JPS6244454B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data terminal device connected to a subscriber telephone line via a network control device.

In recent years, systems in which a central device collects data from terminal devices in remote locations using subscriber telephone lines (hereinafter referred to as telephone lines), such as automatic meter reading systems that automatically read the usage of water, gas, electricity, etc. is being considered.

FIG. 1 shows an example of the configuration of the data collection system described above, and the configuration of this system will be briefly explained below.

In FIG. 1, 1 is an exchange, 2 is a subscriber telephone line (hereinafter referred to as a telephone line), 3 is a subscriber telephone connected to telephone line 2, 4 is a network control device connected to telephone line 2, and 5 is a network control device. 4, a data terminal device (hereinafter referred to as a terminal device) whose connection is controlled by 6,
Reference numeral 7 denotes an encoder that reads meter reading values for water, gas, etc., for example.

In such a configuration, for example, in order to collect meter reading data from the encoder 6, the exchange 1 first captures the telephone line 2, and then a specific terminal calling signal (this signal rings the bell of the telephone 3) is sent from a center device (not shown). ) is sent to telephone line 2, and the polarity of telephone line 2 is reversed. Network control device 4 detects this terminal call signal and connects terminal device 5 to telephone line 2.

When the terminal device 5 is connected to the telephone line 2, data communication becomes possible between the center device and the terminal device 5. A selection code is sent, and the terminal device 5 detects this selection code, selects and activates the specified encoder 6, reads the meter reading data, converts it into an AC signal, and sends it to the center device, thereby collecting data. It can be done.

By the way, this type of data collection system has not yet been put into practical use, but it may be possible in the future.
If this data collection system is put into practical use on a large scale and in a wide range of subscriber homes, the number of installed terminal devices and encoders will increase significantly, and it will become possible to apply it to various data collection systems. Those with various functions may be used. Therefore, in such a case, it is desirable that the terminal device be able to connect to different encoders as well. That is, it is desirable to be able to connect a plurality of types of encoders with different data lengths in transmission formats, different command information, or different error control methods, for example.

However, in order to realize a terminal device that can be connected to multiple types, the data received from the encoder must be decoded within the terminal device, error control, reception end monitoring, etc. When performing this processing, there are problems such as the hardware configuration of the terminal device becoming complicated and miniaturization becoming difficult.

The present invention has been made in view of the above-mentioned points, and its object is to provide a data terminal device with a simple configuration and a function capable of connecting to different encoders.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows an embodiment of the present invention, and the same parts as in FIG. 1 are given the same reference numerals.

In FIG. 2, the terminal device 5 includes a coupling circuit 51, a demodulator 52 that demodulates a signal subjected to frequency shift keying (hereinafter referred to as FS modulation), a decoder 53 that decodes the demodulated output of the demodulator 52, a latch 54, and a gate 5.
5. Timer 56, OR circuit 57, modulator 5 that performs FS modulation on the transmission data from encoder 6 or 7.
It consists of 5 etc.

Hereinafter, the operating state of the terminal device 5 in the configuration shown in FIG. 2 will be explained with reference to FIGS. 3 a to 3 e.

A to E in the same figure show the waveforms a to e of each part in FIG. 2, and the reference numerals correspond to each other. In FIG. 3, section _T1 indicates an operating state in which a selection code sent from a center device (not shown) is received, and section _T2 indicates an operating state in which meter reading data from an encoder is transmitted to the center device.

The operation will be described below by taking as an example the case where meter reading data is collected from the encoder 6.

First, the operation in section _T1 will be explained. After the exchange 1 captures the telephone line 2 as described above, it sends a specific terminal calling signal sent from the center equipment to the telephone line, and when the polarity of the telephone line 2 is reversed, the network control equipment 4 receives this terminal calling signal. The terminal device 5 is detected and connected to the telephone line 2.

When the terminal device 5 is connected to the telephone line 2, the center device transmits an FS-modulated selection code.
In the terminal device 5, this selection code a (FIG. 3a) is guided to a demodulator 52 via a coupling circuit 51 and demodulated. The decoder 53 decodes the output b (FIG. 3b) demodulated by the demodulator 52 and produces a decoded output c (FIG. 3c) corresponding to the selected code a. The decoded output c is held in latch 54.

Next, the operation in section _T2 will be explained. When the demodulated output b is decoded by the decoder 53, the timer 56 starts operating immediately or after a certain period of time, and the timer output d (FIG. 3 d) opens the gate 55 and selects one of the plurality of encoders. A DC voltage is applied to the encoder 6 to activate the encoder 6 and to put the modulator 58 into operation, thereby starting to send the carrier to the center device via the coupling circuit 51. Note that in this case, the demodulator 52 is in an inactive state.

The encoder 6 activated by the terminal device 5 changes the applied DC voltage by controlling on/off a switch circuit (not shown) in accordance with the meter reading data. The OR circuit 57 of the terminal device 5 guides meter reading data corresponding to this change to the modulator 55, and performs FS modulation. The FS modulated signal is sent to the center device via the coupling circuit 51, and end needle data is collected.

On the other hand, the timer 56 becomes inactive after a predetermined period of time has elapsed, and the timer output d causes the modulator 58 to stop transmitting the carrier, and the gate 5
5 is closed, and application of DC voltage to the encoder 6 is stopped. When the application of the DC voltage is stopped, the encoder 6 changes depending on the timing.
various operations are restored, and the terminal device 5 waits in a state where it can be restarted.

That is, the terminal device 5 uses the timer 5 regardless of the type of transmission format transmitted from the encoder 6.
The transmission data from the encoder 6 is received only during a predetermined time period when the encoder 6 is in operation.

Note that when the timer 56 becomes inactive, the demodulator 52 becomes active and can subsequently receive other selection codes sent from the center device.

As explained above, the present invention provides a data collection system using subscriber telephone lines, in which a data terminal device having a function of selectively activating an encoder starts operation immediately or after a certain period of time when a data terminal device having a function of selectively activating an encoder decodes a selection code sent from a center device. A timer is set up so that it becomes inactive after a predetermined period of time has elapsed.
Since the configuration directly modulates and transmits the meter reading data received from the activated encoder, it has the advantage that the type of transmission format transmitted from the encoder is not limited, and no special data processing is required inside the data terminal device. This structure simplifies the configuration, and there is no possibility of code errors occurring in the data processing section.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of the configuration of a conventional data collection system, Fig. 2 is a block diagram showing an embodiment of the present invention, and Figs. 3 a to e explain the operation of the embodiment of Fig. 2. FIG. DESCRIPTION OF SYMBOLS 1... Exchange, 2... Subscriber telephone line, 3... Subscriber telephone, 4... Network control device, 5... Data terminal device, 6, 7... Encoder, 51... Coupling circuit, 52... Demodulator , 53...decoder, 54...
...Latch, 55...Gate, 56...Timer, 5
7...OR circuit, 58...modulator.

Claims (1)

[Claims] 1. Connected to the subscriber telephone line via a network control device that detects and controls connection of a specific terminal call signal sent from the center device to the subscriber telephone line, and activates multiple types of encoders to extract information from these encoders. The data terminal device that receives the transmitted data includes a demodulator that demodulates the frequency-shift keyed selection code sent from the center device side, and a demodulator that demodulates the selection code that is transmitted from the center device side, and immediately or After a predetermined period of time, it enters an operating state and starts timing, and when a predetermined time elapses, it enters an inactive state, and during the operating state, the demodulator is in an inactive state, and during the inactive state, the demodulator a timer that activates the encoder corresponding to the selection code while the timer is in the operational state; and a gate that is activated while transmitting the carrier while the timer is in the operational state. 1. A data terminal device comprising: a modulator that receives data from an encoder, performs frequency shift modulation on the received data, and sends the received data to a center device.