JPH0297158A - Malfunction restoring system for subscriber line test lead-in switch - Google Patents

Abstract

PURPOSE:To display the malfunction of a subscriber line test lead-in switch to a host controller by comparing the potential of a subscriber line test lead-in wire with a prescribed voltage, detecting the malfunction condition of the subscriber line test lead-in switch and controlling the stop of feeding to a switch circuit and a feeding circuit. CONSTITUTION:The voltage of lead-in wires 9 and 10, with which subscriber lines 2 and 3 are tested for a subscriber line test lead-in switch malfunction detecting and restoring circuit 8, and a prescribed voltage (Vref) to be obtained by a reference voltage source 83 are compared by comparators 81 and 82. Thus, the malfunction condition of the subscriber line test lead-in switch 6 is detected by an OR gate 86 and held by using a latch circuit 87. At such a time, the latch circuit 87 outputs a MSLT signal to a switch circuit 4 and a feeding circuit 5. The MSLT signal controls the stop of feeding and executes the malfunction detection display of the subscriber line test lead-in switch 6 to the host controller.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a subscriber circuit of a telephone exchange, and more particularly to a malfunction recovery method for a subscriber line test lead-in switch.

(Prior art) Conventionally, to prevent malfunction of subscriber line test lead-in switches, the voltage change tolerance over one hour, that is, dv/
A method using a PNPN element with high dt tolerance has been known.

(Problem where the invention is about to disappear) In the conventional subscriber line test lead-in switch mentioned above, the dv
The false ignition characteristic is fully specified as /dt tolerance, and a PNPN switch element with high dv/dj tolerance is adopted to prevent false ignition from occurring due to sudden voltage changes occurring on the terminal side.

However, considering sudden voltage changes that occur on the terminal side, such as lightning surges or other DV/DT's, the subscriber line test lead-in switch may be able to withstand the DV/DI current level. There is a drawback in that it is not possible to completely prevent malfunctions of the subscriber line test drop-in switch due to erroneous pulses such as noise generated in the line test drop-in switch drive signal.

Furthermore, once the PNPN switch is erroneously fired, the current will continue to flow through the subscriber circuit's power supply circuit to maintain the erroneously ignited state because it has a current holding function.
It has the disadvantage of interfering with the normal operation of subscriber circuits.

The purpose of the present invention is to compare the voltage of the subscriber line test drop-in line with a predetermined voltage, detect and maintain all conditions of malfunction of the subscriber line test drop-in switch, control the power supply to the power supply circuit to be stopped, and control the power supply to the power supply circuit. A malfunction of the subscriber line test drop-in switch configured to eliminate the above-mentioned drawbacks and not interfere with the normal operation of the subscriber circuit by displaying a malfunction detection display of the subscriber line test drop-in switch to the control device. The goal is to provide a recovery method.

(Means for Solving the Problems) A malfunction recovery system for a subscriber line test lead-in switch according to the present invention includes a switch circuit and a power supply circuit.

This system includes a subscriber line test machine, a subscriber line test drop-in switch, and a subscriber line test drop-in switch malfunction detection and recovery circuit.

The switch circuit is connected to a subscriber terminal via a two-wire subscriber line and is used to switch line voltage polarity.

The power supply circuit is connected to the ground and the battery via a fixed resistor to the switch circuit, and is for monitoring the loop state of the subscriber line.

A subscriber line tester is used to test the functionality of subscriber circuits.

The subscriber line test lead-in switch is for controlling the connection state between the subscriber line and the subscriber line testing machine.

The subscriber line test drop-in switch malfunction detection recovery circuit compares the voltage of the subscriber line test drop-in line with a predetermined voltage, and outputs the comparison result, a power supply signal to the subscriber line, and drives the subscriber line test drop-in switch. Detects and maintains malfunction conditions of the subscriber line test drop-in switch using signals, controls power supply/stop to the power supply circuit and switch circuit, and displays all malfunction detection indications of the subscriber line test drop-in switch to the upper control device. It is something.

(Example) Next, one embodiment of the present invention will be explained with reference to the drawings.

FIG. 1 #-j:1 is a block diagram showing an embodiment of a malfunction recovery method for a subscriber line test lead-in switch according to the present invention.

In the first I/, l is a subscriber terminal, 2 and 3 are subscriber lines, 4 is a switch circuit, 5 is a power supply circuit, 6 is a subscriber line test lead-in switch, 7 is a subscriber line tester, and 8 is a subscriber line. User line test lead-in switch malfunction detection recovery circuit, 9.1
0 is each subscriber line 2.3t - drop-in line for testing. In the subscriber line test lead-in switch malfunction detection recovery circuit 8, 81 and 82 are comparators, 83 are reference voltage sources, 84 and 85 are AND gates, and 86
is an OR gate, and 87 is a latch circuit.

The switch circuit 4 has one end connected to the subscriber terminal 1 via a two-wire power line 2.3, and the other end connected to the power supply circuit 5. The switch circuit switches the polarity of the voltage applied to the subscriber line 2.3, and the power supply circuit 5 is connected to the earth and a battery via a fixed resistor, and supplies communication current to the subscriber terminal l. .

The subscriber line test lead-in switch 6 is a switch that controls the connection state between the subscriber line 2.3 and the subscriber line testing machine 7, and the subscriber line testing machine 7 controls the connection between the switch circuit 4 and the power supply circuit 5. Perform a functional test.

The subscriber line test drop-in switch malfunction detection recovery circuit 8 includes a drop-in line 9. for testing the subscriber lines 2 and 3.
10 and a predetermined voltage (Vref) obtained by a reference voltage source 83 are compared by comparators 81 and 82. Power supply signal (NOR, REV), subscriber line test lead-in switch drive signal (LTD), comparator 81°82
A malfunction condition of the subscriber line test lead-in switch 6 is detected by the t-OR+ gate 86 based on the output signal of the t-OR+ gate 86, and is further held using the latch circuit 87. At this time, the latch circuit 87 is connected to the switch circuit 4. and MSL to power supply circuit 5
Outputs T signal. The M8LT signal controls the stoppage of power supply and also displays all malfunction detection of the subscriber line test lead-in switch 6 to the higher-level control device.

In the call monitoring state where subscriber terminal 1 is on-hook,
The subscriber circuit supplies subscriber line 2 from -vBBpol)1-battery and supplies subscriber line 3 from the ground. In the case of a normal power supply state, the NOR signal becomes active, and the subscriber line 2 is supplied with -VBB volts from the battery, and the input line 3 is supplied with earth air. Furthermore, the subscriber terminal 1 is supplied with communication current. On the other hand.

In the case of the reverse power supply state, the REV signal is active, and a communication current having a polarity opposite to that of the normal power supply is supplied.

If power is normally supplied during a call, the potential of the subscriber line 2 is maintained within the range of 1 dVnn volts to -VBB volts. Here, if the subscriber line test drop-in switch 6 is erroneously turned on due to a sudden voltage change occurring on the subscriber terminal side, the potential of the subscriber line test drop-in line 9 will be different from the potential of the subscriber line 2. be equal.

Therefore, the subscriber line test drop-in switch malfunction detection recovery circuit 8 changes the potential of the subscriber line test drop-in line 9 to the reference voltage source 83.
By comparing the voltage with a predetermined voltage, it is possible to detect and display the condition as to whether or not the subscriber line test lead-in switch 6 has malfunctioned. Further, by monitoring the subscriber line test drop-in switch malfunction detection display signal (MELT) by the higher-level control device, malfunction of the subscriber line test drop-in switch 6 can be detected. Therefore, the subscriber line test lead-in switch malfunction detection recovery circuit 8 is initialized by the RMSLT signal, and furthermore, the restart of power supply to the switch circuit 4 and the power supply circuit 5 is controlled.

(Effects of the Invention) As explained above, the present invention compares the potential of the subscriber line test drop-in wire with a predetermined voltage in the subscriber line test drop-in switch malfunction detection and recovery circuit to determine the malfunction condition of the subscriber line test drop-in switch. By detecting this and fully controlling the power supply to the switch circuit and power supply circuit, it is possible to display a malfunction of the subscriber line test drop-in switch to the higher-level control device. It is possible to suppress wasted communication current consumption in the power supply circuit formed by multiple low resistance loops, and in addition, the upper level control device uses the subscriber line test lead-in switch malfunction detection display signal to check the subscriber line This has the effect that abnormal conditions can be quickly detected.

Furthermore, since the call status of the subscriber circuit can be reset, there is an effect that the service to the subscriber can be completely improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a malfunction recovery system for a subscriber line test lead-in switch according to the present invention. 1...Subscriber terminal 2.3...Subscriber line 4...
Switch circuit 5...Power supply circuit 6...Subscriber line test lead-in switch 7...Subscriber line test machine 8...Subscriber line test lead-in switch malfunction detection recovery circuit 9, 1O...Subscriber line Test lead-in wire 81.82...Comparator 83...Reference voltage source 84
．． 85...AND gate 86...OR gate 87...Latch circuit patent applicant NEC Corporation

Claims (1)

[Claims] a switch circuit connected to the subscriber terminal by a two-wire subscriber line for switching the line voltage polarity; and a switch circuit connected to the earth and the battery via a fixed resistor to the switch circuit and connected to the subscriber terminal through a fixed resistor. a power supply circuit for monitoring a loop state of a line; a subscriber line testing machine for performing a functional test of a subscriber circuit including the subscriber line; and between the subscriber line and the subscriber line testing machine. A subscriber line test drop-in switch for controlling the connection state of the subscriber line, compares the voltage of the test drop-in line of the subscriber line with a predetermined voltage, outputs a comparison result, a power supply signal to the subscriber line, and A malfunction condition of the subscriber line test drop-in switch is detected and held using the subscriber line test drop-in switch drive signal, and power supply/stop control is performed to the power supply circuit and the switch circuit, and the subscriber line test is performed to the upper control device. A method for recovering a malfunction of a subscriber line test drop-in switch, comprising: a subscriber line test drop-in switch malfunction detection recovery circuit for displaying detection of malfunction of the subscriber line test drop-in switch.