit, and a channel for transferring this is called a D channel (control channel).

As one of the conventional methods for realizing the multiplex transmission, there is a method in which the same number of B channels and D channels as the number of accommodated telephones are provided on the transmission line and one channel is fixedly assigned to each telephone.

As another conventional method for realizing multiplex transmission,
There is a basic access interface scheduled to be adopted by ISDN (Integrated Services Digital Netwrk). In this method, only one D channel is provided on the transmission path, and a plurality of telephones acquire the right to transmit to the D channel while performing contention control with each other. The signal reception from the D channel is performed by determining the coincidence of the address information. By exchanging control signals over the D channel, many telephones share a limited number of B channels,
Efficient communication can be performed.

[Problems to be solved by the invention]

By the way, the same number of B-channels and D-channels as the number of accommodated telephones are provided on the above transmission path, and each telephone has one
The method of fixedly assigning each channel is a simple method that does not require control regarding channel assignment, but has the following problems.

The usable bandwidth (bit rate) of one telephone is limited to one B channel.

In the case of relatively low traffic, many B channels are left unused and the band on the transmission line cannot be effectively used.

The bit rate of the signal transmitted through the transmission line becomes high.

Also, the basic access interface method, which is scheduled to be adopted in ISDN, can solve the above problems, but the processing required for the telephone and the main device becomes complicated, and it is difficult to realize economically. Is. In addition, at the time of initial setting, a situation in which setting requests from a plurality of terminals are concentrated is likely to occur, and in this case, there is a problem that collision of request signals is likely to occur and processing delay is likely to increase.

The object of the present invention is to eliminate the above-mentioned problems.
It is an object of the present invention to provide a button telephone device in which a telephone can automatically assign a control signal channel that can be used independently, and the line setting process can be simplified.

[Means for solving problems]

According to the present invention, a plurality of telephones are connected to a main device by two sets of time division multiplex transmission lines, the first time division multiplex transmission line transfers information from the main device to the telephone, and a second time division multiplex transmission line. The multiplex transmission line transfers information in the opposite direction, and the transmission frame transmitted by the first time division multiplex transmission line is the common reception time slot commonly used by all telephones and the A plurality of individual reception time slots to be allocated, and an information bit indicating the service provision status of the main unit, and the communication channel setting of the plurality of telephones is a control signal between each of the telephones and the main unit. In the key telephone device controlled by the transmission and reception of each of the telephones, when each of the telephones has the first value, the time slot number designated by the main device by the common reception time slot. Means for receiving, storing and holding, and when the above information bit has a second value, if the above individual receiving time slot number is already held in the own telephone, the individual receiving time slot and individual transmitting time corresponding to this number The control signal is transmitted / received using a slot, and if it is not held, a request signal is sent to the main device in the common transmission time slot and the time slot number is assigned from the main device by the common reception time slot. And means for executing transmission / reception of the control signal using corresponding individual reception and transmission time slots.

[Work]

In the present invention, the transmission frame includes, for all telephones, an information bit indicating the state of call control signal transmission / reception of the main unit, and a plurality of control signal time slots to be individually assigned to each telephone. There is. When the information bit is, for example, "0", each telephone receives the control signal time slot number designated by the main unit for each telephone and stores it in its storage means. When the above information bit is "1", each telephone set transmits / receives the control signal using this control signal time slot if the transmitted control signal time slot number is already held in the own telephone set. To execute. If not received, a request signal is sent to the main device using the assigned control signal time slot, and after the control signal time slot number is assigned from the main device, this control signal time slot Is used to send and receive control signals. Furthermore, the above-mentioned time slot setting is such that multiple basic transmission frames are connected to form a multi-frame, and the first shared slot that is shared by all telephones and the second shared time that should be individually assigned to each telephone. The same is done using slots.

That is, the present invention divides the operation of the key telephone system into two states, that is, an initialization state and an online state, and in the initialization state, the main device executes a unique time slot allocation to each telephone, and online. In the state, the telephone set occupies the time slot to perform signal transfer, and also in the online state, the time slot is assigned. Further, when a multi-frame is used as a transmission frame, a plurality of channels individually allocated to each telephone and one channel shared by all telephones are prepared as D channels, and by exchanging control signals via the D channels, The B channel can be assigned to the phone as needed.

Thus, a relatively small number of B channels can be shared by a large number of telephones to improve the B channel usage efficiency, and the shared D channel can be used to send a command in a broadcast format to reduce the load on the main device. Further, the D channel is fixedly assigned to each telephone, and the processing relating to the transmission / reception of the control signal is simplified.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a key telephone device to which the present invention is applied.

In this embodiment, the main device (ME) 10, the telephone (KT1a) 20,
(KT1b) 30, (KT2a) 40 and (KT2b) 50, the telephones 20 and 30 are connected to the main unit 10 by the bus line BUS1.
Similarly, telephones 30 and 40 are connected to bus line BUS2
Are respectively connected to the main device 10. Each of the bus lines BUS1 and BUS2 is composed of two pairs of transmission lines, one of which is a line for transmitting a signal sent from each telephone to the main device 10, and is hereinafter referred to as a T line. The other pair is a line for transmitting a signal sent from the main device 10 to each telephone, and is hereinafter referred to as an R line.

On the bus line, call signals and control signals are time-division multiplexed and transmitted. That is, for signal transmission on the bus line, a fixed time (for example, 125 μs) is defined as a basic unit, and a plurality of time slots are defined within that time. A plurality of these time slots are prepared for each of a call signal transmission and a control signal transmission, and the communication between the main device and each telephone is realized by appropriately allocating the time slot in each of these for each telephone.

Since the configuration of each telephone in FIG. 1 is the same, the configuration will be described using the telephone 20. The telephone set 20 includes a transmission path control circuit (TRC) 23, a telephone call circuit (SPC) 26, a telephone set control circuit section (KTC) 27, a telephone number holding circuit (TENR) 28,
It includes a control channel holding circuit (DCR) 24 and a call channel number holding circuit (BCR) 25. The transmission control circuit 23 sends a signal to the T line via the line driver (DRV) 21 and receives a signal from the R line via the line driver (RCV) 22. All signals transmitted on the R line are input to the SIN terminal of the transmission control circuit 23. On the other hand, the signal transmission from the line driver 21 is controlled by the output EN of the transmission control circuit 23, and the transmission control circuit 23 outputs the signal only while the output EN is "1".
The output signal from the SOUT terminal is applied to the T line. While the output EN is "0", the output terminal of the line driver 21 is in a high impedance state.

The call circuit (SPC) 26 is composed of a transceiver (HS) 26a and an analog / digital converter (A / D) 26b for voice signals,
The digital input / output terminal of the analog-digital converter 26b is connected to the transmission control circuit path 23 via the audio information line BL.

The telephone control circuit (KTC) 27 is a microprocessor (KT
P) 27a is mainly configured to detect input from various buttons (KEY) 27b such as line selection buttons, function buttons and dial buttons, and to provide various display functions such as line lamps and function lamps. DSP) 27c is controlled. Further, the microprocessor 27a is connected to the transmission control circuit 23 by a control signal line DL, and the main device 10 is connected via this line.
Control signals are transmitted and received to and from. Further, the telephone control circuit unit 27 stores a line data table (LDT) 2 for accumulating which real line the line selection button / line lamp corresponds to.
Includes 7b. The data to be stored in the line data table 27d is transferred from the main device 10 at the stage of system initialization.

The telephone number holding circuit (TENR) 28 is an identification number used by the telephone.
A circuit for setting and holding the TEN, which can be configured using a mechanical contact switch or non-volatile memory. All telephones in the system are given different identification numbers TEN. The information held in the telephone number holding circuit 28 is input to the microprocessor 27a.

The control channel number holding circuit (DCR) 24 is a register for designating the number of the control signal time slot that can be used by the telephone among the time slots multiplexed on the bus line. When the microprocessor 27a sets a predetermined number in the control channel number holding circuit 24, the transmission control circuit 23 takes in this information. As a result, the control signal exchanged by the microprocessor 27a with the transmission control circuit 23 is transmitted on the bus line using the designated time slot.

The call channel number holding circuit (BCR) 25 is a register for designating the number of a call signal time slot that can be used by the telephone among the time slots multiplexed on the bus line. When the microprocessor 27a sets a predetermined number in the call channel number holding circuit 25, the transmission control circuit 23 takes in this information. This allows the call circuit
The call signal exchanged by the transmission control circuit 23 by the 26 is transmitted on the bus line using the designated time slot.

As is clear from the above description, each telephone sets a predetermined time slot from the plurality of control signal time slots and call signal time slots multiplexed on the bus line under the control of the microprocessor in the telephone. It is possible to select and transmit / receive a call signal and a control signal to / from the main device 10.

The main unit (ME) 10 has bus control circuits (BCC1) 14 and (BC
C2) 15, speech path switch (SW) 13, office line trunk (TRK)
1) 11 and (TRK2) 12 and main controller (CC) 16 are included.

Bus control circuits (BCC1) 14 and (BCC2) 15 are bus lines
The bus control circuit 14 is arranged corresponding to each of BUS1 and BUS2. In FIG. 1, the bus control circuit 14 is used for the bus line BUS1 and the bus control circuit 15 is used for the bus line BUS2. The bus control circuits 14 and 15 send and receive the multiplexed call signals to and from the call path switch 13 via the highways HW1 and HW2, respectively, and the control signals via the internal data line DB to the main control unit.
Send and receive to and from 16. In addition, the bus control circuits 14 and 15 receive the call and control signals transmitted and received inside the main unit 10 from the bus line BU.
It is multiplexed on S1 and BUS2 and transmitted / received between telephones 20, 30, 40 and 50. There is a one-to-one correspondence between the time slots for call signals on the bus lines BUS1 and BUS2 and the time slots on the highway.
Is associated with.

The control signal transferred on the inner data lines DB1 and DB2 is configured to include, as address information, the number of the control signal time slot on which the signal is transferred on the bus lines BUS1 and BUS2. When the bus control circuits 14 and 15 receive the control signal from the bus lines BUS1 and BUS2, the bus control circuits 14 and 15 add the time slot number in which the received signal exists to the actual data and transmit the data through the internal data lines DB1 and DB2. To the main control unit 16.
On the contrary, when the control signal is transferred from the main control unit 16 to the bus control circuits 14 and 15, the main control unit 16 adds the time slot number on the bus line BUS1 or BUS2 to be transmitted to the actual data to add the bus control circuit. Notify 14 and 15. The bus control circuits 14 and 15 send the transferred signals to the corresponding time slots.
In this way, the main control unit 16 can specify the telephone set to be controlled and output the control signal.

Station line trunks (TRK1) 11 and (TRK2) 12 are station lines CO1 and CO2
The main control unit 16 is instructed to close the DC loop and send a dial signal to the main control unit 16 and notify the main control unit 16 of the detection result of the incoming signal. Also, the voice signal is converted from analog to digital and exchanged with the communication path switch 13.

The main control unit (CC) 16 is mainly composed of a main processor (MP) 16a, manages system data, and controls the operation of each unit of the system. The system data includes telephone identification signal table (TENT) 16b, control signal time slot management table (DCT) 16c, call signal time slot management table (BCT) 16d, telephone identification number TEN and telephone accommodation position number LEN conversion table (NXT). ) Held at 16e. The telephone identification number table 16b has an identification number TEN as an address and holds the following information.

The operating status of the telephone having the identification number TEN (operating, moving, unregistered).

 Bus line BUS number to which the phone is connected.

The control signal time slot number assigned on the bus line.

Information on the function assignments for the buttons and lamps of the telephone.

Other service-related data (such as speed dial number information).

Table 1 shows a configuration example of the control signal time slot management table (DCT) 16c. The control signal time slot management table 16c is configured by arranging a control word that is configured such that each address has a bus line BUS number as an address and one bit corresponds to each control signal time slot on the bus line. Whether the time slot is used or not is stored as 1 (in use) or 0 (unused) of each bit.
When the transmission frame of FIG. 2 described later is used, the word length of the control word is 23 bits. Table 1 shows an example corresponding to this.

Since the main processor (MP) 16a can send and receive control signals to and from individual telephones, at the system initialization stage,
Assign individual control signal time slots to each telephone. After this control is performed, the set of bus line BUS number and time slot number DCN is 1: 1 with telephone identification number TEN.
Will correspond to. The former set of numbers is called the telephone accommodation position number LEN. Correspondence between these two is the telephone identification number TEN / phone accommodation position number LEN conversion table 16e
Memorized in.

Table 2 shows an example of the structure of the call signal time slot management table (BCT) 16d. The communication time slot management table 16d is configured by using a bus line BUS number as an address, and arranging a control word configured to correspond to each address with 1 bit for each of the control signal time slots on the bus line,
Whether the time slot is used or not is stored as 1 (in use) or 0 (unused) of each bit. When the transmission frame shown in FIG. 2 described later is used, the word length of the control word is 8 bits. Table 2 shows an example corresponding to this.

An example of the frame structure of a signal transmitted on the bus lines BUS1 and BUS2 in FIG. 1 is shown in FIGS. 2 (a) to (c) and Table 3. FIG. 2 (a) shows the frame structure of the R line, where TSBR0 to 7 are time slots for voice signals, T
SDR is a control signal time slot, TSF is a frame signal time slot, TSS is a system control signal time slot, and TSG is a guard bit time slot. The frame repetition period, that is, the time from the beginning to the end of Fig. 2 (a) is 125 µs, and 1
There is 28 bits of information.

Each of the voice signal time slots TSBR0 to TSBR7 is composed of 8-bit voice information (br0 to br7) and is used for transmission of voice PCM code or digital data.

The control signal time slot TSDR consists of 10 bits,
It is used to transmit a telephone control signal from the main unit 10 to each telephone. More specifically, the 10 bits are composed of an 8-bit control word (br0 to br7), a parity bit p of the control word, and a synchronization status indicating bit s.

The guard bit time slot TSG is inserted between valid information time slots, and guard bits (gb
0 to gb5) are transmitted. Originally, this time slot is T
The purpose is to guarantee the timing so that the information transmitted in adjacent time slots on the line does not overlap each other, but it can also be used for the purpose of transmitting additional information from the main device 10 to each telephone. is there.

The system control signal time slot TSS is composed of a DE bit for displaying the operation state of the main control unit 16 in the main device 10 and timing bits (rt0 to rt3) for notifying various timing information. This portion also serves as a guard bit between the call signal time slot TSBR7 and the control signal time slot TSDR.

In the time slot TSF for frame signal, 2 bits of 7 bits
The frame number represented by a base number (f0 to f6) is transmitted. This portion also serves as a guard bit between the control signal time slot TSDR and the call signal time slot TSBR0.

Table 3 shows the multi-frame structure of the R line and the information transmitted by each time slot. A multi-frame consists of 96 consecutive frames. The value (frame number) of the frame signal time slot TSF is "0" in the first frame, and is sequentially stepped thereafter, and is "95" in the last frame. By identifying this frame number, the telephone set can establish frame synchronization and multi-frame synchronization.

BR0 to 7 are audio signal time slots TSBR0 to 7, respectively.
A channel for voice or data information (B channel) transmitted by the above. The most common use of the B channel is to provide a transmission rate of 64 kbps by having the telephone use one time slot in each frame and transmitting an 8-bit code in the same time slot in each frame. In addition, it is possible to use one telephone with a plurality of time slots to provide high-speed transmission of 128 kbps, 192 kbps, and the like.

Since the bit strings gb0 to gb5 transmitted in the guard bit time slot TSG are signals that are ignored by the telephone,
It can be set to any value.

Control signal time slot TSDR is within one multiframe
There are 96, but here, a group of 24 time slots (24 D channels: D
R0 to DR23) are defined and control signals are transmitted by each. The DR0 channel is a special channel used for different purposes from other channels and is called a broadcast channel. That is, the signal transmitted through the DR0 channel is received and processed as a valid signal by all the telephones connected to the bus line. On the other hand, the other channels DR1 to DR23 are individually assigned to the telephones connected to the bus line,
One phone uses one channel exclusively. The other channels are ignored and not propagated on the processor 27 in the phone. The control method when allocating the D channel to the telephone will be described later.

The effective information of each D channel is composed of 4 bytes. Table 4 shows an example of how to use these 4 bytes. A transmission control signal used for error control or the like is arranged in the first byte. A command code for instructing the control content is arranged in the second byte, and parameter data 1 and 2 required for executing the control instructed by the command code are arranged in the third and fourth bytes. For example, the command code represents "display instruction", and the maximum 2 bytes of "display content" in parameter data
Can be expressed.

FIG. 2B shows the T-line frame structure in association with the R-line frame structure. Time slots TSBT0 to 7 (for voice signals) and TSDT (for control signals) where a telephone can send a signal are defined on the T line, and each time slot is used as a pair with the corresponding time slot on the R line. It That is, each telephone transmits a signal on the T line in the same time slot in which it receives the signal on the R line.

The signals sent to the audio signal time slots TSBT0 to 7 are added with sync bits st0 (= “1”) and st1 (= “0”) of 2-bit structure before the audio information 8 bits (bt0 to bt7). It is the configured configuration. On the other hand, control signal time slot TS
The signal sent to DT is the control signal 8 bits (dt0 to dt7)
And the synchronization bit st0, s before the parity bit (1 bit)
This is a configuration with t1 added. An example of transmission waveforms when these signals are transmitted on the T line is shown in FIG. 2 (c). Manchester code is used as the transmission code. Period (t1) when all telephones are not transmitting signals to the T line, T
The potential difference between the lines is zero. When the telephone starts transmitting a signal, the start bit is (+ V, -V, -V, +
V) pattern, followed by valid information. The reception of the T line signal in the bus control circuits 14 and 15 of the main unit 10 is started when the state in which the potential difference between lines is zero is changed to the state in which a significant potential difference exists due to the synchronization bit.

If the line length from the main device 10 to the telephone is limited to a certain value or less, the time from the main device 10 transmitting each time slot to the R line until receiving the corresponding signal from the R line is Limited to a certain value or less. From this, the main device 10 can identify the type of the received signal by regarding the signal received within this time as the signal corresponding to the transmitted time slot.

An example of typical operation of the key telephone system configured by using the main device, telephone and transmission frame described above will be described below.

First, based on the flowchart shown in FIG.
The system initialization operation performed immediately after the power is turned on will be described. When the main power of the main unit 10 is turned on and the main unit 10 is in the operating state, the transmission of the frame shown in Table 3 to the R line is started. At this time, the main processor 16a sets the value of the DE bit to "0" to notify the telephone that it is in the process of controlling the system initialization.

Each telephone receives the above frame, detects a frame number that appears periodically, and establishes synchronization. This makes it possible to grasp which position of the multiframe the signal received at each time point corresponds to. When the synchronization is established, the value of the DE bit is first checked, and when the value is "0", the control from the main unit 10 is waited for (the operation when DE = "1" will be described later).

After securing the time required for each telephone to establish synchronization, the main control unit 16 of the main device 10 refers to the telephone identification number table 16b, and sequentially stores the telephone identification number TEN registered as "there is a corresponding telephone". Take out and send out “TEN INQUIRY” signal via DT0 channel of all bus lines in the system. The "TEN inquiry" signal is configured to include the telephone identification number TEN as parameter data.

Each phone receives this signal and the microprocessor 27a
Determines whether the identification number TEN in the received signal matches the number held in the telephone number holding circuit 28 of the own telephone. If there is a match, the microprocessor 27a sends a "TNEN match" signal to the main unit 10 via the DTO channel.
If they do not match, the phone will not start and will wait for the next signal.

The main control unit 16 of the main device 10 starts an operation for allocating a control channel to the telephone when a “TEN match” is returned from any of the telephones in response to the “TEN inquiry”. First, when a response is returned, the bus line BUS number connected to the telephone is identified, and the control signal time slot management table 16c is searched by that value to find an unused time slot. If there is an unused time slot, a "DCN allocation" signal that has the time slot number DCN and telephone identification number TEN as parameter data is sent out via the DR0 channel.

By receiving this signal, the telephone set which satisfies the above-mentioned telephone set identification number TEN can recognize the D channel that can be used by the own telephone set. The microprocessor 27a causes the control channel number holding circuit 24 to hold the assigned time slot number, activates transmission / reception of the control signal for this time slot, and sends a "DCN confirmation" signal as a response to the above signal through this channel. Send out.

When the synchronization of the D channel on the T line is established, the main control unit
16 sets the corresponding bit "1" on the control signal time slot management table 16c and registers it as a busy state, and also sets the value of the s bit of the D channel on the R line to "1" to establish synchronization. Display status. Further, the main control unit 16 refers to the telephone number table 16b and refers to the address corresponding to the telephone whose time slot number DCN has been assigned to the bus line BUS to which the telephone is connected.
The number and the allocated time slot number DCN are written and stored, and the reference data is registered in the telephone identification number TEN / telephone accommodation position number LEN conversion table 16e.
In addition, the main control unit 16 from the telephone identification number table 16b,
The function allocation information for the buttons and lamps is read out and transferred as the initial setting data to the telephone through the D channel.

The initial setting data is configured to include station line number allocation information for station line button numbers on the telephone and station line number assignment information for station line lamp numbers on the telephone.

The telephone sets the received initial setting data as line data in the line data table 27d, and enters the standby state when the reception is completed. During this period, the telephone set waits for the start of call processing acceptance in the main control unit 16 while always sending a "NOP (uncontrolled)" signal to the T line in order not to lose synchronization.

The control of the time slot number DCN allocation for one telephone is completed by the above series of procedures.

The main control unit 16 continues this control while sequentially incrementing the value of the telephone identification number TEN. Phone identification number table 16
When the above control is completed for all numbers registered as “with telephone” in b, a unique time slot number DCN is given to all telephones in the system. This number is set to a different value between the telephones connected to the same bus line (however, there is a telephone having the same time slot number DCN when the bus lines are different). This means that the combination of the bus line BUS number and the time slot number DCN can be associated with the telephone identification number TEN in a one-to-one correspondence.

If the response from the telephone to the “TEN inquiry” from the main control unit 16 is not detected for a certain period of time or more, the main control unit 16 stops the process related to the telephone identification number TEN,
Start processing for the new telephone identification number TEN. At this time, the telephone that did not respond is ignored as it is not incorporated in the system.

When the above procedure is completed, the main control unit 16 enters the exchange processing service acceptance state, and this is indicated by setting the DE bit of the R line to "1".
And send it to notify all telephones. After that, the main control unit 16 always keeps the DE bit at "1" during the normal operation of the system. On the other hand, in the telephone, the microprocessor 27
When a detects DE = "1" and enables various inputs such as dials, line buttons, function buttons, etc. and detects an input signal by the user's operation, a control signal is sent to the T line by the assigned D channel. Send out. In addition, an instruction from the main control unit 16 is transmitted to the broadcast channel (DRO) and the individual allocation channel (DRO).
Ri, but i = 1 to 23), and performs the operation predetermined by the program.

The operation of the entire system will be described by taking as an example the case where the telephone 20 makes an outgoing call connection to the office line CO1. Here, it is assumed that the telephone signal number TEN of the telephone set 20 is "10" and "1" is assigned as the control signal time slot number DCN.

When the telephone set 20 is in the off-hook state and the station line button (button number 1) corresponding to the station line CO1 is pressed, the microprocessor 27a sends out control signals of "off hook" and "button number 1 pressed" through the DT1 channel.

In the main device 10, the main control unit 16 receives the above signal via the bus control circuit 14. A time slot number is added to the signal supplied from the bus control circuit 14 to the main control unit 16. Based on this and the bus line BUS number, the main control unit 16 converts the telephone identification number TEN and the telephone accommodation position number LEN. Table 16
The e is indexed to determine the telephone identification number TEN of the originating telephone 20.

The main control unit 16 searches the telephone identification number table 16b based on the above values, and determines what the station line number corresponding to button number 1 is.

Based on this result, the main control unit 16 drives the office line trunk 11 and closes the loop circuit for the office line CO1.

The main control unit 16 issues a "station line CO1 in use" signal by the DR0 channels of all bus lines, and issues "station line CO1 self-use" via the DR1 channel of the bus line BUS1 to which the telephone set 20 is connected. Send out.

Of the above, the first signal is "bus CO1 in use"
The signal is received by all phones in the system.
Each telephone determines from the line data table 27d whether or not the button and lamp corresponding to the central office line CO1 are in its own telephone, and if there is a corresponding one, the lamp is steadily turned on. On the other hand, the second signal, "own line CO1 self-use" signal, is received only by the calling telephone set 20. Calling phone 20
In response to this signal, the microprocessor 27a changes the station line lamp corresponding to the station line CO1, which has been set to the steady lighting state, to the blinking display indicating the self-use state.

The main control unit 16 refers to the call signal time slot management table 16d, checks the use state of the call signal time slot on the bus line BUS1 to which the calling telephone 20 is connected, and finds an unused time slot. After this, the "call signal time slot allocation" signal is sent out via the DR1 channel of the bus line BUS1, the corresponding bit in the call signal time slot management table 16d is registered as the use state, and the call path, that is, 13 To connect this time slot for call signal to the trunk line trunk 11.

The "call signal time slot allocation" signal is received only by the calling telephone set 20. Microprocessor
In response to this signal, 27a causes the call channel number holding circuit 25 to hold the designated time slot number for the call signal and sets the call path. As a result, the telephone 20 and the office line CO
This means that the call path has been set between 1 and.

A more detailed description will be given below regarding the above-mentioned operation showing the display control of the office line lamp. It is generally considered that it is uncertain which of the two signals sent by the main control unit 16 is received by the calling telephone 20 first.
As described in, "bus line CO1 in use" from the DR0 channel
If the signals are received first, the lamp control may be executed according to the order of reception, but if this order is reversed, problems will occur. There are two possible ways to solve this. One is a method in which the main control unit 16 sends the above two signals at appropriate time intervals. In this case, the microprocessor 27a unconditionally processes the signals in the order of arrival. The other one is a method of always prioritizing the signal of the dedicated channel regardless of the order of arrival when control signals related to the same station line lamp are received in duplicate from the broadcast channel DR0 and the dedicated channel DR1. . In this case, the main control unit 16 does not need to strictly manage the transmission order of the two signals.

Next, an operation when the telephone set 20 is detached from the bus line BUS1 and moved to another bus line BUS2 and connected while the system is operating will be described.

It is assumed that the telephone set 20 has been given "1" as the time slot number DCN. When the telephone 20 is disconnected from the bus line BUS1, the main device 10 loses the signal reception of the DT1 channel and cannot detect the start bit. The bus control circuit 14 keeps this state a certain number of times (for example, 4
The s bit of the DR1 channel is set to "0" when it continues for more than one time. Further, the corresponding bit on the control signal time slot management table 16c is set to "0", and the unused state of this channel is displayed. Further, by referring to the telephone identification number TEN / phone accommodation position number LEN conversion table 16e, the telephone identification number TEN of the telephone 20 is determined,
The telephone presence / absence information on the telephone identification number table 16b is set to "absent", and the reference data on the telephone identification number TEN / telephone accommodation position number LEN conversion table 16e is deleted.

It is assumed that when the telephone set 20 is connected to the bus line BUS2, four telephone sets are already operating on the bus line BUS2 and are in use from time slot number DCN 1 to 4 (see Table 1). When this telephone set 20 is connected to the bus line BUS2 and starts receiving signals, the DE bit on the R line is "1" because the system is already in operation.
As a result, the telephone set 20 is set at the above system initialization (DE =
It is possible to identify that the state is different from “0”). In this case, the telephone set 20 sends a "time slot number DCN request" signal containing the telephone set identification number TEN as a parameter to the DT0 channel.

When this is received by the main device 10, the main control unit 16 checks the telephone identification number table 16h and confirms that the telephone presence / absence information is not "present". This is to prevent multiple telephones having the same telephone identification number TEN from existing in the system. When the confirmation is obtained, the bus line BUS2 corresponding portion of the control signal time slot management table 16c is referred to search for an unused time slot number DCN. In this case, DCN = 6 is unused and the corresponding bit is "0". Based on this result, the main control unit 16 sends a "time slot number DCN added" signal, and the control proceeds thereafter in the same procedure as in the system initialization. When the series of procedures is completed, DE = “1” has already been set, so that the telephone set 20 is ready to receive service immediately.

In the above process, the service data transferred from the main control unit 16 of the main device 10 at the time of reconnection of the telephone set 20 is read from the same telephone set identification number table 16b, so that even if the connection point is moved, it is the same as the original. It is possible to operate under service conditions. Also, when the telephone is newly connected to the bus line in operation, the same operation as the latter half of the above will cause the telephone to be incorporated into the system during operation,
It becomes possible to operate.

On the other hand, if two telephones are connected to the same bus line at the same time, there is a possibility that the two telephones start to simultaneously send out "time slot number DCN request" signals to the broadcasting D channel. In this case, both signals interfere with each other on the bus route, and the signal received by the main device 10 is a combination of both signals. Here, since the respective telephones are given different telephone identification numbers TEN, the main device 10 cannot receive the original normal signal.

As a result, the telephone cannot acquire the control signal time slot by the "DCN allocation" signal. If such a state continues for a certain period of time or more, the telephone sets a waiting time (for example, [TEN value × [time for 4 frames]) determined based on the value of the telephone identification number TEN, and then performs “DCN” again. Send a "request" signal. In this way, each telephone is assured of signal transmission without interference with the other telephones and can obtain a regular DCN allocation.

Although the number of bus lines connected to the main device 10 is limited to two bus lines BUS1 and BUS2 for simplification of the description above, the telephone set identification number table 16b, the control signal time slot management table 16c, and the call Signal time slot management table 16d, telephone identification number TEN, telephone accommodation position number LE
By expanding the address space of the N conversion table 16e, the same method as described here can be applied to a system accommodating a larger number of bus lines.

Further, the transmission frame configuration method has been described assuming that the frame period is 125 μs, the number of B channels in the frame is 8, and the number of D channels is 1. However, the system of the present invention is applicable to configurations in which these values are changed. Easy to apply. For example,
As shown in FIG. 4, a method is conceivable in which the frame period is set to 250 μs and the amount of information in the channel is doubled while keeping the number of B channels in the frame at 8. By using this method, the guard time between channels can be calculated as shown in Fig. 2 (c).
It can be increased compared to t1. As a result, the time margin for overlapping signals between channels is increased, and the line length to the telephone can be increased.

〔The invention's effect〕

As described above, according to the present invention, at the time of initial setting of the key telephone system, the common D channel from the main unit to the telephone is used to issue a simultaneous command, thereby reducing the frequency of signal transmission from the main unit processor to the telephone. Therefore, it is possible to reduce the processing load of the main device processor and prevent an increase in processing delay. Further, in the online state, it is possible to request the allocation of the time slot for the own device from the telephone side, receive the allocation, and transmit / receive the control signal.

In addition, by assigning unique telephone numbers to all telephones in the system and using the common D channel at the start of operation of the telephones, the individual D channels are fixedly assigned to each telephone, thereby processing the main device and the telephones. The load can be reduced.

As described above, according to the present invention, in the key telephone device, the control signal transfer channel can be automatically and efficiently assigned between the device and the telephone, so that the key telephone system is economically constructed. be able to.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a key telephone device to which the present invention is applied. 2 (a) and 2 (b) are explanatory views showing an embodiment of a transmission frame structure. FIG. 2C is a waveform diagram showing an example of the signal. FIG. 3 is a flow chart for explaining the operation of FIG. FIG. 4 is an explanatory view showing another embodiment of the transmission frame structure. 10 …… Main unit (ME), 11 …… Main line trunk (TRK1), 12
...... Station line trunk (TRK2), 13 ...... Call path switch (S
W), 14 ... Bus control circuit (BCC1), 15 ... Bus control circuit (BCC2), 16 ... Main control unit (CC), 16a ... Main processor (MP), 16b ... Telephone identification number table ( TEN
T), 16c ... control signal time slot management table (DCT), 16d ... call signal time slot management table (BCT), 16e ... telephone identification number TEN, telephone accommodation position number LEN conversion table (NXT), 20 …… Telephone (KT1
a), 21 ... Line driver (DRV), 22 ... Line receiver (RCV), 23 ... Transmission control circuit (TRC), 24 ... Control channel number holding circuit (DCR), 25 ... Call channel number holding Circuit (BCR), 26 …… Call circuit (SPC), 26a ……
Handset (HS), 26b ... Analog / digital converter (A / D), 27 ... Telephone control circuit (KTC), 27a ... Microprocessor (KTP), 27b ... Various buttons (KE
Y), 27c ... Display circuit (DSP), 27d ... Line data table (LDT), 28 ... Telephone number holding circuit (TENR), 30
...... Telephone (KT1b), 40 ... Telephone (KT2a), 50 ... Telephone (KT2b), BL ... Voice information line, BUS1, BUS2 ... Bus line, CO1, CO2 ... Station line, DB1, DB2 ... … Internal data lines,
DL: control signal line, EN: output, HW1, HW2: highway, SIN, SOUT: terminals.

Continuation of front page (56) References JP-A-56-8984 (JP, A) JP-A-59-5796 (JP, A) JP-A-61-67389 (JP, A)

Claims (1)

[Claims] 1. A plurality of telephones are connected to a main unit by two sets of time division multiplex transmission lines, a first time division multiplex transmission line transfers information from the main unit to the telephone set, and a second time division multiplex transmission line. The division multiplexing transmission line transfers information in the opposite direction, and the transmission frame transmitted by the first time division multiplexing transmission line is the common reception time slot (DR0) commonly used by all telephones and A plurality of individual reception time slots (DR1 to DR23) that should be individually allocated to
A key telephone including an information bit (DE) indicating a service provision state of the main device, wherein communication channel settings of the plurality of telephones are controlled by transmission and reception of control signals between the respective telephones and the main device. In the device, each of the telephones receives a time slot number designated by the main device by the common reception time slot when the information bit has a first value, and stores and holds the time slot number. When the value is set, if the individual reception time slot number is already held in the own telephone, the control signal is transmitted and received using the individual reception time slot and the individual transmission time slot corresponding to this number, and it is held. If not, a request signal is sent to the main device in the common transmission time slot, and the main device transmits the request signal in the common reception time slot. Key telephone system characterized in that it comprises means for performing transmission and reception of the control signal using the corresponding individual receive and transmit time slots after receiving the assignment of the time slot number.