JPS62155696A - Remote supervisory and controlling equipment - Google Patents

Abstract

PURPOSE:To reduce the restriction for the distance of a transmission path and the number of branches of the transmission path by presetting the frequency of a signal transmitting from a master station to a slave station and the frequency of a signal transmitting from the slave station to the master station to different values and forming a transmission request signal based on a received signal by the master station when the master station receives the signal from the salve station. CONSTITUTION:In the case of the constitution of a pair of transmission paths as shown in the drawing, a modulating frequency is allocated to f1 (master station) and f2 (slave station) so as to discriminate whether it is the signal from the master station 10 to the slave stations 11, 12 or the signal from the salve stations 11, 21 to the master station 10. When the master station 10 detects the modulating wave f2 from the salve stations 11, 21 by a demodulator 102, it transmits the modulating wave f1 (modulating wave on which a specific signal is not mounted) to the respective slave stations 11, 21 through a modulator 101 of its own station. As a means therefore,the master station has a constitution for inputting the OR signal RSO' of the transmission request signal RSO from a transmitter T in its own station and the carrier detection signal CDO of the modulating wave f2 signal from the slave station which is detected through the demodulator 102 as the transmission request signal of the modulator 101.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a remote monitoring and control device, in particular, to a remote monitoring and control device that controls devices at multiple locations (hereinafter referred to as slave stations) from a control device at one location (hereinafter referred to as a master station). This invention relates to a remote monitoring and control device.

[Technical background of the invention]

In a remote monitoring control system, a method for controlling a plurality of slave stations from one master station is generally called a 1:N configuration control method, and FIG. 4 shows the configuration sequence of this method. This configuration is often employed when remotely monitoring and controlling a pole switch or an underground switch installed on a power distribution line.

Further, this configuration is characterized in that one or two pairs of transmission lines are branched in the middle in a multi-drop manner, and each slave station is connected to this branched transmission line. That is, the transmission path L0 from the master station 10 is a plurality of transmission paths.

...Lk, and each branched transmission line L1. L
,.

Each slave station 11...11.21...2m is connected to Lk, and E...kn is connected to ~.

In this case, the signal transmitted from the master station 10 must be received at a normal reception level by all the slave stations via each branched transmission path, and on the other hand, the signal from each slave station must also be received at a normal reception level. It must be received by the master station at the receiving level.

The transmission method employed in this type of configuration is generally a polling method. In the polling method, the master station gives "transmission permission" to the slave stations in turn, and the only slave station that receives permission transmits data.On the other hand, when the master station wants to transmit data to the slave stations, the master station gives "transmission permission" to the slave stations in turn. This is a method in which the transmission data is sent to the slave station after the transmission from the slave station is completed. Therefore, interference on the transmission path can be prevented. However, even if the slave station generates information that it wants to notify to the master station, there is a drawback that the information cannot be transmitted to the master station until the slave station receives a call from the master station. In this case, if the number of slave stations connected to one transmission path is large, the paging cycle becomes slow in proportion to the number of slave stations, and the response time for information also becomes slow.

One way to solve this problem is to use contention (Cont.
) or C3MA/CD (Carri
er SenseMultl-Acesss/Co1
There is a method called 1 talon detector) method.

In this method, each station that wishes to transmit information, including the master station, obtains the right to transmit on the condition that there is no other station's signal (carrier) on the transmission path, and then begins transmission. . In this case, if multiple stations start transmitting at the same time, poor reception will occur on the receiving station side. Therefore, since the receiving station does not return a "receivable signal" indicating that the data has been correctly received to the transmitting station, each station that has already transmitted transmits again. At this time, the transmission times of the plurality of stations are staggered. That is, the station that starts transmission earliest obtains the right to transmit and starts transmitting, and after that transmission is completed, the remaining stations sequentially obtain the right to transmit and transmit using the same procedure.

In short, in the C8MA/CD system, each station needs to be able to detect whether or not a signal from a station other than its own station is being transmitted on the transmission path.

The conventional method for this detection will be explained with reference to FIG.

In addition, in order to simplify the explanation, FIG. 5 shows a case where there are two slave stations for the master station 10, and each of these slave stations is connected to a pair of transmission paths that are branched into two, , L, Andori,
The configuration is such that they are connected to each other.

Each station includes a transmitter/receiver 104, 114, 214, a modulator 101, 111, 211, a demodulator 102, 112, 21
2. Transformer 103゜113.213 connected to transmission line
Each station is equipped with automatic gain controllers AGC105 and 115°215 on the receiving side.

FIG. 6 shows a modified example of the station configuration, with a modulator 11, a demodulator 1
2. A transformer 13, a transmitter/receiver 14, and a carrier detector 16 are provided.

And between the transmitter/receiver and the modulator and demodulator, modulated input signals SD, SDO, SDI, Sn2 and transmission request signals R8, R8O, R8I, R82 are inputted on the transmitting side, and demodulated signals RD, R82 are inputted on the receiving side. RDO, RDI,
RD2 and carrier detection signals CD, CDO, CDI
, CD2 is delivered.

Next, a case where the slave station 11 starts transmission will be described.

The slave station 11 receives the carrier detection signal CDI from the demodulator 112.
The transmission request signal R8I of the modulator 111 is output under the condition that there is no transmission, that is, with the recognition that no other station other than the own station is transmitting. Next, the carrier of the own station is modulated by the modulated input signal SDI, and outputted to the transmission line L1 at a specified level via the transformer 113. At this time, the master station 10 other than the slave station 11 and the other slave stations 21 receive the signal attenuated according to the distance of the transmission path from the slave station 11 via the transformers 103 and 213, and send it to the AGC 105. , 215. Since the received signal is attenuated, it is amplified to a specified level by the AGC and input to the demodulator 102.212.

From the demodulators 102 and 212, carrier detection signals CDO,
CD2 is output and demodulated output SDO.

SO2 is output.

On the other hand, the transmitter/receiver 104 and 214 respectively perform reception processing on the condition that the carrier detection signal is present and the demodulated outputs SDO and SO2 are present.

Considering the master station 10, since the information received from the slave station 11 is directed to the own station, a recognition signal indicating that this information has been correctly received is sent to the modulator 101 and the transformer 1.
03 to all slave stations. Furthermore, the slave station 21 recognizes that another station is transmitting and does not perform any processing.

On the other hand, when the slave station 11 receives the recognition signal from the master station 10, it understands that the information from itself has been correctly transmitted to the master station, and ends the transmission process. In addition, if the slave station 11 cannot correctly receive the recognition signal from the master station 10, the slave station 11
1 performs the transmission process again. The above is an explanation of the basic operation.

[Problems with background technology]

In the case of the conventional device having the above configuration, a difference occurs in the reception level depending on the connection position of each station. That is, the reception level of a signal transmitted from a slave station connected to the end of a transmission path is significantly different between a slave station connected to the end of another transmission path and a slave station and a master station connected in the middle. As a countermeasure, each station has
This requires setting up a GO and automatically adjusting, which is technically difficult. In this case, if the reception level of the signal is too low, the difference from noise in the transmission path will be small, and as a result, the signal cannot be received correctly. In short, there is a limit to the transmission distance with conventional devices.

In addition, in FIG. 6, the AGC in each station is omitted, and in its place a carrier detector 16 that detects only the carrier is installed in the demodulator 1.
2 are connected in parallel.

In this case, whether or not another station is transmitting is determined based on the presence or absence of the carrier detection signal CD' by the carrier detector 16, but as described above, there is a limit to the transmission distance.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a remote monitoring and control device in which restrictions on the distance of a transmission line and the number of branches of a transmission line are reduced.

[Summary of the invention]

In the present invention, the frequency of the signal transmitted from the master station to the slave station,
The frequency of the signal transmitted from the slave station to the master station is changed and set in advance, and when the master station receives a signal from the slave station, the master station regenerates and amplifies this received signal. It transmits to all slave stations using the designated frequency, making them aware that a particular slave station is transmitting.

[Embodiments of the invention]

Examples will be described below with reference to the drawings. FIG. 1 is a block diagram of a simple embodiment of a remote monitoring and control device according to the present invention. In FIG. 1, the same parts as in FIG. 5 are designated by the same reference numerals, and the explanation thereof will be omitted.

The difference between this embodiment and the conventional configuration shown in FIG. 5 is that AGC is removed from each station 10, 11.21 including the master station;
In the case of the pair of transmission path configuration shown in FIG.
In order to be able to distinguish between the signals from the slave stations 11 and 21, the modulation frequency is assigned to the FTC master station), f, and C slave station). is detected, each slave station 11 .
It has a configuration that can send out a modulated wave f□ (modulated wave on which no specific signal is carried) to 21. As a means for this purpose, the master station uses the transmission request signal R8O from the transmitter/receiver 104 in its own station, the modulated wave f from the slave station detected via the demodulator 102, and the double signal carrier detection signal CDO. The configuration is such that the OR signal R8O' is input as a transmission request signal to the modulator 101. The other configurations are the same as in FIG. 5.

FIG. 2 is a time chart for explaining the operation, in which the left side of the dashed-dotted line shows the state when data is transmitted from the slave station to the master station, and the right side shows the state when data is transmitted from the master station to the slave station.

First, a case where transmission information is generated from the slave station 11 to the master station 10 will be described. The slave station 11 confirms that there is no carrier from another station on the transmission path using the carrier detection signal CD1 from the demodulator 112, and outputs the transmission request signal R8I at time t0. As a result, a modulated wave CRf appears on the transmission path [phase]. At time tl, the master station 10 converts the modulated wave CRf from the slave station 11 into the carrier detection signal CDO of the demodulator 102.
The slave station 11 then modulates the signal by the modulation input signal SDI, and immediately outputs the transmission request signal R8O' to the OR circuit 106. ■Transmit a signal to 10. In this case, the slave station 11 that is transmitting and the slave station 21 that is not in the transmitting state each receive the modulated wave CRf from the master station 10, and the slave station 11
outputs the carrier detection signal CDI (2), and the slave station 21 outputs the carrier detection signal CD2 (2). At this time, the slave station 11 that is currently transmitting continues to transmit, but the slave station 21 that is not in the transmitting state recognizes that another station is transmitting. When the slave station 11 finishes transmitting at time t, the carrier detection signal CDO of the master station 10 turns OFF, so the transmission request signal R8O' also turns OFF, and the modulated wave CR/□ is output from the master station 10. will also stop.

Next, the case where the master station 10 transmits to a predetermined slave station or all slave stations will be explained.

The master station 10 receives the carrier detection signal CDO from the demodulator 102.
It is confirmed that there is no carrier from another station on the transmission path, and at time t0, the transmitter/receiver 104 of the master station 1o outputs a transmission request signal R8O, and this is outputted as R8O' via the OR circuit 106. . As a result, the modulated wave CR8 from the master station 10 is outputted from the modulator 101 to the transmission path.

At time t, each slave station 11, 21 outputs the carrier calibration signals CDI, CD2 and recognizes that Q1's own station is not transmitting and that the other station is transmitting. Then time t.

At , each slave station 11, 21 receives a signal modulated by the modulated input signal SDO from the master station 10. and time t
When the transmission from the master station 10 ends at , there is no carrier at all on the transmission path.

As is clear from the above description, by simply adding a circuit to the master station 10, the AGC circuit can be omitted, and the carrier detection circuit can also be omitted. Further, the transmission level of each slave station is semi-fixedly adjusted in advance so that the reception level is the same. In this case, the transmission level of the master station is sent out at the maximum level, and each slave station can be semi-fixedly adjusted to the reception level according to the loss on the way, so maintenance is easy and noise can be reduced. This can prevent malfunctions due to

FIG. 2(b) is a detailed diagram of the modulated input signal, and the inside of the pulse signal is naturally f1 with respect to the center frequency f.
+Δf or fl−Δf.

FIG. 3 is a block diagram of another implementation of the master station.

In this implementation sequence, the demodulated output RDO received from the slave station is also ORed.
A circuit 107 performs regenerative amplification. Therefore, any station can correctly receive signals from other stations.

In the above embodiment, the master station and the slave station are connected through a pair of transmission paths, and different frequencies are assigned to the master station and the slave station, respectively. However, the present invention is not limited to this. By using a pair of transmission lines, it is possible to use the same frequency, and a coupling transformer is not required.

〔Effect of the invention〕

As explained above, according to the present invention, the transmission frequency is changed and assigned from the master station to the slave station or from the slave station to the master station, and the master station that receives the signal from the slave station regenerates and amplifies the signal. Because it is configured to transmit to slave stations, the response speed is extremely fast even in a dendritic transmission network, and the transfer circuit between the transmission line and the transmission line is the same as the conventionally commonly used semi-fixed transmission or reception circuit. It is possible to provide a remote monitoring and control device that can be adjusted to the desired level and has reliability equivalent to that of the conventional polling method.

[Brief explanation of drawings]

Fig. 1 is a block diagram of one embodiment of the remote monitoring and control device according to the present invention, Fig. 2 is a time chart for explaining the operation, Fig. 3 is a block diagram of another embodiment of the master station, and Fig. 4 is a block diagram of the main station. FIG. 5 is a diagram illustrating a configuration example of a conventional remote monitoring and control device, and FIG. 6 is a diagram illustrating the configuration of one station. 10...Master station 11-1t...Slave station 21
~2m...Slave station kyu~kn...Slave station 101.
114.214... Transmitter/receiver 101.111,2
11...Modulator 102.112,212...Demodulator 105.115,215...AGC 103,113,213...Coupling transformer 106.1
07...OR circuit patent applicant Toshiba Corporation Patent attorney Nori Ishii Figure 1 Figure 1 Child station - Master station Parent station - Te station Figure 2 (b) Figure 4 Figure 6 Import of procedural amendments Illusion February 2, 1980 Commissioner of the Japan Patent Office Black 1) Akio Yu 1, Display of the case 1985 Patent Application No. 296626 2, Name of invention information transmission system 3, Relationship with the amendment person case Patent application Personal address: 72-4 Horiyo-cho, Saiwai-ku, Yozaki-shi, Kanagawa Prefecture Agent address: 1-1-2 Azabudai, Minato-ku, Tokyo 106 Japan
No. 0 Te1. (03) 586-5556 ”',
',,, '; 5. Date of amendment order Full text of the amendment specification 10 Name of the invention Information transmission system 2. Claims (1) A control center device and a plurality of controlled center devices are connected by a transmission path, Each of the controlled station devices is connected to the transmission path in a branching manner, and the control center device and the controlled station device include a transmitter that sends out a transmission signal, and a modulator that modulates the transmission signal, and the transmission path is transmitted. In an information transmission system comprising at least a demodulator that demodulates a signal and a receiver that receives the demodulated signal, the information transmission system receives a transmission request signal from a transmitter of the control center device and a modulated signal from each of the controlled center devices. A logical sum means is provided for inputting the carrier detection signal generated when the signal is transmitted, and the output of the logical sum means is provided as a new transmission request signal to the modulator of the control center equipment, and the output of the logical sum means is provided as a new transmission request signal to the modulator of the control center equipment. When the control center device receives the signal, the control center device transmits the carrier signal to all the controlled center devices, and when the other controlled center devices that are not transmitting start transmitting, the control center device transmits the carrier signal. If there is a carrier signal on the transmission path, the controlled device starts transmitting, and if there is a carrier signal, it recognizes that another station is transmitting, and the controlled device starts transmitting based on the above conditions. After that, the information transmission system continues to transmit regardless of the presence or absence of the carrier signal. (2) Another set of OR circuits different from those described above is provided, and as inputs to the OR circuit, modulated pulse input signals from the transmitter of the control center equipment and signals received from the controlled center equipment via the demodulator are provided. 2. The information transmission system according to claim 1, wherein the output of said OR circuit, which is generated by providing a demodulated pulse output signal, is provided as a modulated pulse input to a demodulator. (3) The information transmission system according to claim 1, characterized in that when there is a pair of transmission paths, the modulation frequencies on the control center side and the controlled station side are different. (4) The information transmission system according to claim 1, wherein the transmission level of the master station is set to the maximum level. (5) The information transmission system according to claim 1, wherein the transmission level of each slave station is adjusted by semi-fixed adjustment means. 3. Detailed Description of the Invention [Object of the Invention] (Field of Industrial Application) The present invention relates to an information transmission system, particularly a control center device (
The present invention relates to an information transmission system in which a plurality of controlled station devices (hereinafter referred to as slave stations) are controlled from a master station (hereinafter referred to as a master station). (Prior art) For example, in a supervisory control system, a method of controlling multiple slave stations from one master station is generally called a 1:N configuration control method, and Fig. 4 shows an example of the configuration of this method. It is. This configuration is often employed when monitoring and controlling a pole switch or an underground switch installed on the It line. Further, this configuration is characterized in that one or two pairs of transmission lines are branched in the middle in a multi-drop manner, and each slave station is connected to this branched transmission line. That is, master station 1
Transmission path from 0. is multiple transmission paths, ,L. ...branched to Lk, and each branched transmission line 1'1
m'Q sLk, each slave station 11...1t, 21...
・2m,...kn are connected to... In this case, the signal transmitted from the master station 10 must be received by all slave stations at a normal reception level via each branched transmission path, and the signal from each slave station must also be received normally. level and must be received by the master station. The transmission method employed in this type of configuration is generally a polling method. In the polling method, the master station gives "transmission permission" to the slave stations in turn, and the only slave station that receives permission transmits data. This is a method in which the transmission data is transmitted to the slave station after the transmission from the slave station is completed. As a result, interference on the transmission path can be prevented. However, even if the slave station generates information that it wants to notify to the master station, there is a drawback that the information cannot be transmitted to the master station until the slave station receives a call from the master station. In this case, if the number of slave stations connected to one transmission path is large, the paging cycle becomes proportionally longer, and the response time for information also becomes longer. One way to solve this problem is to use content
) or C8MA/CD (Carrla
r 5ense, Multi-Access/Co1
There is a method called 1ision detector) method. In this method, each station that wishes to transmit information, including the master station, obtains the right to transmit on the condition that there is no other station's signal (carrier) on the transmission path, and then begins transmission. . In this case, if multiple stations start transmitting tl at the same time, poor reception will occur on the receiving station side. Therefore, since the receiving station does not return a "receivable signal" to the transmitting station indicating that the signal has been correctly received, each station that has already transmitted will transmit again. At this time, the transmission times of the plurality of stations are staggered. That is, the station that starts transmission earliest obtains the right to transmit and starts transmitting, and after that transmission is completed, the remaining stations sequentially obtain the right to transmit and transmit using the same procedure. In short, in the C8MA/CD system, each station needs to be able to detect whether or not a signal from a station other than its own station is being transmitted on the transmission path. A conventional method for this detection will be explained with reference to FIG. In order to simplify the explanation, FIG. 5 shows a case where there are two slave stations for the master station 10, and each of these slave stations is connected to a pair of transmission lines L6s branched into two. The configuration is such that they are connected to Ll and Lt, respectively. Each station has a transmitter 104T and receivers 104R and 114T. 114R, 214T, 214R, modulator 101, 111
゜211, demodulators 102, 112, 212, branchers coupled to the transmission line, such as transformers 103, 113゜213
Each station is equipped with automatic gain controllers ACC105, 115, and 215 on the receiving side. Please note that Fig. 6 shows a modified example of the station configuration, which includes a modulator 311, a demodulator 312, a transformer 313, a transmitter 314T, and a receiver 31.
4R is equipped with a carrier detector 316. In the configuration shown in FIG. 5, modulated input signals SDO and SDI are used on the transmitting side between the transmitter/receiver and the modulator and demodulator. Sn2 and transmission request signals R8O, R8I, R82 are input, and the receiving side receives demodulated n-order signals RDO, RDI,
RD2 and carrier detection signals CDO, CDI, CD2
is delivered. Carrier detection signals CDO, CDI,
CD2 is the transmitter 104T. It is also input to 114T and 214T. Next, a case where the slave station 11 starts transmission will be described. The transmitter 114T of the slave station 11 sends a transmission request signal R8I to the modulator 111 under the condition that there is no carrier detection signal CDI from the demodulator 112, that is, based on the recognition that no other station other than the local station is transmitting. Output. Next, the carrier of the local station 11 is modulated by the modulated input signal SDI, and outputted to the transmission path L1 at a specified level via the transformer 113. At this time, slave station 1
The master station 10 other than 1 and the other slave stations 21 transmit the signal attenuated according to the distance of the transmission path from the slave station 11 to the transformer 1.
03°213, and sends this to ACC105,
215. Just in case the received signal is attenuated,
It is amplified to a specified level by AGC and then sent to demodulator 102.
．． 212. The demodulator 102゜212 outputs carrier detection signals CDO and CD2, and the demodulated output S
DO and Sn2 are also output at the same time. On the other hand, the receivers 104R and 214R each perform reception processing on the condition that the carrier detection signal is present and the demodulated outputs SDO and Sn2 are present. Considering the master station 10, the information received from the slave station 11 is directed to the own station, and then a recognition signal indicating that this information has been correctly received is sent to the modulator 101 and the transformer 1.
03 to all slave stations. The primary slave station 21 recognizes that another station is transmitting and does not perform any processing. On the other hand, when the slave station 11 receives the recognition signal from the master station 10, it recognizes that the information from itself has been correctly transmitted to the master station, and ends the transmission process. In this case, slave station 11 becomes master station 1.
If the recognition signal from 0 cannot be received correctly,
The slave station 11 performs the transmission process again. In this information transmission system, the absence of a carrier on the transmission path may be detected almost simultaneously between the master station and the slave stations, or between the slave stations, due to a carrier detection delay. When the two stations start transmitting based on this detection, the transmitted signals will collide with each other on the transmission path. In this case, the receiving side cannot receive the data correctly, so the above operation is repeated and the transmission process is performed again. During this retransmission, each transmitting station starts transmitting at a predetermined time difference, so there will be no collision again. The above is an explanation of the basic operation. (Problems to be Solved by the Invention) In the case of the conventional device having the above configuration, a difference occurs in the reception level depending on the connection position of each station. In other words, when a signal is transmitted from a slave station connected to the end of a transmission path, the reception level at the slave station connected to the end of another transmission path is significantly different from that at the slave stations and master station connected in the middle. . As a countermeasure, each station must be equipped with an AGC for automatic adjustment, which is technically difficult. In this case, if the reception level of the signal is too low, the difference from noise in the transmission path will be small, and as a result, the signal cannot be received correctly. In short, there is a limit to the transmission distance with conventional devices. Further, in FIG. 6, the AGC in each station is omitted, and a carrier detector 316 for detecting only the medium signal is connected in parallel to the demodulator 312 in seven generations. In this case, whether or not another station is transmitting is determined based on the presence or absence of the carrier detection signal CD' output from the carrier detector 316, but as described above, there is a limit to the transmission distance. The present invention has been devised to solve the above-mentioned problems, and it is an object of the present invention to provide an information transmission system in which restrictions on the distance of a transmission path and the number of branches of a transmission path are reduced. [Structure of the invention] (Means and effects for solving the problem) In the present invention,
The frequency of the signal transmitted from the master station to the slave station and the frequency of the signal transmitted from the slave station to the master station are set in advance to be different, and when the master station receives a signal from the slave station,
The master station forms a transmission request signal based on this received signal, gives this transmission request signal to the modulator, and transmits it to all slave stations using the frequency assigned to the master station. This is to make you aware of something. (Example) An example will be described below with reference to the drawings. FIG. 1 is a block diagram of an embodiment of an information transmission system according to the present invention. In FIG. 1, the same parts as in FIG. 5 are given the same reference numerals, and the explanation thereof will be omitted. The difference between this embodiment and the conventional configuration shown in FIG. 5 is that AGCi is deleted from each station 10, 11.21 including the master station;
In the case of the pair of transmission line configuration shown in FIG.
The modulation frequency was set to 11 (
When the master station 10 detects the modulated wave f from the slave station 11.21 at the demodulator 102, the master station Each slave station 11
．． It has a configuration that can send out a modulated wave f1 (a modulated wave on which no specific signal is carried) to 21. As a means for this purpose, the master station uses logic between the transmission request signal R8O from the transmitter 104T in its own station, the modulated wave f from the slave station detected via the demodulator 102, and the double signal signal and the signal detection signal CDO. The configuration is such that the sum signal R8O' is input to the modulator 101 as a transmission request signal. The other configurations are the same as in FIG. 5. FIG. 2 is a time chart for explaining the operation, in which the left side of the dashed-dotted line shows the state when data is transmitted from the slave station to the master station, and the right side shows the state when data is transmitted from the master station to the slave station. First, a case where transmission information is generated from the slave station 11 to the master station 10 will be described. The slave station 11 uses the demodulator 11 before time t0.
When it is confirmed by the carrier detection signal CDI from 2 that there is no carrier from another station on the transmission path, it outputs the transmission request signal R8I at time t0. As a result, a modulated wave CRf is generated in the modulator 111 and passed through the coupler 11 to the transmission path.
, will appear◎. Next, the master station 10 receives the modulated wave C from the slave station 11 at time t.
Rf, is recognized by the carrier detection signal CDO of the demodulator 102 (2), the OR circuit 106 immediately outputs the transmission request signal R8O' (2), and based on this, the modulated wave CRf1 is outputted from the modulator 101 to the transmission path (2). Thereafter, in the slave station 11, the modulator 111 forms a modulated wave OR/, based on the modulated input signal SDI from the transmitter 114T, and transmits this modulated wave to the master station 10. In this case, the slave station 11 that is transmitting and the slave station 21 that is not in the transmitting state each receive the modulated wave CR/1 from the master station 10, and at time t.
In , the slave station 11 outputs the carrier detection signal CDI (2), and the slave station 21 outputs the carrier detection signal CD2' @. At this time, the slave station 11 that is currently transmitting continues to transmit, but the slave station 21 that is not in the transmitting state recognizes that another station is transmitting and does not perform its own transmission. When the slave station 11 finishes transmitting at time t, the carrier detection signal CDO of the master station 10 turns OFF', and therefore the transmission request signal R8O' also turns OFF.
The output of Rf1 is also stopped. Next, the case where the master station 10 transmits to a predetermined slave station or all slave stations will be explained. When the master station 10 confirms that there is no carrier from another station on the transmission path using the carrier detection signal CDO from the demodulator 102 before time t6, the transmitter 104T of the master station 10 outputs a transmission request signal R8O at time t6. Then, this is outputted to the modulator 101 via the OR circuit 106 as a transmission request signal 88σ. As a result, the modulated wave cl from the master station 10 is output from the modulator 101 to the transmission path via the coupler 103'. At time t, each slave station 1
1°21 is the carrier detection signal CDI, CD2
Also, the transmitters 114T and 214T use a built-in sequence circuit (not shown) to detect when the other station is transmitting, depending on the condition that the own station is not transmitting, that is, there is no transmission request signal R81'E or R82. It recognizes that there is a problem and does not transmit from its own station. Then time t? At the master station 1
Each slave station 11, 21 receives a signal modulated by the modulated input signal SDO from SDO. Then, at time t, the master station 1
When transmission from 0 is completed, no carrier exists on the transmission path at all. As is clear from the above description, by simply adding a circuit to the master station 10, the AGC circuit can be omitted, and the carrier detection circuit can also be omitted. Further, the transmission level of each slave station is semi-fixedly adjusted in advance so that the reception level is the same. In this case, the transmission level of the master station is the maximum level, and each slave station can be semi-fixedly adjusted to the reception level according to the loss on the way, making maintenance easier and reducing noise. It is possible to prevent malfunctions caused by such factors. Figure 2) is a detailed diagram of the modulated input signal, and the inside of the /gus signal is f+ for the center frequency f.
+Δf or! +-Δf. FIG. 3 is a block diagram of another embodiment of the master station. In this embodiment, the demodulated output RDO and carrier detection signal CDO received from the slave station are also detected by the OR circuits 107 and 108, and sent to the modulator 101 as the transmission request signal R8O' or SD.
It is a good idea to give it as O'. As a result, any station can correctly receive signals from other stations. In the above embodiment, the master station and the slave station are connected by a pair of transmission paths, and different and identical waves are transmitted to the master station and the slave station, respectively, but the present invention is not limited to this. The present invention can be applied not only to electrical signal paths but also to information transmission systems using optical signal paths. Further, the OR circuit in the above embodiment is a general MODEM
Since MODEM has a 2-input and 2-output terminal configuration, 9 items are provided, and MODEM f: may be omitted if a different item is used. [Effects of the Invention] As explained above, according to the present invention, the transmission frequency is changed and assigned from the master station to the slave station or from the slave station to the master station, and the master station that receives the signal from the slave station uses the frequency of the master station. Since the structure is configured so that the transmission is transmitted to other slave stations by using It is possible to provide an information transmission system that can be adjusted to a semi-fixed transmission or reception level and has reliability equivalent to that of the conventional polling method. 4. Brief description of the drawings FIG. 1 is a block diagram of one embodiment of the information transmission system according to the present invention, FIG. 2 is a time chart for explaining the operation, and FIG. 3 is a block diagram of another embodiment of the master station. FIG. 4 is a system diagram showing the connection relationship between a master station and a slave station, FIG. 5 is a configuration example diagram illustrating a conventional information transmission system, and FIG. 6 is a side view of the configuration of one station. 10...Master station 11-1t...Slave station 21
~2m...Slave station k1~kn...Slave station 104T
, 114T, 214T... transmitters 104R, 114R
, 214R...Receiver 101.111.211...
Modulator 102.112.212...Demodulator 103', 113', 213'...Brancher 106.1
07...OR circuit patent applicant Toshiba Corporation Patent attorney Norio Ishii Figure 1 Figure 3 Figure 6 Foil Figure 5

Claims (3)

[Claims] (1) One or two pairs of control center equipment and multiple controlled equipment
Each of the controlled station devices is connected to the transmission path in a multi-drop manner, and the control center device and the controlled station device have a transmitter that sends out a transmission signal, and a transmitter that modulates the transmission signal. A remote monitoring and control device comprising at least a modulator that demodulates a transmitted signal, a demodulator that demodulates a transmitted signal, and a receiver that receives a demodulated signal. A sum circuit is provided, and the input to the OR circuit is a carrier detection signal received via a demodulator of the transmission request signal from the transmitter and the modulation signal from each of the controlled station devices, and When the output of the circuit is connected as a new transmission request signal of the modulator and the modulated signal from the controlled station device is received by the control station device,
The control center device transmits a carrier signal to all controlled center devices, and when another controlled center device that is not transmitting starts transmitting, it detects the presence or absence of the carrier signal, and the carrier signal is transmitted. The controlled device starts transmitting when there is no carrier signal, and recognizes that another station is transmitting when there is a carrier signal, and after the controlled device starts transmitting under the above conditions, regardless of the presence or absence of the carrier signal. A remote monitoring and control device characterized in that it continues transmitting without any interruption. (2) Another set of OR circuits different from those described above is provided, and the inputs of the OR circuit are the modulated pulse input signal from the transmitter of the control center equipment and the input signal from the controlled center equipment via the demodulator. 2. The remote monitoring and control device according to claim 1, wherein the received demodulated pulse output signal is output, and the output of the OR circuit is connected as a modulated pulse input of a demodulator. (3) The remote monitoring and control device according to claim 1, wherein when there is a pair of transmission paths, the modulation frequencies on the control center side and the controlled station side are different.