JPH05316245A - Network controller for terminal - Google Patents

Abstract

PURPOSE:To obtain a network controller by which a terminal call operation can be exactly attained regardless of the kind of a switchboard even during a no ringing communication without having a detecting circuit which detects a call sound or a busy tone inside. CONSTITUTION:At the time of detecting the usage of a telephone set by a detected voltage from a line voltage detecting circuit 3, a terminal call NCU circuit 2 operates an off-hook operation once. Afterwards, a timer circuit 4 measures the off-hook identification time of the switchboard, and a line restoration time, and a CPU 1 operates an on hook operation and the off-hook operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terminal network controller (hereinafter referred to as "T-NCU"), and more particularly to a terminal call communication operation.

[0002]

2. Description of the Related Art In recent years, when performing automatic meter reading for metering the amount of water, gas, electricity, etc., each piece of information scattered over a wide area is sequentially activated from a master station to a slave station. As a simple way to collect, general subscriber telephone lines (hereinafter,
There is a no-ringing system that collects information without ringing the telephone bell using a telephone line). A configuration diagram of a typical no ringing communication system is shown in FIG. In FIG. 5, 1 is an electronic computer (CPU),
2 is a center network control unit (C-NCU), 3 is a transmitting station connected to the center side, 4 is a receiving station connected to the terminal side,
5 is a special trunk added to the exchange of the called station 3 in the actual ringing system, that is, a no ringing trunk (NRT), 6 is a T-NCU, 7 is an information source such as a meter, and 8 is a subscriber telephone. Also, 11 is a connection line,
12 is a telephone line on the center side, 13 is a relay line between offices, 14 and 1
5 and 16 are interface lines between the exchange 4 and the NRT 5,
17 is a subscriber telephone line, 18 is a telephone 8 and TNR-NCU6
Reference numeral 19 is a connection cable with and a meter cable or the like.

This system starts with NRT5 from the center.
Is connected, and then the subscriber telephone line 17 is connected from the NRT 5 while holding the NRT 5 so that the center and the subscriber telephone line 17 are connected. When the subscriber telephone line 17 is connected from the NRT 5, by transmitting a special signal without transmitting a bell signal, the T-NCU 6 is activated without ringing the bell of the telephone 8 to enable data communication. The T-NCU 6 operates by using the station power supplied via the subscriber telephone line 17, has a no-ringing incoming network control function, a data modulation / demodulation function, and a meter selection start function, and is connected to the meter 7 etc. via a cable 19. It Also, a multiple ringing signal type no ringing system capable of connecting a plurality of T-NCUs to a telephone line is also used.

[0004]

In the case of the no ringing system of the multiple call signaling system, a plurality of T's are connected to the telephone line.
-Because the NCU is connected, when one terminal is calling communication while the other is no ringing communication, off-hook detection may not be normally performed depending on the type of exchange.

FIG. 3 and FIG. 4 show the connection operation at the time of calling a terminal during the no-ringing communication of each exchange, but there is a difference in the off-hook detection operation between the electronic exchange and the crossbar exchange. That is, in the electronic exchange of FIG. 3, a dial tone (hereinafter referred to as DT) is sent from the exchange to the telephone off-hook to receive dialing. However, in the crossbar exchange of FIG. 4, a busy tone (hereinafter referred to as BT) is transmitted from the exchange to the telephone off-hook, and dialing cannot be accepted. For this reason, DT, BT in T-NCU
Should be detected.

For example, when a crossbar switch is used,
When BT is detected, the calling operation may be stopped and the terminal may be called again. However, since the BT detection circuit must be provided in the device, it becomes a factor of increasing the size and cost of the device. If we don't have a BT detector,
Normally, the dial signal is unconditionally transmitted 3 seconds or more after the off-hook, so that the terminal cannot be surely called when connected to the crossbar exchange.

It is an object of the present invention to provide a terminal network control device which can reliably make a terminal call regardless of the exchange during no ringing communication without having a detection circuit inside.

[0008]

In order to achieve the above object, the present invention is directed to a network control for a terminal which is connected to a subscriber telephone line and transmits metering data on the terminal side to a center side via a switch when a call is made from the terminal. In the device, when the line recovery time of the subscriber telephone line and the time to identify the off-hook of the exchange are measured, the first off-hook means for off-hooking when the terminal makes a call, and the off-hook identification time of the exchange are measured by the timer means. With the on-hook means for on-hook and the second off-hook means for off-hook again when the line recovery time is measured by the timer means, the terminal call operation can be performed regardless of the type of the exchange.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a block diagram of a terminal network control circuit of the present invention, FIG.
FIG. 6 is a timing diagram showing an embodiment of a terminal call operation of the present invention.

In FIG. 1, reference numeral 1 denotes a CPU, which performs a series of processing of the terminal calling operation shown in FIG. 2 is T-NCU
The circuit is off-hook when the voltage of the telephone line detected by the line voltage detection circuit 3 is normal.

Reference numeral 4 denotes a timer circuit, which measures the time until an exchange (not shown) identifies off-hook, the time until the telephone line is restored (T1, T2, T3 shown in FIG. 2). Reference numeral 5 is a meter interface circuit (hereinafter referred to as a meter I / F circuit) for performing data communication between the T-NCU and a meter (not shown), and 6 is a modem for transmitting and receiving data communication. Next, regarding the operation, FIG.
Will be described.

Since the line voltage of the telephone line changes depending on whether or not a telephone (not shown) is used, the line voltage detection circuit 3
Detects that the telephone is in use from the line voltage, T-NC
The U circuit 2 goes off-hook once. After that, the time T1 at which the exchange (not shown) identifies the off-hook by the timer circuit 4
When measuring (for example, 1 second), the CPU 1 goes on hook. Further, when the timer circuit 4 measures the line recovery time T2 (for example, 2.2 seconds), the CPU 1 goes off-hook again. This is because the DT is always sent after the line restoration time in both the electronic exchange and the crossbar exchange. When the prepause time T3 (for example, 3 seconds) elapses from this state, dialing becomes possible.
With this configuration, even if the terminal calling operation is performed during the no ringing communication, the terminal calling can be reliably performed regardless of the type of the exchange.

[0013]

As described above, according to the present invention, in the terminal network control device which is connected to the subscriber telephone line and transmits the terminal side measurement data to the center side via the exchange when the terminal is called, the subscriber telephone line Timer means for measuring the line recovery time and the time for identifying the off-hook of the exchange; first off-hook means for off-hook when the terminal makes a call; on-hook means for on-hook when the off-hook identification time of the exchange is measured by the timer means; Since the second off-hook means for off-hooking again when the line recovery time is measured by the means, it is possible to reliably call the terminal regardless of the type of the exchange during the no-ringing communication even without the DT and BT detection circuit. It is possible to obtain a terminal network control device capable of performing operations.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a terminal network control device of the present invention.

FIG. 2 is a timing diagram showing an example of a terminal call operation of FIG.

FIG. 3 is a timing diagram of a terminal calling operation when a conventional electronic exchange is used.

FIG. 4 is a timing chart of a terminal calling operation when a conventional crossbar switch is used.

FIG. 5 is a block diagram of a typical no ringing communication system.

[Explanation of symbols]

1 ... CPU, 2 ... NCU circuit for calling terminal, 3 ... Line voltage detection circuit 4 ... Timer circuit

Claims (1)

[Claims] 1. A network control device for a terminal, which is connected to a subscriber telephone line and transmits the weighing data of the terminal side to a center side through an exchange when a call is made from the terminal, in a line restoration time of the subscriber telephone line and off-hook of the exchange. And a first off-hook means for off-hooking when the terminal makes a call, an on-hook means for on-hooking when the off-hook identification time of the exchange is measured by the timer means, and a line restoration by the timer means. A network control device for a terminal, comprising second off-hook means for making the hook go off-hook again when the time is measured.