JPH04313942A - Network controller for non ringing communication - Google Patents

Abstract

PURPOSE:To easily detect a polarity inversion even when a network controller and a telephone line are connected with the polarity of the both set reverse and to attain the succeeding operation by providing a switch able to reverse the connection polarity of the network controller and the telephone line. CONSTITUTION:A connection section between telephone lines L1, L2 and the network controller is provided with a changeover switch SW2 reversing the connection polarity of the telephone lines L1, L2 and a control section 6 reversing the connection of the telephone lines L1, L2 via the changeover switch SW2 when the polarity inversion is detected in the standby state. That is, when the reversed polarity connection is judged, the switch SW2 is inverted (set from 'a' to 'b') to set the standby state. The polarity is restored when a terminal L1 is set to -48V and a terminal L2 is set to ground 0V by reversing the switch SW2, and the polarity inversion is detected when the terminal L1 is set to ground and the terminal L2 is set to -48V. Thus, even when the polarity connection is reversed, the controller is operated to avoid defect communication due to the reverse connection.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is applicable to automatic meter reading systems using NTT no-ringing communication services, etc.
(Meter) Regarding terminal side network control equipment. Note that in the following figures, the same reference numerals indicate the same or corresponding parts.

0002

2. Description of the Related Art FIG. 4 shows an example of the configuration of a conventional terminal-side network control device. In the same figure, L1 and L2 are telephone line connection terminals,
1 is an incoming signal detection circuit, 2 is a polarity reversal detection circuit, 3 is a loop detection circuit, 4 is a line termination circuit, 5 is a signal transmission/reception unit,
6 is a control section, D1 and D2 are diodes, and SW1 is a switch. Here, the incoming signal detection circuit 1 is a circuit that detects an incoming signal (75 Vrms, 16 Hz) when a telephone call is received. The polarity reversal detection circuit 2 is a circuit that detects that the polarity of the telephone line has been reversed. The loop detection circuit 3 is a circuit that detects when a closed loop is formed by the telephone line and the network control device and a direct current flows. The line termination circuit 4 is a circuit for passing a direct current when a closed loop is formed between the telephone line and the network control device. The signal transmitting/receiving section 5 receives a no-ringing paging signal (NRS), transmits a no-ringing response signal, and transmits/receives a data signal. The diodes D1 and D2 and the switch SW1 are a circuit for closing the switch SW1 and allowing a direct current to flow when polarity reversal is detected. The NTT no-ringing communication service performs a no-ringing call to a terminal-side network control device by inverting the polarity of the telephone line and sending out a no-ringing call signal (NRS). The telephone line consists of two lines, L1 line and L2 line, and the polarity of the telephone line is normal (when the polarity is restored).
, L1 line: earth (0V), L2 line: -48V.

As shown in FIG. 4, the network control device has an L1 terminal and an L2 terminal as telephone connection terminals, and when connecting the telephone line and the network control device, the L1 line and the L1 terminal, and the L2 line and the L2 terminal are connected. do. In this case, under normal conditions, L1 terminal: Earth (0V), L2 terminal: -48V, and when polarity is reversed, L1 terminal: -48V, L2
Terminal: Ground (0V). Therefore, when the control section 6 detects the reversal of the polarity of the telephone line by the polarity reversal detection circuit 2, it turns on the switch SW1. When switch SW1 is turned on, diode D1
, switch SW1, loop detection circuit 3, line termination circuit 4
, a current flows from the L2 terminal to the L1 terminal through the diode D2. Thereafter, the signal transmitting/receiving section 5 receives a no-ringing call signal and enters a no-ringing communication state. When the no-ringing communication ends, the polarity of the telephone line is restored (L1 terminal: ground (0V), L2 terminal: -
48V), current stops flowing. As a result, the signal from the loop detection circuit 3 is turned off, so the control section 6 turns off the switch SW1 and returns to the standby state. As described above, in the conventional network control device, the circuit was energized and operated only when the polarity was reversed.

0004

SUMMARY OF THE INVENTION In order to receive a no-ringing call, it is necessary to detect the polarity reversal of the telephone line. In the conventional terminal-side network control device, polarity reversal is detected by a dedicated polarity reversal detection circuit 2. but,
This network control device has high resistance except when a call is received, and no current should be allowed to flow through it. Therefore, polarity reversal and recovery must be monitored without flowing direct current, which requires a complex circuit to detect polarity reversal. In addition, with conventional network control equipment, when connecting the telephone line and network control equipment,
When connecting the L1 line and the L2 terminal, and the L2 line and the L1 terminal, under normal conditions L1 terminal: -48V,
L2 terminal: Earth (0V) When polarity is reversed L1 terminal: Earth (0V), L2 terminal:
-48V, and the network control device detects polarity reversal during normal times and detects polarity recovery when polarity is reversed, making communication impossible. Therefore, when connecting a telephone line and a network control device, it is inconvenient to check the polarity of the telephone line before making the connection. Therefore, an object of the invention according to claim 1 is to provide a network control device for no-ringing communication that can operate even if the polarity is reversed when connecting the telephone line and the network control device. Further, the problem of the invention related to claims 2 to 4 is to eliminate a dedicated polarity reversal detection circuit from the network control device, and to provide no-ringing communication that can operate even if the polarity is reversed when connecting the telephone line and the network control device. The purpose of this invention is to provide a network control device.

[0005]

[Means for Solving the Problems] In order to solve the above problems, a network control device according to a first aspect of the present invention provides a telephone line (L1, L2
polarity reversal detection means (polarity reversal detection circuit 2, etc.) that detects that the polarity of the voltage of the telephone line (such as the polarity reversal detection circuit 2) has become an inverted polarity for making a call or communication; A current loop is configured by connecting a detection means (such as an incoming signal detection circuit 1), a no-ringing transmitting/receiving means (such as a signal transmitting/receiving section 5), and the telephone line based on the detection of the inverted polarity and the absence of the incoming signal. A network control device for no-ringing communication equipped with an on-off switch (SW1, etc.) for switching, a changeover switch (SW2, etc.) capable of reversing the connection polarity of the telephone line at a connection portion between the telephone line and the network control device; and means (control unit 6, etc.) for reversing the connection of the telephone line via the changeover switch when the reversed polarity is detected during standby;

[0006] The network control device according to claim 2 is a switch that opens and closes a current loop connecting a telephone line and a no-ringing transmitting/receiving means (signal transmitting/receiving unit 5, etc.), and the switch corresponds to the two polarities of the telephone line. two switches (SW11, SW12, etc.) that are provided to supply electricity of the same polarity to the no-ringing transmitting/receiving means; a loop detecting means (loop detecting circuit 3, etc.) that detects energization to the no-ringing transmitting/receiving means; an incoming signal detection means (incoming signal detection circuit 1, etc.) for detecting an incoming signal for a telephone call from a telephone line, and one of the two switches on which the loop detection means does not detect the energization during standby. means (control unit 6, etc.) for closing the switch and causing the no-ringing transmitting/receiving means to perform a transmitting/receiving operation based on the detection of energization of the loop detecting means and the detection of the absence of the incoming signal in the closed circuit state. and

[0007] The network control device according to claim 3 is the network control device according to claim 2, when it is determined by the transmission/reception operation of the no-ringing transmission/reception means that the communication is directed to another network control device. means (control unit 6, etc.) that opens the switch that is currently in a closed state, closes the other switch, and returns the switch to the closed state during standby based on the energization detection of the loop detection means in this state.
shall be equipped with

In the network control device according to claim 4, the network control device according to claim 2 or 3 includes a single-phase bridge-connected diode bridge consisting of four diode arms (diodes D11 to D14, etc.), The telephone line is connected to the AC side terminal of this bridge, the DC side terminal of this bridge is connected to the polarity that causes the no-ringing transmitting/receiving means to conduct the electricity, and the two switches are connected to the DC side positive terminal of this diode bridge. between one cathode and the other cathode of the two diode arms that constitute the diode bridge, and between one anode and the other anode of the other two diode arms that constitute the DC side negative terminal of the diode bridge, respectively. Make sure it is inserted.

[0009]

[Function] (1) Regarding the invention related to claim 1: A changeover switch for reversing the connection with the telephone line is attached to the connection between the network control device and the telephone line, and by reversing this changeover switch, Even if the polarity of the telephone line and the network control device are reversed, the polarity reversal can be detected and subsequent operations can be performed. (2) Regarding the inventions related to claims 2 to 4: A circuit for controlling the current direction of the telephone line connection terminal is attached to the network control device by combining a diode and a switch element, and when the polarity of the telephone line is in the restored state, the telephone line Set the current direction of the connection terminal so that the current flows with the polarity reversed. In this way, when the polarity of the telephone line is reversed, a current flows, so that the loop detection circuit can detect the polarity reversal. Further, once the no-ringing communication state is entered, if another network control device is called, the current direction is switched and set so that the current flows in the polarity recovery state. In this way, when the polarity of the telephone line is restored, a current flows, so that the loop detection circuit can detect the polarity restoration. It also detects the polarity reversal of the telephone line, 1)
No-rigging incoming call 2) Incoming telephone call 3) Determine if the polarities of the telephone line and network control device are reversely connected, and if the polarities of the telephone line and network control device are reversely connected, reverse the current direction of the telephone line connection terminal.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the configuration of a network control device as an embodiment of the invention according to claim 1, and corresponds to FIG. In FIG. 1, as in FIG. 4, an incoming signal detection circuit 1, a polarity reversal detection circuit 2, a loop detection circuit 3, a line termination circuit 4, a signal transmission/reception section 5, a control section 6, diodes D1, D2, and a switch SW1 are provided. In addition, a new switch SW2 has been added. Here, the switch SW2 reverses the connection with the telephone line. When the switch SW2 is set in the a direction, the direction in which current can be passed in the circuit shown in Figure 1 is from the L2 terminal to the L1 terminal, and the polarity reversal detection circuit 2 is as follows: L1 terminal: earth (0V), L2 terminal: polarity when -48V Restoration state (power cannot be supplied) L1 terminal: -48V, L2 terminal: Earth (
0V), the polarity reversal state (current can be applied) is detected. When switch SW2 is set in direction b,
The direction in which current can be passed is from the L1 terminal to the L2 terminal, and the polarity reversal detection circuit 2 has the following conditions: L1 terminal: -48V, L2 terminal: Earth
0V), detects the polarity recovery state (current cannot be applied).L1 terminal: Earth (0V), L2 terminal: detects the polarity reversal state (current can be applied) when -48V.

It is now assumed that the network control device is in a standby state and the switch SW2 is set in the a direction. The operation of the network control equipment in this state is
Incoming calls and reversing the polarity of the telephone line and network control equipment will be explained. (1) No-ringing incoming call: When the polarity of the telephone line is reversed, the polarity reversal detection circuit 2 detects the polarity reversal. When the polarity reversal is detected, the control unit 6 turns on the switch SW1 to enter a no-ringing call signal reception state. When the signal transmitting/receiving unit 5 receives a no-ringing call signal and the signal is a call to its own terminal, a no-ringing communication state is established. When the no-ringing communication is completed, the polarity of the telephone line is restored, so that no current flows, and the signal from the loop detection circuit 3 is turned off, so that the control unit 6 returns to the standby state. If the no-ringing call signal is a call to another network control device, the switch SW1 is turned off to enter a standby state.

(2) Incoming telephone call: When the polarity of the telephone line is reversed, the polarity reversal detection circuit 2 detects the polarity reversal. When the polarity reversal is detected, the switch SW1 is turned on to enter a no-ringing call signal reception state. After the polarity reversal is detected, the incoming signal detection circuit 1 detects an incoming signal without receiving a no-ringing call signal. When an incoming signal is detected, the control unit 6 turns off the switch SW1 and waits for the incoming signal to end. When the incoming signal ends, it enters a standby state.

(3) Reverse polarity connection between telephone line and network control device: If the polarity is reversed when connecting the telephone line and network control device, when the polarity is restored, L1 terminal: -48V, L2
Terminal: Earth (0V) When polarity is reversed L1 terminal: Earth (0V), L2 terminal:
-48V. In the network control device, the switch SW2 is set in the a direction so that the polarity reversal is detected with the L1 terminal: -48V and the L2 terminal: ground (0V), so the polarity reversal is detected with the polarity reversal detection circuit 2. , since it is not possible to receive a no-ringing call signal or detect an incoming signal after that.
It can be determined that the polarity of the telephone line and network control device are reversed. If it is determined that the polarity is reversed due to reverse connection, switch SW2
is reversed (switch SW2 is set in the b direction) to enter a standby state. By reversing the switch SW2 in this way (setting the switch SW2 in the b direction), the L1 terminal:
-48V, L2 terminal: Polarity recovery state when the L2 terminal is grounded (0V). Polarity reversal state will be detected when the L1 terminal: grounded (0V), L2 terminal is -48V, so if the polarity is connected in reverse. However, it is possible to operate.

Next, FIG. 2 shows the configuration of a network control device as an embodiment of the invention according to claims 2 to 4. In the same figure, the polarity reversal detection circuit 2 is omitted compared to FIG.
A circuit consisting of 2 is added. This diode D1
1 to D14 and the switches SW11 and SW12 are circuits that turn on and off the switches SW11 and SW12 to control the direction of direct current flowing through the network control device as seen from the telephone line side. In FIG. 2, when switch SW11 is turned off and switch SW12 is turned on, the current direction is L2.
The direction is from the terminal to the L1 terminal, L1 terminal: -1
4V, L2 terminal: When grounded (0V), DC current flows through diode D12, loop detection circuit 3, line termination circuit 4, switch SW12, and diode D13. Conversely, when switch SW11 is turned on and switch SW12 is turned off, the direction in which current can be passed is from the L1 terminal to the L1 terminal, and the L1 terminal: earth (0V), L
2nd terminal: When the voltage is -48V, a direct current flows through the diode D11, switch SW11, loop detection circuit 3, line termination circuit 4, and diode D14. Currently, the network control device is in a standby state, switch SW11 is off, switch SW12 is on, and when the L1 terminal is grounded (0V) and the L2 terminal is -48V, the polarity recovery state (
(Not energized) L1 terminal: -48V, L2 terminal: Earth (
0V), the loop detection circuit 3 detects the polarity inversion state (energization).

Next, the operation of the network control device in this state will be explained with reference to the operation flowchart of FIG. 3 for each of no-ringing call reception, telephone call reception, and reverse polarity connection between the telephone line and the network control device. Note that hereinafter, symbols S1 to S8 indicate steps in FIG. (1) No-ringing incoming call: When the polarity of the telephone line is reversed, a direct current flows and the loop detection circuit 3 is turned on, detecting that the polarity has been reversed (S1). By detecting this polarity reversal, a no-ringing call signal reception state is entered. When the signal transmitting/receiving unit 5 receives a no-ringing call signal (S2) and it is a call to its own terminal (S3)
, a no-ringing communication state (S4) is entered. When the no-ringing communication ends, the polarity of the telephone line is restored, so
Current stops flowing. Since the signal from the loop detection circuit 2 is turned off, the system returns to the standby state. If the no-ringing call signal is a call to another network control device, turn on switch SW11 and turn off switch SW12.
Reverse the current direction so that DC current flows when the polarity is restored. When the polarity of the telephone line is restored, a direct current flows and the loop detection circuit 3 is turned on, detecting that the polarity of the telephone line has been restored (S7). If polarity recovery is detected,
The switch SW11 is turned off and the switch SW12 is turned on to return the current direction to the original state and enter a standby state.

(2) Incoming telephone call: When the polarity of the telephone line is reversed, a direct current flows and the loop detection circuit 3 is turned on, detecting that the polarity has been reversed (S1). Upon detection of polarity reversal, a no-ringing call signal reception state is entered. After the polarity reversal is detected, no no-ringing call signal is received (S2), and the incoming signal detection circuit 1 detects an incoming signal (S5). When an incoming signal is detected, the switches SW11 and SW12 are turned off and the process waits for the incoming signal to end (S6). When the incoming signal ends, switch SW
11 is turned on, switch SW12 is turned off, and the switch is set in the direction in which the current flows when the polarity is restored. When the polarity is restored, DC current flows, so loop detection circuit 3
It is possible to detect that a closed loop has been formed and that the polarity of the telephone line has been restored (S7). When polarity recovery is detected, switch SW11 is turned off and switch SW1 is turned off.
2 is turned on, the energization direction is returned to the original state, and the device enters a standby state.

(3) Reverse polarity connection between the telephone line and the network control device: If the polarity is reversed when connecting the telephone line and the network control device, under normal conditions (when the polarity is restored), the L1 terminal:
-48V, L2 terminal: Earth (0V), L when polarity is reversed
1 terminal: Earth (0V), L2 terminal: -48V. In this network control device, in a standby state, switch SW11 is turned off and switch SW12 is turned off so that the voltage of the telephone line connection terminals is L1 terminal: -48V, L2 terminal: ground (0V), and a current flows to detect polarity reversal. is set to be on by default. If the polarity of the telephone line and network control device are reversed, normal operation (when polarity is restored) will occur.
However, L1 terminal: -48V, L2 terminal: Earth (0
V), current flows and polarity reversal is detected (S1
), followed by reception of a no-ringing call signal (S2
), nor can an incoming signal be detected (S5), so it can be determined that the polarities of the telephone line and network control device are reversely connected. If it is determined that the polarity has been reversed due to reverse connection, the current direction of the telephone line connection terminal is reversed (switch SW11 is turned on and switch SW12 is turned off) (S8), and a standby state is entered. The subsequent operation is an operation in which switch SW1 and switch SW2 in the above operation description are exchanged, and the L1 terminal: -
When the voltage is 48V, the L2 terminal is grounded (0V), the polarity is restored; the L1 terminal is grounded (0V), and the L2 terminal is -48V, the polarity inverted state is detected.

[0018]

Effects of the Invention According to the invention related to claim 1, when connecting a telephone line and a network control device, it is possible to operate even if the polarity is reversed. can be eliminated. According to the inventions according to claims 2 to 4, polarity reversal and restoration are detected by controlling the current direction of the telephone line connection terminal and by the loop detection circuit, so that a dedicated polarity reversal detection circuit is not required. In addition, when connecting the telephone line and the network control device, it is now possible to operate even if the polarity is reversed, so there is no communication failure caused by reverse connection as in the past, so please check the polarity of the telephone line before connecting. There is no need to do so.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a network control device as an embodiment of the invention according to claim 1.

FIG. 2 is a block diagram showing the configuration of a network control device as an embodiment of the invention according to claims 2 to 4.

[Figure 3] Flowchart for explaining the operation of Figure 2

[Figure 4] Block diagram showing the configuration of a conventional network control device

[Explanation of symbols]

1 Incoming signal detection circuit 2 Polarity reversal detection circuit 3 Loop detection circuit 4 Line termination circuit 5 Signal transmitting and receiving section 6 Control section D1 Diode D2 Diode D11~D14 Diode SW1 switch SW2 switch SW11 Switch SW12 switch L1　Telephone line connection terminal L2 Telephone line connection terminal

Claims (4)

[Claims] 1. A polarity reversal detection means for detecting that the polarity of the voltage of a telephone line has become an inverted polarity for a telephone call or communication; an incoming signal detection means for detecting an incoming signal for a telephone call from the telephone line; A no-ringing communication network control device comprising an opening/closing switch that connects a no-ringing transmitting/receiving means and the telephone line to form a current loop based on the detection of the inverted polarity and the absence of the incoming signal. A changeover switch capable of reversing the connection polarity of the telephone line at a connection portion with the network control device; and means for reversing the connection of the telephone line via the changeover switch when the reversed polarity is detected during standby. A network control device for no-ringing communication, characterized by comprising: 2. A switch for opening and closing a current loop connecting a telephone line and a no-ringing transmitting/receiving means, the switch being provided corresponding to two polarities of the telephone line, and configured to supply current of the same polarity to the no-ringing transmitting/receiving means. loop detecting means for detecting energization of the no-ringing transmitting/receiving means; incoming signal detecting means for detecting an incoming signal for a call from the telephone line; The loop detecting means closes the switch on the side where the energization is not detected, and the no-ringing transmitting/receiving means operates based on the detection of the energization of the loop detecting means and the detection of the absence of the incoming signal in this closed state. 1. A network control device for no-ringing communication, comprising means for performing transmission and reception operations. 3. In the network control device according to claim 2, when it is determined by the transmission/reception operation of the no-ringing transmitting/receiving means that the communication in question is directed to another network control device, the network control device which is currently in a closed circuit state A network control device for no-ringing communication, comprising means for opening a switch, closing the other switch, and returning the switch to the closed circuit during standby based on the energization detection of the loop detection means in this state. . 4. A network control device according to claim 2 or 3, comprising a single-phase bridge-connected diode bridge consisting of four diode arms, the telephone line being connected to an AC side terminal of the bridge, The DC side terminal of this bridge is connected to the polarity that causes the no-ringing transmitting/receiving means to conduct the current, and the two switches are connected to one cathode and the other of two diode arms constituting the DC side positive terminal of this diode bridge. For no-ringing communication, characterized in that the device is inserted between the cathode and between one anode and the other anode of two other diode arms constituting the DC-side negative terminal of the diode bridge. Network control device.