JP3542058B2 - Terminal network controller - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a terminal network control device for automatically collecting meter readings of a gas meter, a water meter, and the like from a center using a telephone line.
[0002]
[Prior art]
Conventionally, when a dial (10 pps or 20 pps) is dialed by the terminal network control device, when an attached telephone is provided, a dial pulse (DP) causes the bell of the attached telephone to ring, a phenomenon called resonance. For this reason, it is common practice to temporarily disconnect the attached telephone from the telephone line during the DP dial of the terminal network control device.
[0003]
[Problems to be solved by the invention]
However, if the attached telephone is temporarily disconnected from the telephone line during the DP dial of the terminal network control device, the outgoing call (off-hook) from the attached telephone cannot be detected during this time, resulting in a problem that the service is deteriorated. I do.
SUMMARY OF THE INVENTION It is therefore an object of the present invention to enable the outgoing call (off-hook) of an attached telephone to be detected even during the DP dial of the terminal network control device, thereby avoiding a drop in service.
[0004]
[Means for Solving the Problems]
Switching means such as a relay circuit controlled by a control unit including a microcomputer (also referred to as a microcomputer) is provided. During the DP dial, high resistance, charge / discharge means including a capacitor, current detection means including a photocoupler, and other resistors are provided. By connecting a series circuit with the line between the lines, forming a current loop when the attached telephone is off-hook, discharging the charged charge in the charging / discharging means, and detecting the current flowing as a result by the current detecting means. Off-hook of the attached telephone can be detected even during dialing, and resonance of the attached telephone is prevented by the voltage dividing action of the high resistance and the series circuit. Thereby, it is possible to prevent the service for the user from being lowered.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a circuit diagram showing an embodiment of the present invention.
That is, the terminal network control device 4 according to the present invention is electrically connected to the meter reading meter 5, while being connected to the center automatic meter reading device 1 via the telephone network 2. The terminal network control device 4 itself includes a line control unit 41, a modem (modem) unit 42, a control unit 43 including a microcomputer, a relay circuit 44, a photocoupler PC, resistors R1, R2, R3, and a capacitor C. .
[0006]
Further, the terminal network control device 4 includes an attached telephone 3 including a telephone internal circuit 31, a switch 32, a bell circuit 33, and the like. When the telephone 3 is not off-hook, the switch 32 forming the DC loop circuit is open, and the DC impedance seen from the terminals T1 and T2 is very large. On the other hand, when the hook is off-hook, the switch 32 of the DC loop circuit is closed, so that the DC impedance drops to R4. The bell circuit 33 is always connected between the lines.
[0007]
The operation of FIG. 1 will be described.
First, when the center automatic meter reading device 1 and the meter reading meter 5 are not communicating, the control unit 43 of the terminal network control device 4 sets the relay circuit 44 to the contact a side. Thereby, the attached telephone 3 is connected between the telephone lines L1 and L2, and the user can use the telephone at any time.
[0008]
Next, when communication is performed between the center automatic meter reading device 1 and the meter reading meter 5, the control unit 43 sets the relay circuit 44 to the contact b side before starting communication, and sets the capacitor C, the resistors R1, R2 and the photocoupler. An off-hook detection circuit such as a PC is connected to the telephone lines L1 and L2. Since the voltage supplied to the telephone lines L1 and L2 is applied to the off-hook detection circuit, the capacitor C is slowly charged by the high resistance R1 and R2. The high resistance R1 is designed to sufficiently attenuate the dial pulse signal between the terminals T1 and T2 so that the bell of the attached telephone does not malfunction (resonate) with the dial pulse output from the line control unit 41 of the terminal network control device 4. , R and the bell circuit and C and R2.
[0009]
In such a configuration, when the attached telephone goes off-hook, the switch 32 closes, so that a DC loop is formed between the terminals T1 and T2 by the resistor R4. As a result, the current previously charged in the capacitor C flows in the loop of the C-R2-PC-relay circuit 44-terminal T2-switch 32-R4-terminal T1-C, turning on the transistor of the photocoupler PC, The control unit 43 is notified of the off-hook of the attached telephone. As a result, the control unit 43 immediately switches the relay circuit 44 to the b side, and releases the telephone lines L1 and L2 to the user.
[0010]
When the relay circuit 44 is switched by an external shock or the like during a period other than during communication and the attached telephone is disconnected from the line (connected with a high resistance R1), the control is performed by off-hooking the attached telephone. Since the off-hook detection signal is input to the unit 43, the control unit 43 knows that the relay circuit 44 has operated due to an impact or the like, and can switch the relay circuit 44 to the a side to release the telephone line to the user. .
[0011]
【The invention's effect】
According to the present invention, since the off-hook of the attached telephone can be detected by the line control unit even during dialing, there is an advantage that the service to the user can be prevented from deteriorating. In addition, since a malfunction of the relay circuit can be detected, the reliability of the device can be improved.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an embodiment according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Automatic meter reading apparatus, 2 ... Telephone network, 3 ... Attached telephone, 4 ... Terminal network control apparatus, 5 ... Meter reading meter, 31 ... Telephone internal circuit, 32 ... Switch, 33 ... Bell circuit, 41 ... Line control part, Reference numeral 42 denotes a modulation / demodulation unit (modem unit), 43 denotes a control unit (microcomputer), 44 denotes a relay circuit, and PC denotes a photocoupler.

Claims (1)

A line control unit for performing data communication with a center automatic meter reading device via a telephone line, a modem connected to the line controller, and a terminal network controller including a controller for controlling the modem and the line controller At
The other end of the attached telephone, one end of which is always connected to one end of the telephone line, is connected to the other end of the telephone line via a high resistance during the DP dial, and the charge / discharge means, current detection means, and other resistances are connected. Switching means controlled by the control unit is provided for connecting to one end of a telephone line through a series circuit and connecting the other end of the attached telephone to the other end of the telephone line except during a DP dial. The electric charge charged in the charging / discharging means is discharged through a current loop formed when the attached telephone is off-hook, and the resulting current is detected by the current detecting means. A terminal network control device, wherein a resonance of an attached telephone can be prevented by a voltage dividing action with a circuit.

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