JP2958230B2 - Terminal network controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terminal network control used in a telemeter system for performing no-ringing communication or terminal calling communication of terminal equipment for measuring water, gas, electricity, etc., via a general telephone line. Related to the device.

[0002]

2. Description of the Related Art Generally, a data transmission method using a general telephone line is the most practical as a method for collecting information on sales volume in an automatic meter reading in households such as water supply, gas and electricity or in a vending machine. It is rich. Among these systems, there is a no-ringing communication system for performing data communication without ringing the bell of a telephone. When such data communication is performed, the use state of the telephone is monitored, and when the telephone is off-hook, the communication is interrupted. When the telephone is on-hook, the communication between the terminal network controller (T-NCU) and the center-side device is performed. Perform data communication.

Here, a conventional terminal network controller is shown in FIGS.
Shown in 4 and 5, 1 is a T-NCU, 2 is a telephone, 3 and 4 are terminal equipment such as meters and sensors, 5 is an off-hook detection circuit, 6 is a polarity reversal detection circuit, 7 is a terminal calling circuit, and 8 is a terminal calling circuit. No ringing signal (NRS) detection circuit, 9 is a half loop control circuit, 10 is a modem circuit, 11 is a main control circuit, 12 is a connection switching circuit, 13 is a power supply circuit, 14 is a clock circuit, 15 and 16 are meters, sensors, and the like. Interface circuit, L1 and L2 are telephone lines, T1 and T2 are telephones 2
Line terminal.

[0004] In the off-hook detection method of the T-NCU 1, prior to the start of the communication operation, it is confirmed whether or not a current is flowing to the photocoupler PC4. If a current is flowing, the main control unit 11 determines that the terminal is off-hook, and if no current is flowing, determines that the terminal is on-hook and starts the terminal calling operation. When the terminal calling communication is started, the telephone 2 is switched by the relay RY to the lines L1 and L1 to secure the attenuation of the communication message.
It is separated from L2 so that the message is not transmitted to the telephone 2. Then, during communication, a detection voltage (a value smaller than the line voltage) equivalent to that of the main control circuit 11 is applied to the telephone 2 from the power supply Vt, and the division ratio of the detection voltage at this time is measured. Detect if it is off-hook.

In this case, when the T-NCU 1 is performing no-ringing communication, the off-hook detection voltage of the telephone 2 is:
Since the impedance of the T-NCU 1 is large, off-hook detection can be performed at a value substantially close to the line voltage.

However, when the T-NCU 1 makes a normal terminal call, the line voltage decreases because the impedance of the T-NCU 1 becomes the same value as the impedance of the telephone 2 in the off-hook state. This is the line L1
Is higher than the line L2, the relay R
When Y is switched, the backflow is prevented by the diode D3. At this time, the voltage between the line terminal T1 and the line terminal T2 of the telephone 2 is maintained at the line voltage if the communication time is short. If the communication time is long, the line terminal T1
The voltage between the terminal and the line terminal T2 gradually decreases. Further, when the voltage of the line L2 is higher than the voltage of the line L1, the discharge is immediately performed when the relay RY switches, and the line voltage drops rapidly. When this voltage is used, the off-hook detection voltage of the telephone 2 is the normal line voltage (48 V).
This is an extremely small value as compared with.

[0007]

However, with the recent development of electronic technology, electronic telephones having a line voltage detecting function have become widespread.
Unless a normal line voltage is applied to T1 and T2, many devices do not operate correctly.

[0008] Such a telephone 2 is connected to a conventional T-NCU 1
In the case of terminal call communication, the T-NCU 1 disconnects the telephone 2 from the lines L1 and L2 and monitors the telephone 2 with a detection voltage lower than the normal line voltage, so that the impedance of the telephone 2 becomes indefinite, There has been a problem that the telephone 2 does not operate normally and off-hook detection cannot be performed normally.

Further, in the conventional 600-type telephone set, the change in impedance can be detected regardless of the line voltage in the off-hook detection. However, when the polarity of the line voltage is changed due to, for example, construction work, a bell may be sounded for a moment during communication.
As a result, the user is mistaken for the ringing of a normal telephone, which is unpleasant and unpleasant.

In view of the above, it is an object of the present invention to provide a terminal network control apparatus for monitoring off-hook by applying a voltage having the same value and the same polarity as a line voltage to a telephone at the time of calling a terminal.

[0011]

The object of the present invention is to monitor the use state of the telephone 27 as shown in FIG.
A terminal network control device for performing data communication with the center device using the telephone lines L1 and L2 when the telephone set 27 is on-hook. Polarity detecting means 52 for determining the polarity of the line voltage, off-hook monitoring means 53 for monitoring the telephone 27 by applying a voltage having the same value as the line voltage to the telephone 27, and an output signal from the polarity detecting means 52 And a polarity switching means 54 for switching the polarity of the applied voltage of the off-hook monitoring means 53 based on the

An update registration means 63 is provided for updating the polarity detected when data communication is performed.

[0013]

In the above-mentioned means for solving the problems, the telephone 2
7 is detected, the telephone lines L1, L
2. Disconnect the telephone 27 from 2. Then, a voltage having the same value as the line voltage is supplied to the telephone 2 by the off-hook monitoring means 53.
7 to monitor the use state of the telephone 27. At this time, the polarity detecting means 52 determines the polarity of the line voltage of the telephone lines L1 and L2, and the polarity switching means 54 switches the polarity of the applied voltage of the off-hook monitoring means 53 according to the polarity of the voltage. Therefore, a voltage having the same value and the same polarity as the line voltage is always applied to the telephone set 27.

The polarity of the voltage determined by the polarity detection means 52 is stored in the update registration means 63, and is rewritten to a new polarity every time communication is performed.

[0015]

FIG. 1 is a block diagram of a terminal network control device according to an embodiment of the present invention, FIG. 2 is an electric circuit diagram of an off-hook detection circuit of the present embodiment, and FIG. FIG. 1 is a system configuration diagram of a no-ringing communication system provided.

In the no-ringing communication system shown in FIG. 3, reference numeral 21 denotes a host computer, 22 denotes a center network control unit (C-NCU), 23 denotes an exchange connected to the center, and 24 denotes an exchange connected to the terminal. Station, 25 is a no-ringing trunk used in no-ringing communication, 26 is a terminal network controller (T-NCU), 27 is a telephone, 28 and 29 are terminal equipment such as meters and sensors, 30 is an interoffice trunk line, 31 and 32 is an interface line between the terminal exchange and the no-ringing trunk;
5 and 36 are connection lines, and L1 and L2 are telephone lines.

As shown in FIG. 1, the T-NCU 26 includes an off-hook detection circuit 40 for monitoring the use state of the telephone 27.
A connection switching circuit 41 for disconnecting the telephone 27 from the telephone lines L1 and L2 when monitoring the telephone 27;
A polarity inversion detection circuit 42 for detecting the inversion of the line voltage from L2, a terminal calling circuit (including a full-wave rectification circuit using a diode bridge (not shown)) 43 for performing a dial operation and an off-hook operation, and a no ringing signal after the detection of the polarity inversion Signal (NRS) detection circuit 44 for detecting whether the signal is the terminal itself and a half-loop control circuit 45 for controlling communication at the time of no ringing communication
And a modem circuit 4 for transmitting and receiving data to and from the center device.
6, interface circuits 47 and 48 for communicating with the meter 28 and the sensor 29, a power supply circuit 49 for supplying power to each section, a clock circuit 50 for supplying a clock signal and measuring time and the like, a microcomputer, etc. And a main control circuit 51 comprising: And the telephone line L
An off-hook detection circuit 40, a polarity inversion detection circuit 42, a terminal calling circuit 43, an NRS detection circuit 44, a half-loop control circuit 45, and a modem circuit 46 are connected to 1 and L2. The main control circuit 51 includes an off-hook detection circuit 40, a polarity reversal detection circuit 42, a terminal calling circuit 43, an NR
S detection circuit 44, half loop control circuit 45, modem circuit 4
6, each interface circuit 47, 48, power supply circuit 4
9, and a clock circuit 50 are connected.

The connection switching circuit 41 is interposed between the telephone 27 and the off-hook detection circuit 40. The connection switching circuit 41 comprises a relay RY as shown in FIG. 2, and a call position where the telephone lines L1 and L2 are connected to the line terminals T1 and T2 of the telephone 27 by a1 and a2 contacts, and b
The switching between the circuit terminals T1 and T2 and the monitoring position where the off-hook detection circuit 40 is connected can be freely switched by the contacts 1 and b2.

The T-NCU 26 monitors the use state of the telephone 27, interrupts data communication when the telephone 27 is off-hook, and performs data communication with the center device when the telephone 27 is on-hook. Do.

When the T-NCU 26 makes a call to the center network control device 22, the modem circuit 46 transmits communication data to the general telephone lines L1 and L2 according to a command from the main control circuit 51. At this time, the use state of the telephone 27 is monitored by switching the relay RY from the talking position of the a1 and a2 contacts to the monitoring position of the b1 and b2 contacts, applying a detection voltage to the telephone 27, and changing the detection voltage.
It is detected whether or not is in use.

In the off-hook detecting circuit 40, as shown in FIG. 2, a polarity detecting means 52 for determining the polarity of the line voltage of the telephone lines L1 and L2 at the time of making a call to the center device, as shown in FIG. A power supply conversion circuit as off-hook monitoring means 53 for applying a voltage having the same value as the line voltage to the telephone 27 to monitor the telephone set 27, and a polarity of an applied voltage of the power supply conversion circuit 53 based on an output signal from the polarity detection means 52 And a polarity conversion circuit as polarity switching means 54 for switching between the two.

The polarity detecting means 52 includes a telephone line L1,
Photocouplers PC1 and PC2 connected to L2,
Each light emitting diode 55 of the photocouplers PC1 and PC2
a and 56a are connected in parallel, and are interposed between the line L1 and the polarity reversal detection circuit 42. Line L
1, a resistor R1 is connected between the photocouplers PC1 and PC2. In addition, the phototransistors PC1 and PC2 have their secondary sides connected in parallel to the phototransistors 55b and 56b of the photocouplers PC1 and PC2, and the emitter terminals of the phototransistors 55b and 56b connected to the main control circuit 51. I have. This photo coupler PC1, P
C2 detects whether a current (line voltage: 48 V) is flowing through the lines L1 and L2 prior to the start of communication, and determines the voltage polarity of the current flowing through the photocouplers PC1 and PC2 at the start of communication. When current flows through either the photocoupler PC1 or the photocoupler PC2, the phototransistors 55b and 56b of the photocouplers PC1 and PC2.
Is turned on and transmitted to the main control circuit 51. At this time, the voltage polarity of the flowing current is such that when the line L1 has a higher potential than the line L2, the current flows through the photocoupler PC1,
When the main control circuit 51 determines that the potential is positive, and when the potential of the line L2 is higher than that of the line L1, a current flows through the photocoupler PC2, and the main control circuit 51 determines that the potential is negative.

The contact a1 of the relay RY is connected to an intermediate point between the photocouplers PC1 and PC2 and the polarity inversion detecting circuit 42, and the contact a2 of the relay RY is connected to an intermediate point between the line L2 and the polarity inversion detecting circuit 42. Connected, relay RY
A resistor R2 is connected between the contact a1 and the line L1. When the relay RY switches to the monitoring position of the contacts b1 and b2, the telephone set 27 is disconnected from the telephone lines L1 and L2.

The power supply conversion circuit 53 includes a D / D converter 57 for converting a DC voltage into an AC voltage, and a clock circuit 50.
And a buffer circuit 58 for operating the D / D converter 57 by the oscillation signal from

The D / D converter 57 converts the DC input into AC using the oscillation frequency of the clock circuit 50, and generates a voltage of ± 48 V, which is the same as the line voltage, using a transformer.
Each voltage is applied to the telephone 27. The connection line 59a on the positive electrode side is connected to the contact b1 of the relay RY via the diode D2, the connection line 59b is connected to the contact b2 of the relay RY, and the connection line 60a on the negative electrode. Is connected to the connection line 59a on the positive electrode side via the diode D1, and the connection line 60b is connected to the connection line 59b on the positive electrode side. Diode D1
And a resistor R8 are connected in series to the diode D2. Also, the connection line 60 on the negative electrode side
a and 60b are connection lines 61a from the terminal calling circuit 43,
61b is connected. Then, the buffer circuit 58
Converts the oscillation signal from the clock circuit 50 into impedance, thereby stabilizing the operation of the clock circuit 50. Further, since the oscillation signal is controlled by the main control circuit 51, the D / D converter 57 can be operated with good timing.

The polarity conversion circuit 54 includes a power supply conversion circuit 5
3 and a relay RX interposed between the relay RY and a positive electrode position connected to the positive-side connection lines 59a and 59b of the D / D converter 57 by contacts a1 and a2, and b
The contacts 1 and b2 can be switched between a negative position connected to the connection lines 60a and 60b on the negative side of the D / D converter 57. The relay RX is switched to the positive position by an output signal from the main control circuit 51 when a current flows through the photocoupler PC1, and is switched to the negative position when a current flows through the photocoupler PC2. Polar voltage is applied. A photocoupler PC3 is interposed between the relay RX and the relay RY. The phototransistor 62b on the secondary side of the photocoupler PC3 is connected in parallel with the phototransistors 55b and 56b of the photocouplers PC1 and PC2. It is connected. The photocoupler PC3 detects whether or not a current flows between the relay RX and the b1 contact of the relay RY during communication. When the telephone 27 is off-hook in the off-hook monitoring state, the photocoupler PC3 When the switches SW provided on the line terminals T1, T2 and the telephone lines L1, L2 are switched, the light emitting diode 62 of the photocoupler PC3 is switched.
A current flows through a, and the secondary-side phototransistor 62b is turned on and transmitted to the main control circuit 51. Then, the communication operation is interrupted by an output signal from the main control circuit 51, the switch SW is turned off, the relay RY is switched to the talk position, and the lines L1 and L2 are connected to the telephone. In addition,
A resistor R6 is connected between the photocoupler PC3 and the relay RX, and a capacitor C1 is connected in parallel between the relays RY and RX.

The main control circuit 51 is provided with an update registration means 63 for updating the polarity detected when data communication is performed. The update registering means 63 stores the polarity of the line voltage determined by the polarity detecting means 52, and rewrites the stored polarity to the polarity of the line voltage at the time of each communication. As a result, even if the voltage polarities of the exchange 24 and the T-NCU 26 are exchanged due to work or the like, the relay RX is switched to the positive position or the negative position according to the polarity, so that the polarities can be automatically adjusted. it can.

In the above configuration, when a call request is issued from terminal equipment such as the meter 28 and the sensor 29 connected to the T-NCU 26, the T-NCU 26
When the communication is started, the main control circuit 51
Confirms whether a current is flowing through the photocouplers PC1 and PC2. In this case, either photocoupler P
If a current is flowing through C1 and PC2, the telephone 27 is in an off-hook state and waits until the telephone 27 enters an on-hook state.
If no current is flowing, the telephone 27 is in the on-hook state, so that communication is started. At this time, T-NCU
Until the terminal 26 starts communication, the output of the full-wave rectifier circuit (diode bridge) (not shown) in the terminal calling circuit 43 is charged to the line voltage by the capacitor C1 via the resistor R7, the diode D1, and the resistor R6.

Next, when communication is started, first, the relay R
Y switches to the monitoring position of the b1 and b2 contacts, and the telephone set 27 is disconnected from the lines L1 and L2 to enter an off-hook monitoring state. Then, current flows to either the photocoupler PC1 or the photocoupler PC2. At this time,
The main control circuit 51 confirms which of the photocouplers PC1 and PC2 the current flows, and determines that the voltage is the positive voltage for the photocoupler PC1 and the negative voltage for the photocoupler PC2. The contact of the relay RX is switched to the positive position or the negative position. The update registration means 63 stores the determined voltage polarity.

Then, the D / D converter 57 is operated by the oscillation signal from the clock circuit 50, and the D / D converter 57 generates the same voltage of 48 V as the line voltage. The off-hook is monitored, and the communication is continued. At this time, the polarity of the voltage applied to the telephone set 27 is the same as the voltage polarity of the current flowing through the lines L1 and L2 by the switching of the relay RX.

If the telephone set 27 goes off-hook during communication, a current flows through the photocoupler PC3 and is transmitted to the main control circuit 51. The communication operation is immediately interrupted, and the relay RY is connected to the a1 and a2 contacts. Then, the telephone lines L1 and L2 are connected to the telephone 27 side.

As described above, when monitoring the off-hook state of the telephone 27 during communication, the D / D converter 57 generates a voltage of 48 V, which is the same as the line voltage, and applies the voltage to the telephone 27. The off-hook of the telephone 27 can be monitored at the same voltage as the line voltage. Therefore, even if the connected telephone 27 is an electronic telephone or a 600-type telephone having a line voltage detection function, the telephone 27 does not malfunction and normal off-hook detection can be performed.

Since the voltage polarities of the telephone lines L1 and L2 are determined by the photocouplers PC1 and PC2 and the polarity of the voltage from the D / D converter 57 is switched by the relay RX, the voltage of the telephone lines L1 and L2 is changed. According to the polarity, a voltage having the same polarity as the line voltage can be applied to the telephone set 27. Therefore, even if the polarity of the line voltage is changed due to construction work or the like, the polarity of the line voltage can always be matched. Therefore, even if the telephone 27 is a 600-type telephone, the bell does not ring and does not use. It does not cause discomfort to the person.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that many modifications and changes can be made to the above-described embodiment within the scope of the present invention.

[0035]

As is apparent from the above description, according to the present invention, when monitoring the off-hook state of the telephone, a voltage having the same value as the line voltage is generated by the off-hook monitoring means, and the voltage is applied to the telephone. Therefore, the off-hook of the telephone can be monitored at the same voltage as the line voltage. Further, since the polarity of the telephone line is determined by the polarity detecting means and the polarity of the applied voltage of the off-hook monitoring means is switched by the switching means, the telephone has the same polarity as the line voltage according to the voltage polarity of the telephone line. A voltage can be applied.

Therefore, even if the connected telephone is an electronic telephone or a 600-type telephone having a line voltage detecting function, normal off-hook detection can be performed without malfunction of the telephone. Also, even if the polarity of the line voltage is changed due to construction work or the like, the polarity of the line voltage can always be matched. Therefore, even if the telephone is a 600-type telephone, the bell does not ring and the user does not hear the bell. It does not give any discomfort.

Then, the polarity of the line voltage determined by the polarity detection means is stored by the update registration means, and each time communication is performed, the stored polarity is rewritten to the polarity of the line voltage at that time. There is an excellent effect that the polarities can be automatically adjusted even if the voltage polarities are changed due to work or the like.

[Brief description of the drawings]

FIG. 1 is a block diagram of a terminal network control device according to an embodiment of the present invention.

FIG. 2 is an electric circuit diagram of an off-hook detection circuit according to the present embodiment.

FIG. 3 is a system configuration diagram of a no-ringing communication system including a terminal network control device.

FIG. 4 is a block diagram of a conventional terminal network control device.

FIG. 5 is an electric circuit diagram of a conventional off-hook detection circuit.

[Explanation of symbols]

 26 Terminal Network Controller 27 Telephone 52 Polarity Detecting Means 53 Off-Hook Monitoring Means 54 Polarity Switching Means 63 Update Registration Means

Claims (2)

(57) [Claims] 1. A terminal network control device for monitoring a use state of a telephone and performing data communication using a telephone line with a center device when the telephone is on-hook. Polarity detection means for determining the polarity of the line voltage of the telephone line at the time of calling, off-hook monitoring means for monitoring the telephone by applying a voltage having the same value as the line voltage to the telephone, and A terminal switching unit for switching a polarity of an applied voltage of the off-hook monitoring unit based on an output signal. 2. The terminal network control device according to claim 1, further comprising update registration means for updating the polarity detected when data communication is performed.