JPH04222150A - Network controller - Google Patents

Abstract

PURPOSE:To compose a network controller 1 by providing a line switching part 2, line coupling part 4, line current detection part 6 and timer part 7. CONSTITUTION:When a line holding state occurs because of a fault or malfunction in the network controller 1 and the generation of line error in a communication line or the like, the timer part 7 counts this line holding time while responding to the detecting output of the line current detection part 6. When the above-mentioned counted time reaches a prescribed time period, the line switching part 2 and the line coupling part 4 are operated to release the holding state of the above-mentioned line. Thus, the above-mentioned communication line can be presented for another communication operation and the availability thereof is improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network control device, and more particularly to a network control device that controls the connection between a communication line connected to one side and a data terminal device connected to the other side.

0002

[Prior Art] Traditionally, existing telephone lines have been used to
To read the measured values of a gas meter, water meter, electric power meter, etc. installed in a telephone user's house without ringing the telephone bell in the house. This is a type of data communication system in the no-ringing communication service and is provided as a telemeter system. As a result, the center side of a gas company or water company can automatically collect desired data when necessary, thereby solving the problem of manpower shortage in data meter reading. FIG. 2 is a schematic block diagram showing the configuration of a data communication system to which a conventional network control device and an embodiment of the present invention are applied.

In the data communication system shown in FIG. 2, a center device 27 includes a host computer 10 and a center-side network control unit (C-NCU) 11. The center-side network control device 11 is connected to the host computer 10 via a connection line 19 and to the center-side telephone exchange 12 via a telephone line 20. On the other hand, the terminal device 26 includes a terminal network control unit (T-NCU) 15,
It includes a meter 16, a terminal such as a sensor 17, and a home telephone 18. The network control device 15 of the terminal is connected to the terminal-side telephone exchange 13 via a subscriber telephone line 22. Further, each terminal from the meter 16 to the home telephone 18 is connected to the network control device 15 of the terminal via a connection line 23. The center-side telephone exchange 12 and the terminal-side telephone exchange 13 are connected to each other by an inter-office trunk line 21.

[0004] In the no-ringing communication system, the network control device 1 on the center side is
1 calls the no-ringing trunk 14 and holds it. Next, after the no-ringing trunk 14 reverses the polarity of the subscriber telephone line 22, it provides a no-ringing paging signal to the network controller 15 of the terminal. When the network control device 15 of the terminal detects a no-ringing call signal, the network control device 15 of the terminal
For example, meter 16, sensor 1 without ringing bell 8.
control so that communication is carried out with 7.

On the other hand, when the terminal makes an automatic call, when the network control device 15 of the terminal detects that a predetermined time has come, the network control device 15 of the terminal automatically calls the network control device 11 of the center side. It will be done. In this case, the meter 16,
Meter reading information from the sensor 17 is transmitted to the host computer 10 via the network control device 15 of the terminal, the telephone line 22, the interoffice trunk line 21, the telephone line 20, and the network control device 11 on the center side. The host computer 10 performs data processing such as charge calculation and printout based on the received information based on predetermined program processing.

[0006] In the above-mentioned telemeter system employing the no-ringing communication method, there are a home telephone 18 as a data terminal device, a meter 16 for meter reading, and a sensor 17 in the consumer's home. Switching of the connection between the telephone line 22 and the data terminal device is controlled by the network control device 15 of the terminal. The network control device 15 of the terminal employed in this telemeter system usually connects the telephone line 2.
2 to connect the in-home telephone 18 to the home telephone 18.

When operating as a telemeter system,
The network control device 15 switches the connection of the telephone line 22 from the home telephone 18 side to the meter 16 or sensor 17 side. That is, the network control device 15 detects the idle state of the home telephone 18 by inputting an on-hook signal from the telephone 18, and
Accordingly, the connection of the telephone line 22 is switched from the in-home telephone 18 side to the meter 16 or sensor 17 side. After that, according to a predetermined transmission control procedure, the terminal makes a call, etc., and the center device 2
7 side and a telephone line are established, and meter reading data from the meter 16 or sensor 17 is sent to the telephone line 22 and transmitted to the center device 27 side.

Furthermore, when collecting meter reading data from the meter 16 or sensor 17 from the center device 27 side, the host computer 10 instructs the network control device 15 of the terminal via the network control device 11 to switch the connection of the telephone line 22. Then, the meter reading data from the meter 16 or sensor 17 side is controlled to be transmitted.

As described above, the conventional network control device 15
It operates to detect the idle state of a connected communication line, switch the connection of the line, and send data from a desired data terminal device to the connected line.

0010

As described above, the network control device controls connection switching between the communication line connected to one side and the data terminal device connected to the other side. Therefore, if a malfunction occurs for some reason on the network control equipment or data terminal equipment side, the specific data terminal equipment will suspend the connection state of the communication line for an unnecessarily long time, and other data terminal equipment will However, the communication request is made to wait until the pending state is released. Therefore, even if an emergency event occurs in another data terminal device, this data terminal device will not be able to shift to a communication state, so there is a risk that the emergency event will bring the system itself into an unrecoverable state. It was a problem.

[0011] Furthermore, there is a problem in that the above-mentioned unnecessarily reserved state of the line reduces the efficiency of using the line and further reduces the data processing capacity of the system itself.

Therefore, an object of the present invention is to prevent communication lines from being held unnecessarily by the data terminal devices in a network control device that connects data terminal devices, thereby increasing the efficiency of using the communication lines. The object of the present invention is to provide a network control device that can implement the system.

[0013]

[Means for Solving the Problems] A network control device according to the present invention is a network control device that connects a communication line and a plurality of data terminal devices, and which responds to a communication start request from each of the plurality of data terminal devices. a line coupling means for coupling the communication line to the network control device; a timekeeping means for counting the holding time of the line by the line coupling means; and a time period measured by the time measurement means reaching a predetermined time period. and a line release means for releasing the line from the held state.

[0014]

[Operation] Since the network control device according to the present invention is configured as described above, when a communication line is to be held for longer than a predetermined communication time, the communication line is disconnected from the network control device, and the communication line is disconnected from the network control device. It acts to set the communication line free and make it available for other communication operations. In other words, the timing means measures the holding time of the communication line by the line coupling means,
When the hold time reaches a predetermined time period, the line release means operates to release the communication line from the hold state.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

The network control device according to one embodiment of the present invention is exemplified as a network control device installed in each home of a telemeter system using an existing telephone line as a communication line, but the scope of application is not limited thereto. In other words, the present invention is applicable to any network control device that has a function of connecting a communication line to one side, connecting a data terminal device to the other side, and controlling connection switching so that these data terminal devices are connected to the communication line.

FIG. 1 is a schematic diagram showing the circuit configuration of a network control device according to an embodiment of the present invention.

As shown in the figure, the network control device 1 connects a telephone line as a communication line, and further connects a meter device (not shown) through a telephone and a meter terminal provided in the house as a data terminal device. .

The network control device 1 includes a line switching unit 2, a control unit 3, a line coupling unit 4, and a line switching unit 2, a control unit 3, a line coupling unit 4, and a line switching unit 2, in order to selectively connect either the telephone set or the meter device to the telephone line to establish a communication state. It includes a modem section 5, a line current detection section 6, a timer section 7, an interface section 8, and a power supply section 9.

The inside of the network control device 1 is composed of a circuit section directly connected to the telephone line, and a low voltage electronic circuit section that should be separated from the circuit section in terms of direct current. A photocoupler is used to isolate the circuit portion during signal transmission.

[0021]Here, prior to explaining the configuration of each circuit within the network control device 1, the photocoupler will be explained.

[0022] A photocoupler is an element that combines a light emitting diode and a phototransistor, and causes the light emitting diode to emit light in response to a signal applied from the outside, and receives the emitted light on the phototransistor side and adjusts it according to the level of light reception. Converts to electrical signal and outputs. In this way, photocouplers transmit signals using light in an insulated space, so they have very good insulation, and can be used to transmit signals to telephone lines.
Conversely, it is possible to effectively prevent transmission signals to be received from the telephone line from interfering with control signals within the network control device 1.

Note that inside this network control device 1,
Two photocouplers are provided, and for each photocoupler, the light emitting diode side is connected to the photocouplers PD1 and PD.
2. The phototransistor side is called photocouplers PT1 and PT2 to distinguish them.

Next, each circuit inside the network control device 1 shown in FIG. 1 will be explained. The line switching unit 2 includes a switch RY1 which is selectively connected to one of the signal input/output terminals S1 and r1, and a switch RY1 which is selectively connected to one of the signal input/output terminals S2 and r2. The switch RY2 includes a switch RY2. The switches RY1 and RY2 are normally in a reset state where they are connected to the terminals r1 and r2, and at this time the line switching unit 2 acts to connect the telephone line to the telephone set. Conversely, when the switches RY1 and RY2 are in the set state connected to the terminals S1 and S2, the line switching section 2 acts to connect the telephone line to the meter device side. The details of the connection switching control operation of the switches RY1 and RY2 will be described later.

The interface section 8 connects the control section 3 to a meter device connected via a meter terminal.

The control unit 3 has a function similar to a simple microcomputer, and operates to send measured value data from the meter device provided via the meter terminal and the interface unit 8 to the telephone line. .

The line current detection section 6 is a photocoupler PD having a light emitting diode, which is the light emitting side of the photocoupler.
Contains 1. The light-emitting diode of the photocoupler PD1 operates to emit light using power supplied from the telephone line when the line switching section 2 is in the set state, that is, when the meter device side is connected to the telephone line. Therefore, while the photocoupler PD1 is emitting light, the line current detection section 6 is in a state of detecting the power supplied from the telephone line.

The line coupling section 4 operates to disconnect and couple the telephone line and the electronic circuit section inside the network control device 1 in a direct current manner. For this purpose, it is configured to include a diode bridge circuit DB1, a photocoupler PT2 including a phototransistor, transistors Q1 and Q2, a resistor R7, and a transformer T. The diode bridge circuit DB1 operates to rectify a current signal input from the telephone line side and provide it to the next stage circuit, and the transformer T inductively couples the telephone line and the electronic circuit inside the network control device 1. and act to block it. therefore,
The photocoupler PT2 including a phototransistor receives light emitted by a photocoupler PD2 including a photodiode, which will be described later, and accordingly the transistors Q1 and Q
2 conducts, the telephone line connects transformer T and resistor R7
terminated by

The modem section 5 includes a processing circuit for modulating and demodulating signals, and after demodulating the signal given from the telephone line, sends it to the control section 3 at the next stage, and vice versa. It modulates the signal given from the terminal so that it can be sent to the telephone line via the line coupling section 4 at the next stage.

The timer section 7 has a resistor R so as to time a predetermined time period during which the network control device 1 can hold the telephone line.
19 and R20 and a capacitor C3, and further includes an operational amplifier OP, a resistor R21, and a resistor R22. The integrated value of the resistors R19 and R20 of the timer section 7 and the respective resistance and capacitance values of the capacitor C3 is calculated by the network control device 1.
is preset to be longer than the normal communication time period for communicating via a telephone line.

In the operational amplifier OP, a power supply voltage is applied to an inverting input terminal via resistors R21 and R22, and a voltage from resistors R19 and R20 and a capacitor C3 is applied to a non-inverting input terminal. When the voltage level applied to the non-inverting input terminal of the operational amplifier OP becomes higher than the voltage level applied to the inverting input terminal, its output becomes active, and this state causes the next stage transistor Q5 to conduct. act. As a result, a current path is established between the power supply section 9 and the transistor Q5, and electromagnetic force is induced in the coil L (R), so that the switches RY1 and RY2 of the line switching section 2 are switched from the set side to the reset side. It is switched and connected to. In other words, switch RY1
When RY2 is in the set state, current detection section 6 is activated and current flows through photocoupler PD1. Accordingly, the capacitor C3 is gradually charged by the voltage from the power supply unit 9 via the photocoupler PT1, and finally reaches a voltage level that activates the output side of the next stage operational amplifier OP. At this time, the network control device 1
Since the communication could not be completed within the set value of the CR timer, that is, within the predetermined communication time, electromagnetic force is induced in the coil L(R), and the telephone line connection is forcibly disconnected. In this manner, the timer unit 7 operates to time the predetermined holding time period of the telephone line by the network control device 1.

The power supply section 9 includes a power supply BT, and supplies the control section 3 and timer section 7 with low voltage power necessary for their operation. In detail, the power supply section 9 includes a photocoupler PD2 including a diode, transistors Q3 and Q
4, and electrically connected to the control unit 3 via the coil L(S), and electrically connected to the timer unit 7 via the photocoupler PT1 including a phototransistor, the transistor Q5, and the coil L(R). is used to supply power. Note that the conduction of the transistor Q5 is caused by the diode D1.
It is controlled by a control signal from the control section 3 via the control section 3 and an output signal from the operational amplifier OP in the previous stage.

[0033] Here, the switching control operation of the connection states of the switches RY1 and RY2 in the line switching section 2 will be explained.

The switches RY1 and RY2 operate in the same manner as self-holding type relay switches, and are connected to the terminals S1 and S2 by the electromagnetic force induced in the coil L(S). ) The connection is switched to the terminals r1 and r2 by the electromagnetic force induced in the terminals r1 and r2. The coil L(S) is made conductive when a predetermined voltage is applied in a pulse form to the gate of the transistor Q3 by the control unit 3 via the capacitor C4, thereby inducing an electromagnetic force. This electromagnetic force is applied to switches RY1 and RY
2 to the terminals S1 and S2. Then, due to the discharge of capacitor C4, transistor Q
3 is again cut off, but switches RY1 and RY
2 maintains the set state by self-holding. Further, the coil L(R) induces an electromagnetic force when the transistor Q5 is turned on by applying a predetermined voltage to its gate side. This electromagnetic force causes switches RY1 and RY2 to connect to terminal r.
1 and r2 side. The transistor Q5 is rendered conductive by the voltage applied to the gate side of the control section 3 via the diode D1, and is rendered conductive by the output signal of the operational amplifier OP of the timer section 7. Therefore, the transition of the line switching section 2 from the reset state to the set state is controlled by the control section 3, and the transition from the set state to the reset state is controlled by a control signal from the control section 3 and a predetermined communication time measurement of the timer section 7. It is controlled by the change in the output signal of the operational amplifier OP in response to termination.

As described above, the network control device 1 includes the line current detection section 6, and further includes the timer section 7 for timing the predetermined communication period in response to the detection output from the detection section 6. 7 measures that the predetermined communication time period has been reached, the line switching section 2 is shifted from the set state to the reset state, the telephone line is forcibly disconnected from the network control device 1, and the telephone line is forcibly disconnected from the network control device 1. The configuration is such that it connects to the telephone side.

Next, the network control device 1 shown in FIG.
The operation will be explained separately in the normal state and the measurement value data transmission state of the meter device.

First, when the network control device 1 is in a normal state, the telephone line is connected to the telephone side. That is, the control section 3 is driven by the current supplied from the power supply section 9, and makes the transistor Q5 conductive via the diode D1. As a result, a current path from the power supply unit 9 to the ground via the transistor Q5 is established, and electromagnetic force is induced in the coil L(R). This electromagnetic force is applied to switches RY1 and RY2
is connected to the reset terminals r1 and r2. Therefore, the line switching unit 2 is set to the normal reset state, so that normal telephone call signals are transmitted and received to and from the other party via the telephone line without affecting the internal signals of the network control device 1 at all. .

Now, when the network control device 1 is in a state to transmit the measured value data on the meter device side via the telephone line, the control section 3 connects the telephone line to the meter device side, that is, the network control device 1 side. The switching control operates as follows. It is assumed that the measurement data of the meter device is transmitted by a terminal call in response to interrupt control of a timekeeping mechanism by an internal timer (not shown) of the control unit 3.

[0039] When the terminal call is made, the control unit 3 obtains measurement value data of the meter device via the interface unit 8, and
Store this temporarily in internal memory. Thereafter, in order to set the line switching section 2 and connect the telephone line to the network control device 1 side, first, a predetermined voltage is applied to the gate side of the transistor Q4 to make the transistor Q4 conductive. As a result, a current path to ground via the power supply section 9, photocoupler PD2, and transistor Q4 is established, and the photocoupler PT2 of the line coupling section 4 becomes conductive. In parallel with this, since the transistor Q3 is also made conductive via the capacitor C4, a current path to ground via the power supply section 9, the resistor R8, the coil L(S), and the transistor Q3 is also established. At this time, the electromagnetic force induced in the coil L(S) acts to switch the connection of the switches RY1 and RY2 to the terminals S1 and S2. As a result, the line switching unit 2 shifts to the set state, and the telephone line is switched from the home telephone side to the network control device 1 side. Note that the power supplied from the switched telephone line is transferred to the line switching unit 2.
is detected as a current in the line current detection 6. At this time, the photocoupler PD1 emits light, and this light emission is received by the photocoupler PT1 near the timer section 7, so that the timer section 7 starts being supplied with power from the power supply section 9, and accordingly, the network control device 1 Start counting the hold time of the telephone line.

Now, as mentioned above, the photocoupler PT is made conductive by the conduction control of the transistor Q4 of the control section 3.
A line coupling unit 4 including 2 acts to couple a telephone line to the network control device 1 . In other words, photocoupler PT2
As a result of the conduction, the transistor Q2 to which a voltage is applied to its gate becomes conductive, and then the transistor Q1 becomes conductive. This connects the telephone line to resistor R7 and transformer T.
1, the transmission/reception signals between the telephone line and the network control device 1 pass through the line coupling section 4. Therefore, the control section 3 can send the meter measurement value data temporarily stored in its internal memory to the telephone line via the modem section 5.

Now, as described above, at the same time as the telephone line is terminated, the timer section 7 starts counting the line hold time period for the communication. In other words, the line current detection unit 6
Upon detection of the current, the photocoupler PD1 becomes conductive, power is supplied to the timer section 7 from the power supply section 9, and the resistor R19
A CR timer constituted by R20 and capacitor C3 operates. As mentioned above, this CR timer value is set in advance to a value that is sufficiently larger than the normal holding time period of the telephone line in the network control device 1. The network control device 1 operates as follows depending on whether or not the communication by the terminal call is continued beyond the CR timer value to avoid the telephone line from being put on hold more than necessary.

[0042] First, a case will be described in which the network control device 1 normally ends communication within a predetermined time period.

[0043] Within a predetermined time period based on the CR timer value, the control unit 3 receives a signal indicating that the communication has ended normally via the telephone line, and upon detecting the normal end of the communication, responds by turning on the diode. Through D1, transistor Q
5 is controlled to conduct. As a result, the power supply section 9,
A current path to ground through resistor R14, coil L(R) and transistor Q5 is established, and coil L(R)
The induced electromagnetic force acts to connect the switches RY1 and RY2 to the terminals r1 and r2. As a result, the line switching unit 2 shifts from the set state to the reset state, and the telephone line is disconnected from the network control device 1 and connected to the telephone side, and the state shifts to a state where normal telephone calls can be made. .

As described above, since the line switching unit 2 has transitioned from the set state to the reset state, the line coupling unit 4 operates to disconnect and open the line from the network control device 1 through the resistor R7 and the transformer T. do. Thereafter, call signals generated by the use of the telephone will not leak into the network control device 1.

Next, the communication operation in the network control device 1 is as follows.
A communication abnormality that continues even after the timer section 7 finishes counting for a predetermined period of time will be described.

[0046] If the communication by the terminal call in the network control device 1 described above falls into an abnormal state due to an abnormality in the network control device 1 itself or a line error in the telephone line, that is, if the line coupling section 4 If the state where the telephone line is terminated at is maintained for more than the predetermined period of time, it becomes impossible to make subsequent calls using the telephone. In order to avoid such an abnormal state, the network control device 1 operates as follows.

When the line holding time due to the terminal call described above exceeds the CR timer value, the voltage level applied to the non-inverting input terminal side of the operational amplifier OP of the timer section 7 changes to the resistor R21 applied to the inverting input terminal side. Since the output voltage exceeds the voltage dividing level (fixed) by R22, the output of the operational amplifier OP becomes active, and the transistor Q5 becomes conductive accordingly. Therefore, the power supply section 9, the resistor R14, the coil L (
R) and to ground through transistor Q5, the electromagnetic force induced in coil L(R) causes switches RY1 and RY2 to reset terminals r1 and r
It acts to switch the connection to the 2nd side. As a result, the line switching section 2 shifts from the set state to the reset state, and the telephone line is disconnected from the network control device 1, released from the hold state, and switched to the telephone side. Therefore, since signals from subsequent calls do not leak into the network control device 1, individual processing can be performed to recover the network control device 1 from the abnormal state.

[0048] When the network control device 1 returns to the normal state from the abnormal state, it continues the interrupted communication. To this end, the control unit 3 first detects the idle state of the telephone line, and accordingly controls the transistors Q4 and Q3 to conduct, thereby inducing electromagnetic force in the coil L(S). This results in
The switches RY1 and RY2 of the line switching section 2 are connected again to the set terminals S1 and S2, and the interrupted communication can be resumed.

As described above, when a line holding state occurs in the network control device 1 for more than a predetermined time period due to an abnormality inside the network control device 1 or a line error in the telephone line, the timer section 7 The overage is detected and the detection output acts to release the hold state of the telephone line. Therefore, unnecessary holding of the telephone line due to the line hold state is avoided, and the line can be used effectively.

[0050]

According to the present invention, when a line holding state occurs due to a failure or malfunction in the network control device, or a line error in the communication line due to external noise, the timer measures the line holding time. When the time period reaches a predetermined time period, the line release means releases the communication line from the hold state, so that the communication line can be provided for other communication operations, and the communication line can be used effectively. There is an effect.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a circuit configuration of a network control device according to an embodiment of the present invention.

FIG. 2 is a schematic block diagram showing the configuration of a data communication system to which a network control device according to a conventional example and an embodiment of the present invention are applied.

[Explanation of symbols]

1 Network control device 2 Line switching section 3 Control section 4 Line connection part 6 Line current detection section 7 Timer section In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A network control device that connects a communication line and a plurality of data terminal devices, the line coupling the communication line to the network control device in response to a communication start request from each of the plurality of data terminal devices. a coupling means, a timer for timing the hold time of the line by the line coupler, and a line release means for releasing the line from the hold state when the time period measured by the timer reaches a predetermined time period. A network control device equipped with