JP3095321B2 - 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 device used in a data communication system for transmitting data from a security meter such as a meter or a sensor or an emergency button using a telephone line. About.

[0002]

2. Description of the Related Art At present, a data communication system for communicating meter reading information such as gas and water at home or security information such as emergency or abnormal situation using a telephone line has become widespread. This is because a terminal device such as a meter or a security device is connected to a terminal network control device provided on the user side, and the main control unit of the terminal network control device performs control on the center side based on a signal from the terminal device. It performs data communication with the device.

A terminal device is connected to a connection terminal of a terminal network control device by a connection line, and is connected from the connection terminal to a main control unit via an interface (I / F) unit. The I / F section includes a meter I / F section corresponding to each terminal device and a security device I / F section.

A typical I / F unit for meters is a standard I / F unit of the Ministry of Posts and Telecommunications, or a photocoupler unit. The former is shown in FIG. I / F for this meter
The unit 1 includes PNP transistors Tr1 and NP as shown in FIG.
It comprises an N transistor Tr2, an NPN transistor Tr3, and resistors R61 to R69. The transistor Tr1 has a collector terminal connected to a connection terminal Q1 connected to a connection line of a meter via a resistor R61, and an emitter terminal connected to a power supply Vcc. The transistor Tr2 has its emitter terminal connected to the connection terminal Q2 to which the connection line of the meter is connected and is grounded to ground, and its collector terminal is connected to the intermediate point between the connection terminal Q1 and the resistor R61 via the resistor R62. It is connected. Further, the transistor Tr1 and the transistor Tr
2 are connected to the ports P10 and P11 of the main control unit via resistors R66 and R67, respectively. On the other hand, the transistor Tr3 has a base terminal connected to an intermediate point between the resistor R61 and the connection terminal Q1, a collector terminal connected to the port P12 of the main control unit, an emitter terminal grounded, a collector terminal and the main control terminal. The resistor R65 is connected between the connection point of the port P12 of the unit and the power supply Vcc. Further, resistors R68, R69, and R64 are connected between the base and the emitter of each of the transistors Tr1, Tr2, and Tr3, respectively.

In the meter I / F section 1, the I / F
When self-checking whether the unit 1 operates normally or not, first, when the transistor Tr1 is turned on, a low (L) level signal is output to the port P12 of the main control unit because the meter side has a high impedance. Is entered.
Further, when the transistor Tr2 is turned on, the port P
12, a high (H) level signal is input. As a result, it is determined that the I / F unit 1 is operating normally.

FIG. 7 shows a typical I / F section for a security device.
4. It is composed of a diode D1 and resistors R71 and R72. The transistor Tr4 has an emitter terminal connected to the connection terminal U1 connected to the connection line of the security device, a collector terminal connected to the port P13 of the main control unit, and a base terminal connected to the security device via the resistor R72. It is connected to the connection terminal U2 connected to the line and is grounded to the ground. A power supply Vcc is connected via a resistor R71 to an intermediate point between the collector terminal of the transistor Tr4 and the port P13 of the main control unit, and branches from the base terminal of the transistor Tr4 and the resistor 72 to perform main control. Is connected to the port P14, and a diode D is connected between the base and the emitter of the transistor Tr4.
1 is connected.

When self-checking the security device I / F 2, the transistor Tr4 is turned on and off. At this time, if the security device is turned on, the connection terminal U1 goes to L level, so that L and H level signals are input to the port P13 of the main control unit,
/ F unit 2 is determined to be operating normally.

As another I / F section for security equipment, there is an I / F section to which the transistor Tr4 shown in FIG. 7 is not connected. This is because the state of the security device is directly input to the port P13 of the main control unit, and when the on / off state of the security device is detected, processing is performed in a software manner by a hardware interrupt. That is, when the port P13 rises from the L level to the H level, it is determined that the security device is off, and the port P13 is turned off.
It is determined that the switch 13 is on when the signal 13 falls from the H level to the L level.

However, in this system, if the security device is turned on, the current from the power supply Vcc is applied to the resistor R
71, connection terminal U1, security device, connection terminal U2
, The current always flows in the order of ground, so that the battery is quickly consumed and inconvenient. Therefore, as shown in FIG. 7, a method has been adopted in which the transistor Tr4 is provided and the current consumption is reduced by intermittently operating the transistor Tr4.

[0010]

However, in the conventional security device I / F unit 2, when the self-check is performed and the security device is turned off, the connection terminal U1 becomes high impedance. Is turned on or off, no L or H level signal is input to the port P13 of the main control unit, so that the self-check cannot be performed. In addition, there is a problem that it cannot be determined whether the security device is off or the connection line to the security device is broken.

Therefore, the present applicant has disclosed a method of connecting a diode (LED) in parallel to the emergency button and detecting a connection state between the emergency button and the central control device by a detection circuit provided in the central control device. No. 4,82,794. However, in this method, although the disconnection of the connection line can be detected, the security device I
Similarly to the / F unit 2, the self-check of the I / F unit could not be performed due to the ON / OFF state of the emergency button. In addition, a circuit for flowing a current in the forward direction and the reverse direction in the diode connected in parallel is required, and the configuration and control of the I / F section are complicated, leading to an increase in cost and an increase in the size of the device.

The security device I / O shown in FIG.
When the on / off state of the security device is detected by intermittently operating the transistor Tr4 in the F section 2, when the security device is on, the transistor T4 is turned on.
An L-level signal is input to the port P13 of the main control unit irrespective of the operation of r4, so that it can be determined that the switch is on. However, when the security device is off, L and H are applied to the port P13 by the operation of the transistor Tr4.
Since the signal of the level is intermittently input, an interrupt which is detected by hardware cannot be used, and it is difficult to process the software.

Further, each of the I / F sections 1 and 2 for the meter and the security device has a dedicated circuit configuration, and the input logic to the main control section is reversed and the impedance does not match. Both I / F sections 1 and 2 could not be shared.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a terminal network control device capable of checking a connection state with a terminal device and an internal state of the I / F section by one I / F section.

[0015]

As shown in FIG. 1, the terminal solving means according to the present invention is connected to terminal equipments 15 and 16 of meters and security equipment, and is connected to the terminal equipments 15 and 16 using a telephone line 13. I / F 23 based on the signal of
And a connection state detecting means 25 for detecting a connection state between the terminal device 16 and the I / F unit 23 by the main control unit 18 via the main control unit 18 via the The self-state detecting means 26 for detecting the internal state of the / F section 23 is provided. The connection state detecting means 25 includes resistors R81 and R82 having values different from those of the resistor Rs provided in the terminal device 16, and a voltage division between the resistors R81 and 82 and the resistor Rs of the terminal device 16. The connection line 2 between the terminal device 16 and the I / F unit 23
4 comprises a disconnection detecting circuit 27 for detecting whether or not a disconnection occurs. In addition, the self-state detecting means 26 includes the I / F unit 2
A switch 31 for separating the terminal 3 from the terminal device 16 and an operation detection circuit 33 for detecting whether or not the I / F unit 23 operates normally.

By matching the input logic and impedance to the main control unit 18, the I / F units 22 and 23 for the meter and the security device can be shared.

Further, in order to detect the on / off state of the terminal device 16, an intermittent power supply is supplied to the I / F unit 23, and an on / off detection circuit for detecting the on / off state of the terminal device 16 when the power is supplied. 36 are provided.

[0018]

In the above means for solving the problems, the terminal device 16 and the I
When detecting the connection state with the / F section 23, the current from the power supply Vcc is supplied to the terminal device 16 via the resistors R81 and R82. At this time, when the terminal device 16 is off, connection is made when an L-level signal is input to the main control unit 18 due to the voltage division between the resistors R81 and R82 of the disconnection detection circuit 27 and the resistor Rs of the terminal device 16. The line 24 is determined not to be disconnected, and if it is at the H level, it is determined to be disconnected. On the other hand, when the terminal device 16 is on, it is determined that there is no disconnection when an H-level signal is input to the main control unit 18 and that disconnection is performed when an L-level signal is input to the main control unit 18. In the case of a disconnection, the information is notified to the center-side device 11 by the main control unit 18.

Next, when performing a self-check of the I / F section 23, first, the changeover switch 31 is turned off to disconnect the terminal device 16 from the I / F section 23. Then, when the current flows through the operation detection circuit 33, the L-level and H-level signals are input to the main control unit 18 without being affected by the ON / OFF state of the terminal device 16. Thus, it is determined that the I / F unit 23 is normal.

Further, by sharing the I / F unit 23 for the meter and the security device, communication of both the meter and the security device becomes possible with one I / F unit, and the number of parts can be reduced.

Further, when the on / off state of the security device 16 is detected, intermittent power supply to the I / F unit 23 is performed. Then, a hardware interrupt is generated by the on / off detection circuit 36, and the same processing as when power is constantly supplied is performed, so that the on / off state of the terminal device 16 can be detected.

[0022]

FIG. 2 shows a data communication system provided with a terminal network control device according to this embodiment. In FIG. 2, 11 is a center device, 12 is an exchange, 13 is a telephone line, 14 is a terminal network control device, 15 is a meter, 16 is security equipment,
17 is a telephone.

The terminal network control device 14 is, as shown in FIG.
A main control unit 18 including a microcomputer having a ROM, a RAM, a CPU, and the like, a modem unit 19 for transmitting and receiving data to and from the center-side device 11, a local line unit 20 for transmitting data during communication, and power supply to each unit. Power supply unit 2
1, a meter interface (I / F) unit 22 for transmitting a signal from the meter 15 to the main control unit 18, and a security device interface (I / F) unit for transmitting a signal from the security device 16 to the main control unit 18. 23. V is a connection terminal to which a signal from the meter 15 is input, and S is a connection terminal to which a signal from the security device 16 is input.
2 and the security device I / F unit 23. The telephone line 13 is connected to a local line unit 20 and a modem unit 19 via a line terminal 13a, and the main control unit 18 is connected to a modem unit 19, a power supply unit 21, and a meter I / O.
The F unit 22 and the security device I / F unit 23 are connected, and the telephone set 17 is connected to the local line unit 20 via the telephone terminal 17a.
It is connected to the.

In the terminal network control device 14, gas,
A signal from a meter such as water supply or a security device is sent to the meter I / F section 22 and the security device I / F.
The data is received by the main control unit 18 via the F unit 23 and data communication is performed with the center apparatus 11 based on the signal.
The meter I / F unit 22 is, for example, the same as the conventional circuit of the Ministry of Posts and Telecommunications shown in FIG. 6 and transmits meter reading information from meters such as gas and water to the main control unit 18. .

As shown in FIG. 4, the security device 16 is a rescue button having a built-in switch (not shown), and is connected to connection terminals S1 and S2 of the terminal network control device 14 via a connection line 24. Have been. This is to notify the center that the emergency or abnormal situation has occurred to the user by activating the security device 16 by the user. That is, when the switch is turned on, an ON signal is input to the main control unit 18 via the security device I / F unit 23, and when the main control unit 18 determines that an abnormal situation has occurred, the information is transmitted to the main control unit 18. Communication is made from 18 to the center-side device 11. Further, a resistor Rs having a high resistance value (100 kΩ) is connected to the security device 16 in parallel. W1 and W2 are security devices 16
And a connection terminal for connection line 24.

The security device I / F 23 includes:
In order to perform the communication accurately and reliably, a connection state detecting unit 25 for detecting a connection state between the security device 16 and the I / F unit 23, and a self state detecting unit for detecting an internal state of the I / F unit 23 26.

The connection state detecting means 25 includes a resistor R82 provided in the security device 16 and having a value smaller than the resistor Rs and a resistor R8 having a value approximately twice as large as the resistor R82.
1 is provided. This is because the voltage between the resistors R81 and R82 and the resistor Rs on the security device side is divided by the security device 16 and the I / O.
This is for detecting whether or not the connection line 24 to the F section 23 is broken.

The disconnection detecting circuit 27, as shown in FIG.
NP transistor Tr6 and PNP transistor Tr
5, the collector terminal of the transistor Tr6 is connected to the connection terminal S1 via the resistor R82, and the emitter terminal is connected to the power supply Vcc. Transistor T
A power supply line r5 has a collector terminal connected to the intermediate point between the resistor R82 and the connection terminal S1 via the resistor R81 via the connection line 28, and an emitter terminal connected between the emitter terminal of the transistor Tr6 and the power supply Vcc. 29. The base terminals of the transistors Tr6 and Tr5 are connected to the ports P1 and P2 of the main control unit 18 via the resistors R87 and R88, respectively. R90 is connected.
A signal line 30 is provided between the resistor R81 and the connection line 28.
Is connected, and the other end of the signal line 30 is connected to the port P3 of the main control unit 18. A changeover switch 31 described later is interposed between the connection line 28 and the connection terminal S1, and the connection terminal S2 is grounded via a ground wire 32. When the transistor Tr6 and the transistor Tr5 are turned on and off, an L-level signal and an H-level signal are input to the port P3 of the main control unit 18, and the main control unit 18 determines whether the connection line 24 is disconnected based on the signal. Make a decision.

The self-state detecting means 26 is provided with a changeover switch 3 for separating the security device 16 from the I / F unit 23.
1 and an operation detection circuit 33 for detecting whether the I / F unit 23 operates normally. This is to perform a self-check of the I / F unit 23 in order to accurately transmit a signal from the security device 16 to the main control unit 18.

The change-over switch 31 is an electromagnetic relay. The electromagnetic relay 31 is used to perform the self-check of the I / F unit 23 so as not to be affected by the on / off state of the security device 16. This disconnects the connection line 28 from the connection terminal S1.

The operation detection circuit 33 includes an NPN transistor Tr7, and the collector terminal of the transistor Tr7 is connected to the connection line 28 via a resistor R83.
The emitter terminal is connected to the ground line 32 grounded to the ground, and the base terminal is connected to the main controller 1 via a resistor R91.
8 is connected to the port P4, and a resistor R92 is connected between the base and the emitter. The connection line 28 is connected in series with a changeover switch 35, a resistor R84 and a base terminal of the transistor Tr8, and a collector terminal of the transistor Tr8 has a signal connected to the port P5 of the main control unit 18 connected thereto. Line 34 is connected. When the transistors Tr7, Tr6, and Tr5 are turned on and off, the main control unit 18
L-level and H-level signals are input to ports P3 and P5 of the main control unit 18 based on the signals.
To determine whether the I / F unit 23 operates normally.

The security device I / F unit 23 supplies an intermittent power supply to the I / F unit 23 and detects an on / off state of the security device 16 when the power is supplied. Is provided. The on / off detection circuit 36 includes a transistor Tr9. The emitter terminal of the transistor Tr9 is connected to the ground line 32, the collector terminal is connected to the signal line 34 connected to the port P5 of the main control unit 18, and the base terminal is connected to a resistor. Table R9
3 is connected to the port P6 of the main control unit 18. A resistor R94 is connected between the base and the emitter of the transistor Tr9. This is to intermittently supply power to the I / F unit 23 to turn on / off the transistor Tr6, and then turn on the transistor Tr9 to set the port P5 of the main control unit 18 to L level to permit hardware interrupts. Then, the on / off state is determined softly by detecting the rise of the port P5 of the main controller 18 from the L level to the H level.

Further, the security device I / F unit 23
NP for matching with the meter I / F unit 22
An N transistor Tr8, a transistor Tr7 and a resistor R83 are provided. The transistor Tr8 is
Its base terminal is connected to a resistor R84 and a changeover switch 35.
, The collector terminal is connected to the port P5 of the main control unit 18, and the emitter terminal is connected to the ground line 32. A resistor R86 is interposed between the power supply line 29 and the midpoint between the collector terminal of the transistor Tr8 and the port P5 of the main control unit 18, and a resistor R85 is connected between the base and the emitter of the transistor Tr8. I have. This is because the resistor R83 is connected to the meter I / F.
The transistor Tr is set to a value that can be shared with the unit 22.
8. By using the resistor R84, the resistor R85, and the resistor R86, the input logic to the main control unit 18 is reversed and the impedance is matched, so that the meter I / F unit 22 and the security device I / F unit 23 are connected. They are shared. That is, as compared with the security device I / F unit 23 and the meter I / F unit 22 shown in FIG. 6, the transistors Tr1, Tr6, and Tr2
Transistor Tr7, transistor Tr3 and transistor Tr8, resistor R61 and resistor R82, resistor R6
2, resistor R83, resistor R63 and resistor R84, resistor R64 and resistor R85, resistor R65 and resistor R86
Correspond to each other, so that the security device I / F unit 23 can be used as the meter I / F unit 22 by controlling each unit. In this case, the meter 15 is connected to the ground line 32 via the connection line and the connection terminal S.
1 and the electromagnetic relay 31. Therefore,
The need for the meter I / F section 22 is eliminated, so that the cost can be reduced by reducing the number of parts and the size of the apparatus can be reduced. Note that the changeover switch 35 is an electromagnetic relay, and in order to eliminate the influence of the impedance of the transistor Tr8, the resistor R84, and the resistor R85 when detecting the connection state between the security device and the I / F unit 23. In addition, the disconnection detection circuit 27 and the transistor Tr8 are separated.

In the above configuration, the security device 16
When detecting the connection state between the I / F unit and the I / F unit 23, first, the main control unit 18 turns off the electromagnetic relay 35 to disconnect the transistor Tr8 from the disconnection detection circuit 27, and turns on the electromagnetic relay 31 to turn on the I / F unit. Unit 23 and security device 1
6 is connected. Then, when the transistor Tr6 is turned on, a current from the power supply Vcc is supplied to the security device 16 from the connection terminal S1 via the resistor R82. At this time, when the point F of the connection line 28 shown in FIG. 1 becomes the H level due to the voltage division between the resistor R82 and the resistor Rs of the security device 16, the port P3 of the main control unit 18 becomes H level via the signal line 30. The level signal is input, and the main control unit 18 determines that the security device 16 is off. On the other hand, the resistor R82 and the resistor Rs of the security device 16
When the point F of the connection line 28 becomes L level due to the partial pressure of
An L-level signal is input to the port P3 of the main control unit 18, and it is determined that the security device 16 is on. This is because the security device 16 and the I / F unit 23
Indicates that the connection line 24 is not disconnected.

Next, when the transistor Tr6 is turned off and the transistor Tr5 is turned on, a current is supplied from the connection terminal S1 to the security device 16 via the resistor R81. At this time, if the security device 16 is off, the resistor R81 and the resistor R
The point F of the connection line 28 becomes L level due to the partial pressure with s.
Therefore, an L-level signal is input to the port P3 of the main control unit 18, and the main control unit 18 determines that the connection line 24 between the I / F unit 23 and the security device 16 is not disconnected. At this time, the port P3 of the main control
When the level signal is input, it is determined that the connection line 24 is disconnected. On the other hand, when the security device 16 is in the ON state, the voltage of the resistor R81 and the resistor Rs of the security device 16 causes the point F of the connection line 28 to go to the H level, and the port P3 of the main control unit 18 to the H level. The level signal is input, and it is determined that the connection line 24 is not disconnected.
At this time, when an L-level signal is input to the port P3 of the main control unit 18, it is determined that the connection line 24 is disconnected. Then, the security device 16 and the I / F unit 23
When it is detected that the connection line 24 is disconnected, the main controller 18 notifies the center side device 11 of the information.

When performing a self-check of the security device I / F unit 23, first, the main control unit 18 turns on the electromagnetic relay 35 to turn on the connection line 28 and the transistor Tr.
8 and the electromagnetic relay 31 is turned off to disconnect the security device 16 from the I / F unit 23. Then, when the transistor Tr6 is turned on, the current passes through the resistor R82, the electromagnetic relay 35, and the resistor R84, and the transistor Tr8 is turned on. As a result, an L-level signal is input to the port P5 of the main control unit 18. When the input signal is confirmed and the transistor Tr6 is turned off and the transistor Tr5 is turned on, an L-level signal is input to the port P5 of the main control unit 18. Next, when the transistor Tr7 is turned on, the point F of the connection line 28 becomes L level, and an H level signal is input to the port P5 of the main control unit 18.

As a result of this series of operations, if all the signals input to the port P5 of the main control unit 18 can be confirmed as described above, the security device I / F unit 23 is determined to be normal. If a signal different from the above is input to the port P5 of the main control unit 18, it is determined that an abnormality has occurred in the I / F unit 23, and the information is transmitted to the center-side device 11.
Inform When the self-check is completed, the electromagnetic relay 31 is turned on and the security device 16 and the I / O
F section 23 is connected.

To detect the on / off state of the security device 16, the main controller 18 turns on the electromagnetic relays 31 and 35, respectively. Then, the transistor Tr5 and the transistor Tr6 are periodically turned on and off, and intermittent power supply to the I / F unit 23 is performed. At this time, if the security device 16 is in the ON state, the current flows from the transistors Tr5 and Tr6 to the ground via the connection terminal S1, the security device 16, and the connection terminal S2. Regardless of the on / off state of the Trs 5 and 6, the port P3 of the main control unit 18 is at the L level and the port P5 is at the H level.
The level signal is input, and it is determined that the security device 16 is on.

When the security device 16 is turned off from on, the H level signal is input to the port P3 and the L level signal is input to the port P5 of the main control unit 18 by the resistor R82 at the same time when the transistor Tr6 is turned on. As a result, when the port P5 of the main control unit 18 falls from the H level to the L level (point M in FIG. 5), it is determined that the security device 16 has been turned off from on. But I
Since the / F section 23 is intermittently supplied with power in order to reduce current consumption, when the security device 16 is in the off state, the transistor Tr6 is turned on and off as shown in section B in FIG. , The signals of the L level and the H level are alternately input to the port P3 and the port P5, so that the on / off state of the security device 16 cannot be determined.

To detect the security device 16 from off to on, the transistor Tr9 is turned on shortly before the transistor Tr6 is turned on (time Ts in FIG. 5), and the input signal to the port P5 of the main controller 18 is turned on. Is set to the L level, and a hardware interrupt is permitted so that the rise of the port P5 from the L level to the H level can be detected.
Next, the transistor Tr6 is turned on, and after a short time (time Tu in FIG. 5), the transistor Tr9 is turned off. At this time, if the security device 16 is off, the port P5 of the main control unit 18 remains at the L level, no interrupt occurs, and it is determined that the security device 16 is kept off. It changes to the H level at the same time when Tr6 is turned off. On the other hand, if the security device 16 is in the ON state, the port P5 of the main control unit 18 rises to the H level simultaneously with the turning off of the transistor Tr9 (point I in FIG. 5). At this time, a hardware interrupt is generated, and the rise of the port P5 from L level to H level is detected, and it is determined that the security device 16 is on. If the security device 16 is on, the emergency button is pressed due to the occurrence of an abnormal situation, and the information is transmitted from the main control unit 18 to the center device 11.

By providing the connection state detecting means 25 and the self state detecting means 26 as described above, one I
Since the connection state between the security device 16 and the I / F section 23 and the self-check of the I / F section 23 can be easily performed by the / F section 23, the connection state can be detected as in the conventional I / F section. However, there is no problem that a self-check cannot be performed or a self-check can be performed but a connection state cannot be detected.

The security device 16 is provided with a resistor Rs having a high resistance value, and the disconnection detection circuit 27 is provided with a resistor R82 having a value smaller than the resistor Rs and a resistor R81 having a value approximately twice as large as the resistor R82. Therefore, whether the security device 16 is off or the connection line 24 to the I / F unit 23 is disconnected is determined by the voltage division between the resistor Rs of the security device 16 and the resistors R81 and R82. Can be detected. Moreover, the resistors Rs, R81, R
Since the disconnection can be detected by a simple method only by providing the 82, provision of the inexpensive I / F unit 23 can be realized.

When the self-check of the I / F unit 23 is performed, the security device 16 and the I / F unit 23 are separated by the electromagnetic relay 31, so that the security device 16 is affected by the on / off state. Without
A reliable self-check can be performed. Therefore, the maintenance is performed by communicating to the center side quickly without overlooking the abnormality of the I / F unit 23. Therefore, even if a security device with a high urgency is connected, the I / F unit 23 is in communication.
Does not malfunction or does not operate, and high reliability is obtained as a data communication system.

Further, when the on / off state of the security device 16 is to be detected, the same operation as when the power is constantly supplied by the on / off detection circuit 36 is obtained even if the power is intermittently supplied to the I / F unit 23. Since the interruption is permitted to perform the processing, the on / off state of the security device 16 can be detected based on the presence or absence of the interruption. Therefore, if intermittent power supply is performed as in the related art, it is not impossible to detect the on / off state, and the processing can be easily performed by software.

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. For example, in the above embodiment, an electromagnetic relay is used as the changeover switch 35, but a semiconductor switch such as a transistor or a gate may be used.

Although the security apparatus I / F section 23 has been described in the above embodiment, the security apparatus I / F section 22 may be used. Further, the connection state detecting means 25 and the self state detecting means 26 are provided in both the I / F sections 22 and 23 for the meter and the security device, and the meter 15 and the security apparatus 16 communicate with the both I / F sections 22 and 23. If the connection is made possible, even if one of the I / F units is in a communication-disabled state due to disconnection or failure, both the meter 15 and the security device 16 can communicate with the other I / F unit. Therefore, the reliability of the device can be further improved.

[0047]

As is apparent from the above description, according to the first aspect of the present invention, by providing the connection state detecting means and the self state detecting means, the connection state between the terminal device and the interface section can be controlled by one interface section. Detection,
Since the self-check in the interface unit can be easily performed, there is no problem that the connection state can be detected but the self-check cannot be performed as in the conventional interface unit, or the self-check can be performed but the connection state cannot be detected.

According to the second aspect of the present invention, the terminal device is provided with a resistor, and the disconnection detection circuit is provided with a resistor having a value different from that of the terminal device. Therefore, the resistor of the terminal device and the resistor of the disconnection detection circuit are provided. It is possible to detect whether the terminal device is in the off state or the connection line with the interface unit is in the disconnected state. In addition, disconnection can be detected by a simple method of simply providing a resistor, so that an inexpensive I / F can be provided.

According to the third aspect, when the self-check of the interface unit is performed, the terminal device and the interface unit are separated by the changeover switch, so that the self-check is not affected by the on / off state of the terminal device.
A reliable self-check can be performed. Therefore, maintenance is performed by communicating quickly to the center side without overlooking the abnormality of the interface unit, and even if a highly urgent security device is connected, the interface unit may malfunction or not operate during communication. High reliability can be obtained as a data communication system without causing any trouble.

According to the fourth aspect, by sharing the interface section for the meter and the security device, one of the interface sections becomes unnecessary, so that the cost can be reduced by reducing the number of parts and the size of the apparatus can be reduced.

According to the fifth aspect, when the on / off state of the terminal device is detected, the same processing as when the power is constantly supplied by the on / off detection circuit is performed even if the power supply is intermittently supplied to the interface unit. Since the interruption is permitted to perform the operation, the on / off state of the terminal device can be detected based on the presence or absence of the interruption. Therefore, an intermittent power supply as in the related art does not make it impossible to detect the on / off state, and has an excellent effect that processing in software is simplified.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an I / F unit for a security device of a terminal network control device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a data communication system including a terminal network control device.

FIG. 3 is a block diagram of a terminal network control device.

FIG. 4 is a configuration diagram of a security device.

FIG. 5 is a timing chart showing an on / off detection operation of the security device.

FIG. 6 is a circuit diagram of a conventional meter I / F unit.

FIG. 7 is a circuit diagram of a conventional security device I / F unit.

[Explanation of symbols]

 Reference Signs List 11 center-side device 13 telephone line 15 meter 16 security device 18 main control unit 23 security device I / F unit 25 connection state detection means 26 self-state detection means 27 disconnection detection circuit 31 electromagnetic relay 33 operation detection circuit 36 on / off detection circuit Rs Resistor for security equipment R81, 82 Resistor for disconnection detection circuit

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-60564 (JP, A) JP-A-62-35747 (JP, A) JP-A-59-195788 (JP, A) JP-A 52-357 132798 (JP, A) JP-A-2-31298 (JP, A) JP-A-62-164362 (JP, A) JP-A-61-42098 (JP, A) JP-A-59-68095 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H04M 11/00-11/10

Claims (5)

(57) [Claims] 1. A terminal device such as a meter or a security device is connected, and data communication with a center device is performed by a main control unit via an interface unit based on a signal from the terminal device using a telephone line. in the terminal network control unit for, upon detecting a connection state between the terminal equipment and the interface unit based on a signal from the main control unit
Both have a connection state detecting means for detecting the on / off state of the terminal device, and a self-state detecting means for detecting the internal state of the interface unit by disconnecting the terminal device. Terminal network controller. 2. A connecting state detection means comprises a plurality of resistors of the resistor value different provided in the terminal device, the terminal device by each of the partial pressures of the resistor of the terminal device and each resistor connection line between the interface unit is not broken and the
2. The terminal network control device according to claim 1, further comprising a disconnection detection circuit that detects whether the terminal device is in an off state or not . 3. A self-state detecting means, comprising: a changeover switch for separating an interface unit from a terminal device;
2. The terminal network control device according to claim 1, further comprising an operation detection circuit for detecting whether or not the interface unit operates normally after disconnecting the device from the interface unit . 4. The input logic is reversed to share an interface section for a meter and a security device.
With a circuit to match the impedance
Terminal network controller according to claim 1, 2 or 3, wherein it was. 5. An on / off detection circuit for intermittently supplying power to an interface unit and detecting an on / off state of a terminal device when power is supplied. Alternatively, the terminal network control device according to 4.