JPH11266191A - Method and device for transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain securing the reliability of transmission and improvement of transmission efficiency by automatically setting the optimal transmission speed and synchronization method, according to an injection system of a signal in the same circuit and software. SOLUTION: A control circuit 11 discriminates whether or not there are a frequency and a signal of a zero-cross signal from a zero-cross circuit 7, and the specification for transmission are set. Regarding the reception processing of a signal, a demodulation signal is digital-converted by an A/D conversion circuit 8, and the control circuit 11 has process through software. With regard to transmission processing, the control circuit 11 similarly has a software processed and is modulated with a D/A conversion circuit 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission method and a transmission apparatus for performing automatic meter reading of electricity, gas, water, and the like.
In particular, the present invention relates to a transmission method and a transmission apparatus that can support any transmission method of a power line carrier using a low-voltage lamp or a dedicated line communication function using a dedicated line.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a diagram illustrating a conventional transmission device disclosed in Japanese Unexamined Patent Publication (Kokai) No. H10-26095. FIG.
, 21 and 22 are power supply terminals connected to a distribution line (electric light line), and 23 is a ground terminal connected to a ground line. 24
Is a coupling circuit for transmitting or receiving a modulation signal for performing communication, 25 is a power supply synchronization circuit for detecting a zero-cross point of a commercial power supply, and 26 is a power supply circuit for supplying power to the circuit.
27 is a receiving circuit for demodulating the received modulated signal, 28 is a transmitting circuit for modulating and transmitting a digital signal, and 29 is a CPU for performing reception control and transmission control. Reference numeral 30 denotes a switch for switching between the line injection method and the common ground line / ground return method, and reference numeral 31 denotes a relay for switching between transmission and reception.

[0003] Next, the operation of the conventional transmission device will be described. The transmission is performed by the CPU 29 so that the modulation signal can be superimposed on the commercial power from the peak of the commercial power waveform in synchronization with the timing from the power synchronization circuit 25.
This is a power supply synchronization system that outputs a transmission signal to the power supply. On the other hand, the reception is performed by the CPU 2 by the start-stop synchronization of the reception signal demodulated by the reception circuit 27 regardless of the timing from the power supply synchronization circuit 25.
9 performs a receiving process.

[0004]

In the conventional transmission apparatus, it is not a problem to adopt the start-stop synchronous reception in the joint ground line / ground return injection system which is not easily affected by noise. In this case, since asynchronous start reception is performed, reception processing is also performed at the timing when the modulated signal is affected by the power line noise or the load, and there is a problem in transmission reliability. In addition, in the joint ground line / ground return injection method, during start-stop synchronization, transmission is not performed at the optimal transmission speed, and the transmission is performed at a fixed transmission speed, resulting in poor transmission efficiency. there were.

The present invention has been made to solve such a problem, and automatically changes a synchronization method by a signal injection method, and a transmission speed in a method hardly affected by a power line noise or a load. It is an object of the present invention to provide a transmission method and apparatus that shortens the communication time by increasing the transmission time and increases the efficiency of the system.

[0006]

According to a transmission method according to the present invention, there is provided a transmission method for transmitting a modulated signal for performing communication at a predetermined speed by synchronizing with a commercial frequency power supply or by start-stop synchronization. A zero-cross signal from the commercial frequency power supply is detected, and the communication synchronization method and transmission speed are switched according to the presence or absence of the zero-cross signal.

In a transmission method for transmitting a modulated signal for communication at a predetermined speed in synchronization with a commercial frequency power supply or in a start-stop synchronization, a zero-cross signal of the commercial frequency power supply is detected, Detects a setting signal set externally according to the transmission method such as the distribution line injection method, the common ground line / ground return method, the dedicated communication method, etc., and based on the zero cross signal and the setting signal, the communication synchronization method And the transmission speed.

In the above method, when the synchronization method is start-stop synchronization, the master station determines the fastest transmission speed at which no error occurs from the response of the communication at the specified speed designated by the master station, The transmission speed is set to the highest transmission speed.

Also, the transmission speed of the transmission device is selected and set only when the transmission device is installed or when a transmission speed setting command is issued from the master station.

Further, the transmission device according to the present invention has a power supply terminal connected to a distribution line (light line), one terminal connected to the distribution line, and one terminal connected to the distribution line connected to a ground line. A coupling circuit connected to the transmission means and the reception means via a transmission / reception switching relay, a zero-cross circuit for detecting a zero-cross point of the distribution line voltage, and receiving an output of the zero-cross circuit. And a control circuit for controlling a synchronization method and a transmission speed of the transmitting means and the receiving means, and a power supply circuit connected to the power supply terminal and supplying power to the circuits and means.

In the above configuration, the zero cross circuit is connected to the secondary side of the power supply circuit.

A contact detecting circuit for detecting the short circuit and the open state of the terminal capable of setting the short circuit and the open state from the outside, outputting a signal corresponding to the short circuit and the open state, and controlling the selection of the synchronization method and the transmission speed by the control circuit; It is.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a block diagram showing a transmission apparatus according to Embodiment 1 of the present invention.
In the figure, reference numerals 1 and 2 denote power terminals for connecting distribution lines (light lines), and reference numerals 3 and 4 denote communication terminals for inputting and outputting signals for communication. 5 is a power supply circuit for supplying power to each circuit,
Reference numeral 6 denotes a coupling circuit for transmitting or receiving a modulation signal for performing communication, and reference numeral 7 denotes a zero cross circuit for detecting a zero cross point of a commercial power supply. Reference numeral 8 denotes an A / D conversion circuit that converts a received modulated signal into a digital signal, 9 denotes an injection circuit that transmits a modulated signal, 10 denotes a D / A conversion circuit that modulates a signal for transmission, and 11 denotes reception control and transmission. A control circuit that performs control, and 12 is a relay that switches between transmission and reception.

Next, the connection configuration of the transmission device will be described. When the power supply terminals 1 and 2 are connected to the communication terminals 3 and 4 and the power supply terminals 1 and 2 are connected to the distribution line, a line injection method of power line conveyance is used. When the power supply terminal 1 and the communication terminal 3 are connected to a distribution line, and the power supply terminal 2 is connected to a common ground line and the power supply terminal 2 and the communication terminal 4 are connected to a ground line, a common ground / ground return method of power line conveyance is used. . Power supply terminals 1 and 2 to distribution line,
When the communication terminals 3 and 4 are connected to a dedicated line, a dedicated line communication system is established.

Next, the transmission / reception operation will be described. The receiving process is to convert the modulated received signal received by the coupling circuit 6 to A
The digital signal is converted by the / D conversion circuit 8 and the control circuit 11
To supply. When the control circuit 11 is synchronized with the power supply, software processing is performed in synchronization with the zero-cross signal from the zero-cross circuit 7, and when the start-stop synchronization is performed, software processing is performed at an internal timing of the control circuit 11. On the other hand, in the transmission processing, the control circuit 11 switches the relay 12 to the transmission side, similarly takes a timing by software processing, outputs the timing to the D / A conversion circuit 10 to modulate the transmission signal, and transmits the signal from the injection circuit 9 to the coupling circuit 6. To transmit the modulated signal.

The operation of setting the transmission process based on the connection form and the commercial power frequency will be described with reference to the flowchart of FIG. A transmission processing setting operation is performed when an initialization program is executed when the power of the transmission apparatus is turned on. The zero-cross circuit 7 outputs a zero-cross signal synchronized with the commercial frequency in the case of line injection, but does not output a zero-cross signal in the case of the common ground line / ground return method or the dedicated line communication method. First, the control circuit 11 analyzes a signal from the zero cross circuit 7 (step 1). If there is a zero cross signal, the control circuit 11 determines the frequency of the zero cross signal (step 2). As a result of the determination, if the frequency is 60 Hz, the transmission processing of the power supply synchronous system for transmitting and receiving in synchronization with the timing of the zero cross signal at the transmission rate of 120 bps is performed (step 3). As a result of determination, if the frequency is 50 Hz, 10
The transmission processing of the power supply synchronous system for transmitting and receiving in synchronization with the timing of the zero cross signal at the transmission speed of 0 bps is performed (step 4).

The reason why the transmission rate is switched depending on whether the commercial frequency is 60 Hz or 50 Hz is that when a modulated signal is injected into a power line, the vicinity of the zero point of the commercial power is the timing that is least affected by the power line noise and the load. It is.
Therefore, the transmission speed is set to be proportional to the commercial frequency so that only the signal near the zero-cross point can be analyzed, thereby improving the transmission reliability.

If there is no zero-cross signal (step 1), it is the joint ground line / ground return method or the dedicated line communication method. In the case of this communication, the modulation signal is not affected by the power line noise and the load, so that the transmission speed is higher than 100 bps and 120 bps, for example, 12 bps regardless of the commercial frequency.
Set to 00 bps or the like. The reception method is set to the start-stop synchronization method (step 5).

Since the first embodiment is configured as described above, it is possible to automatically set the transmission speed and the synchronization method suitable for the signal injection method regardless of the connection mode.
That is, there is no need to prepare transmission devices for the power line injection system and the common ground line / ground return system, and the switching operation by the switch as described in the conventional example is unnecessary, so that an erroneous operation due to human error is possible. There is no connection, and there is no need to prepare transmission devices for 50 Hz and 60 Hz.

As means for realizing processing of transmission / reception signals, any means of an electric circuit or software may be employed. However, as described in Embodiment 1, if means by software processing is employed. Since only the algorithm (software) processed by the CPU needs to be changed using the hardware configuration described in the conventional example, it is possible to provide a transmission device that is inexpensive, versatile, and highly efficient.

Embodiment 2 FIG. FIG. 3 is a block diagram showing a transmission device according to Embodiment 2 of the present invention. In the figure, reference numerals 1 to 12 have the same configuration and the same function as those described in FIG. Reference numerals 13 and 14 denote contact input terminals that can be set to short-circuit and open from the outside, and reference numeral 15 denotes a contact detection circuit that detects contact information from the contact input terminals 13 and 14. For example, when the contact input terminals 13 and 14 are short-circuited, the contact detection circuit 15 outputs an “H” level signal, and when the contact input terminals 13 and 14 are open,
The contact detection circuit 15 outputs an “L” level signal. 7
Is a zero-cross circuit connected to the secondary side of the power supply circuit 5.

The connection is the same as that described in the first embodiment (FIG. 1). In the case of line injection, the contact input terminals 13 and 14 are short-circuited, and in the case of communal ground line / ground return or dedicated line communication, they are opened. When executing the initial setting program, the control circuit 11 determines a zero-cross signal from the zero-cross circuit 7 and a signal level from the contact detection circuit 15. When the control circuit 11 determines that the signal from the contact detection circuit 15 is at the “H” level, the control circuit 11 sets the power supply synchronous system, which is a transmission process of line injection. At this time,
The control circuit 11 determines the zero-cross signal from the zero-cross circuit 7 and sets the transmission speed to 100 bps or 120 bps.

When the control circuit 11 determines that the signal from the contact detection circuit 15 is at the "L" level, the control circuit 11 sets the circuit configuration to the start-stop synchronization system and sets the transmission speed to, for example, 120
Set to 0 bps. First Embodiment A Zero Cross Circuit 7
The connection from the secondary side of the power supply circuit 5 instead of the connection from the communication terminals 3 and 4 as in the zero cross circuit described above is omitted because the insulation with the distribution line is omitted and the zero cross circuit 7 is composed of few parts. This is to make it possible.

Embodiment 3 FIG. FIG. 4 is a configuration diagram for explaining Embodiment 3 of the present invention. In the figure, 50
Is a distribution line (electric light line) or a dedicated line, 51 is a master station for automatic meter reading, 52 is a transmission device according to the third embodiment, and 53 is a meter for measuring the amount of electricity, gas, water, or the like used.

The operation of the third embodiment for automatically setting the transmission speed to the optimum speed in the joint ground line / ground return system or the dedicated line communication system described in the first or second embodiment will be described with reference to FIG. This will be described with reference to the sequence diagram of FIG. The master station 51 and the transmission device 52 have the same function with respect to the transmission process. In the case of start-stop synchronization, the transmission speed is set to 300 bp.
s, 600 bps, 1200 bps, and 2400 bps. Also, 1
The transmission rate of 00 bps is configured to be able to always receive.

When the master station 51 determines that the transmission device 52 is of the common ground line / ground return route system or the leased line communication system when the transmission device 52 is installed, the master station 51 transmits the transmission device 52 to the transmission device 52 at a low speed of 100 bps. After transmitting a message with a designated transmission rate in a format as shown in FIG. 6 (step 10), the message is transmitted in the same format at a designated transmission rate (step 12). On the other hand, the transmission device 52
It is set so that a message at a low speed of 100 bps is received, and a message at a transmission rate specified by the message can be received. Thereafter, the master station 51 of the designated transmission speed in step 12
If the message from the client is normally received, a message in the same format is sent to the master station 51 (step 14). Master station 5
When the response from the transmission device 52 is normally received, the transmission speed in the message for designating the transmission speed at a low speed of 100 bps is sequentially increased, and the transmission device 52 operates normally (with no error). Determine the fastest transmission speed that can respond. The master station 51 transmits a message in which the code information is changed in the format shown in FIG. 6 to the transmission device 52 at the determined speed (step 16). After receiving the message in step 16, the transmission device 52 returns a response to the reception confirmation to the master station 51 (step 18). Thereafter, the master station 51 and the transmission device 52 perform transmission / reception processing at the specified transmission speed. When communication from the transmission device 52 is not normally performed for a predetermined time or longer, the master station 51 performs the same processing as Steps 10 to 18 again to reset the highest transmission speed.

According to the above-described configuration, the communication speed can be automatically set between the master station 51 and the transmission device 52, and an optimal system based on the joint ground line / ground return method or the dedicated line communication method can be realized. Can be built. Further, as described above, if the transmission speed is selected only when the transmission device 52 is installed or when a transmission speed setting command (telegram) is received from the master station 51, software is created with a simple algorithm. It is possible to increase the reliability of the device.

There are computer communication, facsimile transmission / reception, and the like as methods for automatically selecting a communication speed and performing communication. These methods aim at how to efficiently transmit data with respect to the degree of congestion of the communication path. Thus, unlike the distribution line transport of the present embodiment, there is almost no problem of communication path congestion, and the purpose is different from the purpose of the present apparatus of how to obtain high transmission efficiency without generating a transmission error. .

Embodiment 4 In the description of the third embodiment, if the communication from the transmission device 52 is not normally performed in the master station 51 for a predetermined time or more, the operation shown in FIG.
Although an example of resetting the fastest transmission rate by performing the same processing as in steps 10 to 18 of the above has been described, other methods can be used. FIG. 7 is a flowchart illustrating a transmission method according to the fourth embodiment. The other configuration is the same as that of the third embodiment, and the description is omitted. In the fourth embodiment, for example, a case will be described in which the transmission speed when communication is not normally performed is 2400 bps.

When communication from the transmission device 52 is not normally performed in the master station 51 for a predetermined time or more, that is, when a transmission error occurs (step 70), the master station 51 And low speed 100bps
Then, in the format as shown in FIG. 6, a message is transmitted at 1200 bps with the transmission speed decremented by one rank (step 72), and then the message is transmitted at the speed (1200 bps) in the same format with the designated transmission speed. I do. On the other hand, the transmission device 52 receives the message at a low speed of 100 bps, and transmits the message at the transmission speed (120
0 bps), it is determined whether or not a message from the master station 51 having a transmission speed of 1200 bps can be normally received (step 74). In step 14 of FIG. 5, the transmission device 52 sets the transmission speed to 1200 bps.
When the message of the same format is received, a response is sent to the master station 51.
Then, a message in which the transmission speed has been further decremented by one rank and designated as 600 bps is transmitted, and the determination in step 74 is made. In this way, the highest transmission speed is reset. Thereafter, transmission / reception processing is performed (step 76).

According to the above configuration, Embodiment 3
A latch circuit or memory for storing the currently transmitted transmission rate is required as compared with the case of, and the configuration or algorithm is slightly complicated, but the highest transmission rate is set in order from the lowest transmission rate. Since there is no need, the setting efficiency of the fastest transmission rate is good.

The third and fourth embodiments described above.
In the above description, the case where the master station 51 sets the fastest transmission speed when communication from the transmission device 52 is not normally performed for a predetermined time or more has been described, but a message is transmitted from the transmission device 52 to the master station 51. The maximum transmission speed may be set each time the operation is performed.

Further, since the frame length of a message transmitted by the transmission device 52 used for distribution line transport is determined according to the type of the message, the transmission speed is selected according to the type of the message. Is also good. For example, when the frame length is equal to or longer than a predetermined length, the fastest transmission rate is used, and when it is less than that, a transmission rate of 100 bps (or low transmission rate) is used. By doing so, a message that takes a long time to be transmitted is transmitted at the fastest transmission speed at which error transmission frequently occurs, and a message that originally takes only a short time is not error-transmitted (or generated). (Low frequency) transmission. With this configuration, the frequency of occurrence of error transmission is reduced, and the frequency of setting the fastest transmission speed is also reduced, so that the transmission device 52 with high transmission efficiency can be obtained.

[0034]

As described above, according to the present invention, it is possible to automatically set the transmission speed and the synchronization method according to the signal injection method according to the wiring form using the same circuit configuration and software.

In the signal injection method in which the signal is not affected by the power line, the transmission efficiency can be increased by increasing the transmission speed.

Even when the transmission speed is increased, the speed at which communication can be performed between the master station and the transmission device can be automatically set in consideration of the influence of the installation environment, and an optimum system can be constructed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a transmission device according to Embodiment 1 of the present invention.

FIG. 2 is a flowchart illustrating the operation of the first embodiment.

FIG. 3 is a block diagram showing a transmission device according to a second embodiment of the present invention.

FIG. 4 is a block diagram illustrating a third embodiment of the present invention.

FIG. 5 is a sequence diagram illustrating an operation of the third embodiment.

FIG. 6 is a diagram showing a message format for explaining the operation of the third embodiment.

FIG. 7 is a flowchart illustrating transmission explaining the fourth embodiment of the present invention.

FIG. 8 is a block diagram showing a conventional transmission device.

[Explanation of symbols]

1, 2 power terminals, 3, 4 communication terminals, 5 power circuits,
6 coupling circuit, 7 zero cross circuit, 8 A / D conversion circuit, 9 injection circuit, 10 D / A conversion circuit, 11 control circuit, 12 relay, 13, 14 contact input terminal, 15
Contact detection circuit, 50 distribution line, 51 master station, 52 transmission device.

Claims (7)

[Claims] In a transmission method for transmitting a modulated signal for performing communication at a predetermined speed in synchronization with a commercial frequency power supply or with start-stop synchronization, a zero-cross signal of the commercial frequency power supply is detected. A transmission method characterized in that the communication synchronization method and the transmission speed are switched according to the presence or absence. 2. A transmission method in which a modulated signal for performing communication is transmitted at a predetermined speed in synchronization with a commercial frequency power supply or by start-stop synchronization, wherein a zero-cross signal of the commercial frequency power supply is detected, Detects a setting signal set externally according to the transmission method such as the distribution line injection method, the common ground line / ground return method, the dedicated communication method, etc., and based on the zero cross signal and the setting signal, the communication synchronization method And a transmission speed. 3. When the synchronization method is start-stop synchronization, the master station determines the fastest transmission speed at which no error occurs from the response of the communication at the designated speed designated by the master station, and sets the transmission speed of the transmission device to the highest speed. 3. The transmission method according to claim 1, wherein the transmission speed is set. 4. The transmission method according to claim 3, wherein the transmission speed of the transmission device is selected and set only when the transmission device is installed and when a transmission speed setting command is issued from the master station. . 5. A power supply terminal connected to a distribution line (light line), a communication terminal connected to the distribution line, and one terminal connected to the distribution line connected to a ground line,
A coupling circuit connected to the transmission means and the reception means via a transmission / reception switching relay, a zero-cross circuit for detecting a zero-cross point of the distribution line voltage, and a synchronizing method of the transmission means and the reception means by receiving an output of the zero-cross circuit And a control circuit for controlling a transmission rate and a power supply circuit connected to the power supply terminal and supplying power to the circuits and means. 6. The transmission device according to claim 5, wherein the zero cross circuit is connected to a secondary side of the power supply circuit. 7. A contact detection circuit for detecting a short circuit and an open circuit of a terminal capable of setting a short circuit and an open circuit from the outside, outputting a signal in accordance with the short circuit and the open circuit, and controlling selection of a synchronization method and a transmission speed by a control circuit. 7. The transmission device according to claim 5, wherein: