JPS62164326A - Simplified signal transmission method - Google Patents

Abstract

PURPOSE:To execute the stable data transmission by modulating a carrier impressed from a master station to a cable line for transmission from a master station to a slave station and changing the impedance of the slave station to a non-modulating carrier impressed from the master station to the cable line for transmitting the data from the slave station to the master station. CONSTITUTION:By impressing a carrier modulated by the data to be transmitted from a master station through an injecting transformer 17 to an earth line 12, the carrier is transmitted to cable lines 8 and 10, a modulated carrier to induce between the cable line and the ground in the slave station is guided and by a receiving circuit 24, the data from the signal are demodulated and received. When the data are transmitted from the slave station to the master station, the non-modulating carrier different from the frequency of the modulated wave is impressed from the master station to the cable line, and at the slave station, a switch 27 is intermittently connected to the master station in accordance with the data to be transmitted. In the master station, after a feedback signal component is extracted by an electric galvanometer 13, the data are demodulated by a receiving circuit 14.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field to which the invention pertains) The present invention relates to a transmission method for realizing a simple local network using a low-voltage electric line such as a power line or a power line.

(Prior art) A method has been proposed that uses low-voltage electrical conductors such as electric light lines to transmit data in factories or small offices. It is extremely economical because it can effectively utilize the existing electrical circuits that have been extended up to

However, in the conventional data transmission system of this kind, for example, as shown in FIG. . . . and applying or receiving a data carrier signal to the electric lines 2 and 3, which caused various problems as described below.

In other words, the impedance characteristics of power transmission lines, such as electric power lines, are complex and depend on the distributed inductance, distributed capacitance, bypass capacitance, etc. between the lines, so the data signal level at the receiving point is is not constant and the attenuation is extremely large.

In addition, because the noise level induced on the road is high, communication S/
In addition to causing deterioration of N, the condition of the connected load equipment,
That is, data transmission characteristics vary greatly due to impedance changes, making it impossible to expect stable data transmission.

(Objective of the Invention) The present invention has been made in view of the circumstances explained above, and it provides a method of using an electric line that is stable and has low loss even when the transmission characteristics are extremely unstable due to nine various factors. The purpose is to provide a data transmission method.

(Summary of the Invention) In order to achieve this object, the present invention differs from the conventional method of applying transmission signals to the electric line by using the low-voltage electric line and the ground as a reciprocating transmission line. Furthermore, when a master station that applies a signal to the electric line and a slave station connected between the extension of the electric line and the ground transmit data using the electric line, the master station transmits data from the master station to the slave station. The carrier wave applied from the master station to the electric line is modulated with the data to be transmitted, and the slave station receives and demodulates this. Conversely, when transmitting data from the slave station to the master station, the carrier wave applied from the master station to the electric line is modulated by the data to be transmitted. The impedance of the slave station relative to the modulated carrier wave is changed in accordance with the data to be transmitted, and the master station detects the level or phase of the unmodulated carrier wave that returns via a grounding line of a power receiving transformer, etc. The configuration is configured to receive all data from the slave station.

With this configuration, the impedance between the electric line and the ground is generally very high and relatively stable, so the transmission signal level between all points on the line and the ground is constant, and the signal level is constant. The transmission characteristics are stable and the transmission loss is low, making it an extremely excellent transmission line.

The cause of such signal attenuation is mainly due to the grounding resistance of the grounding wire in Type 81!2 construction and the capacitance between the low-voltage power line and the ground, and it essentially does not affect the connection status of the load equipment on the low-voltage power line. Not done. For this reason, it has favorable conditions as a signal transmission path.

In addition, when transmitting data from a slave station to a master station, the impedance if for the carrier signal flowing through the cable of the slave station is simply
Since the configuration of a large number of slave stations installed in -ff is simple and economical, it is only necessary to make the slave stations digitized.

(Example) The present invention will be described in detail below based on an illustrated example.

Figure @1 is a block diagram showing one embodiment of the present invention.

In the figure, reference numeral 5 denotes a power receiving transformer installed in a power receiving room or the like, through which high voltage electricity (e.g. 6000 V) of the secondary coil 6 is transferred to electric lines 8 and 9 connected to the secondary coil 7.
．． The electric power is converted into low-voltage three-phase AC power (e.g. 200 V) and sent to the required parts via the extended electric line 8 to 10 gold, and this example shows the case where the present invention is applied to such an electric line. .

First, as a master station 11, a grounding wire 1 connected to one output line of the low-voltage secondary coil 7 of the normal power receiving transformer 5, for example, the center line 9.
a signal detection transformer 13 (for example, a zero-phase current transformer) coupled to the signal detection transformer 14 . A control device (CPU) 15 with necessary interfaces to control data transmission fees and the CPU 15
A transmitting circuit 16 for outputting an unmodulated carrier wave by superimposing the data output from the total carrier wave or by a command from the CP[J, and a signal output from the transmitting circuit for applying it to the electric lines 8 to 9 via the total ground line 12. The main station 11 is composed of an injection transformer 17 coupled to the ground line 12 as a main element.

Further, the slave station is constructed as shown in block 18 in the figure, and the electric circuit and the earth ground point are connected as input/output terminals.

That is, the slave station 18 has two terminals: a signal line terminal 20 connected to one of the electric lines, for example, the center line 9, via a signal line 19, and a ground terminal 220 connected to the earth ground point 21; A signal is led from the terminal 20 to a receiving circuit 24 via a DC blocking converter 23, and the data from the master station demodulated by this receiving circuit is input to a slave station control device 25 equipped with a required interface.

Further, for data transmission from the slave station to the master station, a filter 26 whose passband is the frequency of the af-toned carrier signal sent from the master station 11 is installed between the signal line terminal 20 and the ground terminal 22.
A series circuit network with a switch 27 having an important control terminal is inserted and connected.

However, a damper resistor is inserted so that the pass band inopedance of this filter does not become extremely small compared to the insulation resistance of the electric circuit.

Furthermore, an adult switch on/off signal based on the data to be transmitted from the slave station control device 25 is input to the important control terminal of the switch 27.

The signal line 19g of the subsidiary station may be connected to any of the electric lines 8 to 10, but it is preferable to select the electric line 9 which is grounded at the power receiving tray/block as in the above-mentioned embodiment. Dew.

The reason for this is that since the commercial power supply voltage is applied to the other electrical circuits 8 and 10, an expensive filter is required to remove the commercial power frequency in the receiving circuit 24 of the slave station, and a The inserted series circuit networks 26 and 27 also require all measures to block the high voltage (for example, OOV, 200V) commercial power supply, which would increase the economic burden, which would be disadvantageous.

Further, a capacitor 23 inserted before the receiving circuit 24 is provided for blocking the DC voltage of a megger used to measure the insulation resistance of an electric circuit.

Furthermore, it is desirable to operate the I/V Danos for the electric circuit of this slave station at as high an impedance as possible. This is because there is a risk that it may be mistaken for a problem such as poor insulation.

The operation of the above configuration will be explained.

First, the data transmission operation from the master station to the slave stations is performed by applying a carrier wave modified by the data to be transmitted from the master station to the grounding line 12 via the injection transformer 17, as has been done in the past. 8 to 10,
In the slave station, the modulated carrier wave induced between the electric line and the ground is derived, and after the reception circuit 24 demodulates and receives all data from this signal, the control device 25 performs predetermined signal processing. 'On the other hand, when transmitting data from the slave station to the master station, the master station applies an unmodulated carrier wave different from the frequency of the modulated wave to the electric line, and the slave station applies the switch 27 to the master station. connection/disconnection according to the data to be transmitted.

In this way, the unmodulated carrier wave transmitted from the master station and applied to the electric line flows to the ground via the filter 26 inserted in series with the switch 27 of the slave station when the switch is connected.

This will return to the master station grounding line 12 via the earth.

In the master station, as mentioned above, all the feedback signal components of the unmodulated carrier wave sent from the master station are extracted by the galvanometer 13 connected to the ground wire 12, and then the level change or From the phase change, it is possible to detect whether the switch 27 of the slave station is connected or disconnected, and to read the data transmitted from the slave station.

Similarly, the filter 26 of the slave station passes only the unmodulated carrier wave sent from the master station.

Other carriers modulated by the data to be transmitted from the master station at the same time @? The slave station can receive and demodulate all of the signals. Furthermore, both the modulated carrier wave and the unmodulated carrier wave sent from the master station to the slave station are not limited to one each, but can be arbitrary, and the configuration of the slave station corresponding to this is also possible. Various things are possible.

That is, one of them is the transmission circuit 16 as shown in FIG.
When considering a master station that is equipped with a large number of receiver circuits and a total number of receiver circuits 14, and applies an arbitrary number of modulated carrier waves and unmodulated carrier waves with different frequencies from each transmitter circuit to the electric line, the corresponding slave station is The same number of receiving circuits, filters, and switches as the master station has as shown in FIG. However, it is conceivable to make the passing frequency of the filter different for each slave station depending on the unmodulated carrier frequency sent out from the master station. With this method, it is possible to simultaneously send and receive data to and from a large number of slave stations using the same electrical path.

Although the basic embodiments of the present invention have been described above, the present invention is not limited thereto, and various other forms of use can be considered.

For example, data transmission can be performed from a slave station to another slave station. One method in this case is to assign an address to each slave station, send the data to be transmitted to the master station, convert it into a signal format that the slave stations can receive, and then send it to the target slave station. Just resend it.

Similarly, as is clear from the above explanation, this retransmission from the master station can be performed at the same time as data reception from the slave station, and data transmission from a slave station to other slave stations can be performed simultaneously over multiple lines. It will be easy to understand what is possible if we consider the constituent sounds as explained in the second u (al (bl).

Furthermore, it is also possible to apply various transmission forms that have conventionally been generally used in local area networks (LANs).9According to the present invention, a simple LAN
can be configured.

For example, each slave station decodes the address added to the data signal sent from the master station and only takes in the data and processes or transmits the signal when it belongs to its own station, or In order to prevent communication troubles caused by transmission, so-called collisions, it is not a problem to adopt a token passing method or the like in which tokens are circulated for each channel.

In addition, the data modulation method in the slave station is the width modulation (AM), which is simply turned on and off using a switch circuit, as in the example above.
) method, it is also possible to change the phase of the carrier wave according to the data; in this case, for example, a variable phase shifter may be inserted in place of the switch, and this may be changed according to the data. Alternatively, phase shift keying modulation (PSK) is performed by switching a circuit with binary actance based on data.
It will be obvious that various modulation methods may be employed, such as performing modulation).

Further, the electrical circuit to which the present invention is applied need not be limited to a power transmission line, and may be any circuit as long as it satisfies the functions described above in principle, and no explanation is necessary.

(Effects of the Invention) According to the signal transmission method of the present invention, it is possible to construct an extremely economical star-shaped or, in some cases, ring-shaped local network, and it is possible to construct an extremely economical star-shaped or, in some cases, ring-shaped local network. etc., stable data transmission can be achieved. Furthermore, if a common address is provided in addition to the individual addresses of each station, it is possible to easily implement a circular communication in which data is transmitted to all terminals in factories, offices, etc. at once.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 (
at and (bl are block diagrams showing other embodiments of the present invention, and FIG. 3 is a block diagram showing a conventional method. 5... Power receiving transformer; 7...
...Secondary coil, 8,9.10...
...Electric circuit. 11・・・・・・・・・Master station, 12・・・・・・
・−・Grounding wire. 13・・・・・・・・・ Galvanometer, 14.24・
...... Receiving circuit, 15.25...
······Control device. 16...... Transmission circuit, 17...
...Injection transformer, 18...
・Slave station, 19... Signal line,
20......Signal line terminal. 21... Grounding point, 22...
...Grounding terminal. 26...Filter, Q7...
−・・・Paswitch.

Claims (1)

[Scope of Claims] 1. A master station that applies a carrier wave for signal transmission to an electric line via a grounding line of a power receiving transformer, etc., and a slave station that is on an extension of the electric line and connected between the electric line and the ground. In this combination, when transmitting data from the master station to the slave station, the carrier wave is modulated by the data to be transmitted, and the slave station receives and demodulates the carrier wave. Further, in order to transmit data from the slave station to the master station, the master station applies an unmodulated carrier wave of a different frequency to the electric line in addition to the modulated carrier wave, and the slave station applies an unmodulated carrier wave of a different frequency to the unmodulated carrier wave. The impedance of the own station is changed depending on the data to be transmitted, and the master station detects changes in the level or phase of the unmodulated carrier wave that returns to the ground line etc. A simple signal transmission method characterized by receiving data. 2. A patent characterized in that the data transmitted by the master station includes address information of the slave station, and the slave station transmits its own data only when the received data includes address information of the slave station. A simple signal transmission method according to claim 1. 3. The transmitted data from the master station includes common address information, and when multiple slave stations include common address information in the received data, they judge that the received data is information addressed to all the slave stations and process it. A simple signal transmission method according to claim 1, characterized in that: