JPH0530341B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an electronic exchange that communicates or exchanges various data between data terminals.
More specifically, the present invention relates to an improvement in a circuit portion that matches the operating state of a data terminal with the operating state of the data terminal recognized by the electronic exchange.

[Technical background of the invention]

Conventionally, in this type of electronic exchange, the communication line between data terminals is formed by an electronic exchange, but within the electronic exchange, the operating state of the data terminal is recognized based on a state transition diagram, and this recognition Depending on the results, line switching and connection processing is performed.

By the way, such state recognition consistency needs to be maintained normally even when the data terminal is in transition, that is, when the data terminal is powered on and off, and when the electronic exchange is powered on and off.

Conventionally, therefore, a method has been adopted in which such status recognition is performed by sending a status inquiry signal from the electronic exchange side.

Figure 1 shows the system configuration of an electronic exchange that exchanges data. 1 is an electronic exchange, 2 is a data terminal, 3 is a data service unit, 4 is a line, and 5 is a data terminal.
is a data communication interface, 6 is a communication path switch, 7 is a signal transmission/reception circuit, 8 is a communication path drive circuit,
9 is a central processing circuit, 10 is a main memory, 11 is a data bus, 12 is a signal bus, and 13 is a time division multiplex communication path.

In such a configuration, the central processing circuit 9
The exchange process is executed according to the conversion process program stored in the main memory 10. At this time, reading of the program, reading of the terminal status, writing of a new status after the exchange process, etc. are performed via the data bus 11.

The signal transmitting/receiving circuit 7 sends command data transmitted from the central processing circuit 9 to the data communication interface 5 and request data from the data service unit 3 received by the communication interface 5 to the central processing circuit 9.

The data communication interface 5 is the data terminal 2
The communication data sent from the data service unit 3 is separated from the service request data sent from the data service unit 3, and the former communication data is sent to the time division multiplex communication path 1.
3, and the latter request data is sent to the signal bus 12. Furthermore, the communication data sent from the communication path switch 6, which is completely opposite to the above-mentioned operation,
It combines the command data sent from the signal transmitting/receiving circuit 7 and transmits it to the line 4. In this case, data transmission and reception with the line 4 is performed according to, for example, a dedicated protocol.

On the other hand, the data service unit 3 receives a service request from the data terminal 2, converts it into a request signal that can be interpreted by the electronic exchange 1, and sends it to the line 4, or converts the command data sent from the data communication interface 5 into a request signal that can be deciphered by the electronic exchange 1. and gives appropriate instructions to the data terminal 2. Additionally, communication data is transmitted transparently.

The transmission method for the line 4 is, for example, a ping-pong transmission method that allows full-duplex communication of digital signals over two wires, and an example of its data format is shown in FIG.

In FIG. 2, 14 is a synchronization signal, and 15 is a communication data portion, the data length of which is usually 8 bits. Reference numeral 16 denotes a control signal, and the above-mentioned command data or request data is transmitted, for example, one bit at a time in a multi-frame format. 17 is a parity for error control. In this case, each bit is transmitted in the order starting with the synchronization signal 14.

In such a system, the data terminal 2
The state is recognized by the electronic exchange 1 through the terminal monitoring operation shown in the flowchart of FIG. That is, FIG. 3 is a flowchart showing the contents of the terminal monitoring program executed by the central processing circuit 9. In the figure, 18 indicates that the data terminal 2 is powered on and is operating normally; 19
20 is a state in which the data terminal 2 is in normal operation and is inquiring about its status and is waiting for a response; 20 is a state in which the data terminal 2 is not operating due to the power being cut off or a line abnormality, etc. It represents the state of no. Further, 21 indicates that a status inquiry signal has been sent, 22 indicates that a response signal has been received, and 23 indicates that no response signal has been received even after a certain period of time has elapsed.

The terminal monitoring program sends an inquiry signal to the data terminal 2 and waits for a response from the terminal 2. As a result, if the response signal is received within a certain period of time, the terminal 2 is determined to be normal and the conversion processing for this terminal is continued. However, if no response is received within a certain period of time, it is assumed that the operation of the terminal 2 has stopped, and no exchange connection will be made thereafter.

However, in order to know that the operation of the terminal has recovered in this state, an inquiry signal is sent out at regular intervals and the response is monitored.

Through such operations, the operating state of the data terminal 2 is recognized.

[Problems with background technology]

However, since the above device relies only on the status inquiry operation of the electronic exchange to recognize the status of the data terminal, frequent status inquiries must be made in order to further improve the accuracy of the status recognition of the data terminal. The load on the electronic exchange becomes heavy and, for example, if the power to a data terminal is turned off during the exchange connection process and then turned on again within a short period of time, it cannot cope with such state changes and the data terminal remains in an idle state. Despite this, there was a problem in that the electronic exchange still recognized that the communication was in progress.

[Purpose of the invention]

The object of the present invention is to eliminate the above-mentioned drawbacks and provide a data communication device that can reliably recognize changes in the state of a data terminal.

[Summary of the invention]

The present invention provides a data service unit that is interposed between a data terminal and an electronic exchange, and when the power of the data terminal and the data service unit is turned on, an initialization request signal for the state of the data line between the data terminal and the electronic exchange is sent to the electronic exchange. The above purpose is achieved by providing a processing circuit for transmitting data to the data terminal, and configuring the electronic exchange to receive this initialization request signal and initialize the state of the line between the corresponding data terminal and data service unit. ing.

[Embodiments of the invention]

FIG. 4 is a block diagram showing an embodiment of the data service unit which is the main part of the present invention.

In the figure, 1 is an electronic exchange, 2 is a data terminal, and 3 is a data service unit. Of these, the data service unit 3 is a terminal-side interface 24 that sends and receives signals to and from the data terminal 2.
and an exchange side interface 25 for transmitting and receiving signals to and from the exchange 1. Furthermore, the transmission data from the data terminal 2 received from the terminal side interface 24 is converted into a data format at a speed suitable for burst transmission and transferred to the exchange side interface 25, and conversely, the data transmitted from the data terminal 2 is transferred to the exchange side interface 25. Transmission data received from another data terminal in burst transmission format is converted to the speed and data format of the receiving terminal, and sent to the terminal side interface 24, and further transmitted from the converter 1 as shown in FIG. The control signal bits transmitted in the same format are accumulated and sent to the processing circuit 27, and the control signals are received from the processing circuit 27 and sent to the exchange 1 by burst transmission one bit at a time as shown in FIG. is inserted into the signal, and when the transmission is completed, the processing circuit 27
It has a data transmitting/receiving circuit 26 that notifies the navel.

It also has a processing circuit 27, which is composed of a microprocessor and a memory, and communicates various signals and information between the data terminal 2 and the exchange 1 according to a state transition diagram.

In such a configuration, when there is a call request from the data terminal 2, the processing circuit 27 detects this through the signal line 29, and changes the recognition information in the internal memory from the idle state to the call (ready-to-dial) state. At the same time as the transition, a control signal representing a "call request" is sent to the data transmitting/receiving circuit 26. A control signal representing this call request is transmitted to the exchange 1 via the exchange side interface 25. Then, in the exchange 1, the control signal of the call request received at this time causes the state recognition information of the line 4 stored in the internal memory to transition from the idle state information to the call state information, and at the same time indicates "dialable". A control signal is sent back to the data service unit 3.

Then, upon receiving this dialable control signal, the processing circuit 27 in the data service unit 3 changes the state recognition information of the dialable waiting state stored in its internal memory to the information of the dial receiving state, and at the same time, An instruction is given to the data terminal 2 via the signal line 29 to give permission for dial transmission.

In this way, preparations for data exchange are sequentially executed while performing state transitions, and when predetermined conditions are met, a communication line with the receiving data terminal is formed, and via this line, communication with the transmitting data terminal is performed. Data exchange or communication takes place with the receiving data terminal.

By the way, the processing circuit 27 not only changes its state in response to a processing request from the data terminal 2 or the exchange 1 and sends and receives necessary control signals, but also when the data service unit 3 is powered on or when the data terminal 2 is turned on. At the system initialization of the data service unit when the power is turned on,
Furthermore, when an abnormal operation is discovered and a system initialization is performed, an initialization request signal is transmitted to the exchange 1 via the data transmitting/receiving circuit 26. Then, the exchange 1 recognizes that the state of the line 4 between the data service unit 3 that sent this initialization request signal and the data terminal has returned to its initial state.

FIG. 5 is a flowchart showing the state transition when the terminal monitoring program in the exchange 1 receives the initialization request signal. In the same figure, 1
The parts indicated by 8 to 23 show operations similar to the conventional one, but here a process 30 for responding to reception of an initialization request signal is newly added to the parts in states "0" to "2". Therefore, when the central processing circuit 9 (see FIG. 1) in the exchange 1 receives the initialization request signal from the data service unit 3, it recognizes that the line 4 has returned to the normal state, or the data terminal 2 side It is recognized that the line has failed or the power has been restored and the line is now in a state where normal communication is possible. At this time, if the status of the data terminal 2 is recognized as being in communication with the other data terminal, the communication line with the other data terminal is disconnected and the line status is returned to the initial state.

Therefore, in such a configuration, even if the power to the data terminal 2 or the data service unit 3 is cut off and restored instantaneously, when the power is restored, the data service unit 3 issues an initialization request signal and the exchange The state recognition within switch 1 immediately transitions to the initial state, and switch 1
This eliminates the need for frequent status inquiries, and reduces the amount of processing required.
As a result, it becomes possible to reliably recognize a change in the state of the data terminal 2 or data service unit 3 when the data terminal 2 or the data service unit 3 recovers from power-off, and to respond optimally to this change in state.

In addition, in the above, when the line initialization request signal is sent from the data service unit 3 side, the exchange 1
Although the operation on the side has been described, there are cases where the exchange 1 transmits an initialization request signal to the data terminal 2. When the terminal initialization request signal sent from the exchange 1 is received by the data service unit 3, a disconnection instruction signal is sent from the processing circuit 27 to the data terminal 2 if communication is in progress. As a result, when the data terminal 2 becomes ready, the data service unit 3 returns a terminal ready signal to the exchange 1, and the exchange 1 receives this and thereafter performs normal connection processing operations. In this case, if the data service unit 3 is not in communication but in an idle state, it is possible to immediately return the terminal ready signal.

Here, the case where the line initialization request signal is transmitted from the exchange 1 is a case where a temporary failure occurs in the exchange 1 and the exchange 1 is restarted.

By doing this, it is possible to eliminate inconsistencies in line status recognition due to malfunctions on the exchange side, and furthermore, it is possible to know on the terminal side that the cause of the communication abnormality is on the exchange side.

〔Effect of the invention〕

As explained above, the present invention allows a data service unit interposed between a data terminal and an electronic exchange to request initialization of the data line state between the data terminal and the electronic exchange when the data terminal and the data service unit are powered on. A processing circuit is provided to send the signal to the electronic exchange side, and the electronic exchange is configured to receive this initialization request signal and initialize the line status between the corresponding data terminal and data service unit. Changes in the status on the data terminal side can be reliably recognized without frequent status inquiries from the data terminal. Further, it has the effect of reducing the burden on the terminal monitoring function on the exchange side. Furthermore, if the configuration is such that the exchange side sends an initialization request signal to the terminal side, it is possible to eliminate inconsistencies in line status recognition due to malfunctions on the exchange side. This has the effect of letting you know on the terminal side what has happened.

[Brief explanation of drawings]

Fig. 1 is a system configuration diagram of an electronic exchange that exchanges data, Fig. 2 is a diagram showing a data transmission format, Fig. 3 is a flowchart showing a conventional terminal monitoring operation, and Fig. 4 is a main part of the present invention. FIG. 5 is a block diagram showing an embodiment of a data service unit, and is a flowchart showing the terminal monitoring operation in the present invention. DESCRIPTION OF SYMBOLS 1...electronic exchange, 2...data terminal, 3...data service unit, 4...line, 5...data communication interface, 9...central processing circuit, 24...terminal side interface, 25...exchange side interface, 26...data Transmission/reception circuit, 27...processing circuit.

Claims (1)

[Scope of Claims] 1. A data terminal that inputs and outputs communication data, a switch that forms a digital communication line between the data terminals, and a switch that transmits information corresponding to a service request from the data terminal to the switch. , a data service unit that receives data terminal control information from the exchange and controls the data terminal; the data service unit detects the data terminal in the data service unit and power-on of the data service unit; A circuit is provided for transmitting an initialization request signal for the state of the digital communication line with the data service unit and the data terminal, and the switching equipment transmits the state of the digital communication line with the data service unit and data terminal that sent the initialization request signal. An electronic switchboard configured to initialize. 2. A data terminal that inputs and outputs communication data, and an exchange that forms a communication line between the data terminals,
A data service unit that transmits information corresponding to a service request from the data terminal to the exchange and receives data terminal control information from the exchange to control the data terminal, wherein A circuit is provided for detecting the start of operation of the exchange and transmitting a request signal for initializing the state of the communication line with the exchange to the data service unit, and the data service unit receiving the initialization request signal from the circuit 2. The electronic exchange according to claim 1, wherein the electronic exchange is configured to initialize the state of a communication line with a data terminal.