JP2001230708A - Power line data transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To construct a highly reliable local area network suitable for data transmission by power line carrier. SOLUTION: In this power line data transmission system for transmitting data between plural power line carriers connected to a power line by using the power line as a signal transmission line, a transmission phase cycle synchronized with a power line voltage wave 9 is determined, different plural specified phases in the transmission phase cycle are respectively allocated to the plural power line carriers as transmission start phases and the respective power line carriers start the transmission of messages from the transmission start phases allocated to themselves.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a power line data transmission system for transmitting meter reading data and other data by using a power line such as a distribution line as a signal transmission line.

[0002]

2. Description of the Related Art A power line has much noise generated by a load connected to the power line, and also has a large attenuation in a high frequency band used for signal transmission due to the influence of the load. For this reason, the power line is not a good transmission line, but using the already wired power line has the advantage that there is no need to lay a new signal transmission line. , Such as ON / OFF control of contacts, which can be used even when the transmission speed is low.

For data transmission, a coaxial cable,
In general, a dedicated line such as an optical cable is used as a transmission line. IEEE 802.3 is a typical data transmission method.
There is a compliant LAN. In this LAN, CSMA / C
D (Carrier Sense MultipleAccess / Collision Detecti
on) Transmission control is performed by the method. The transmission device that has received the data to be transmitted from the information device performs transmission if it confirms that no carrier exists on the transmission path. Monitors the voltage of the transmission line during transmission.If the voltage is out of the specified range, it is determined that the transmission has collided with another transmission, and the transmission is stopped. And then resend. Other transmission devices on the transmission path normally receive the data on the transmission path, and when the data is addressed to its own address or the broadcast address, transfer the data to the information device. LA conforming to IEEE802.3
N is the transmission speed, line length,
By limiting the number of transmission devices, transmission path characteristics that enable high-speed transmission are maintained, and the absence of collision in transmission means that data is correctly transmitted to the other party, and the reception response from the other party is Do not need.

In recent years, information devices such as personal computers have become widespread not only in offices but also in households, and various local area networks have been actively constructed. Under such circumstances, attention has been paid to power line carriers that can transmit signals without wires, and local area networks using power line carriers have been studied.

[0005] In the power line carrier, transmission line characteristics must be improved in order to perform high-speed transmission corresponding to information equipment, but between a load connected to the power line and the power line transmission line, there is a problem.
It is known that transmission line characteristics can be improved by inserting a blocking filter (FIG. 19) that allows passage of commercial power frequencies and attenuates signals in a high-frequency signal band. In FIG. 19, L1 and L2 are coils, and C1 is a capacitor.

[0006] In other words, by inserting a blocking filter into a load that significantly deteriorates transmission path characteristics, high-speed transmission by power line carrier becomes possible. According to the current Radio Law, a band of 10 kHz to 450 kHz can be used, and the transmission speed is not limited as long as it is used in a range separated from other power lines by a blocking filter. In order to reduce the size of the blocking filter, transmission of 100 kbps or more is possible even if the band used is limited to 200 kHz or more.

[0007]

However, when performing data transmission, it is necessary to employ not only high-speed signal transmission but also transmission control corresponding to data transmission. In a LAN conforming to IEEE802.3, which is a typical data transmission system, transmission control is performed according to the CSMA / CD system. However, in a power line carrier, since a signal is greatly attenuated, whether a carrier exists on a transmission path. Even if you can judge whether
It is difficult to detect a collision. In addition, even if the load does not normally generate noise, noise that has a significant effect on the transmission line can be generated momentarily when the power is turned on / off or when the operation mode is switched. Since it is not practical to insert a blocking filter into the load, it is necessary to perform retransmission control based on the presence or absence of a reception response from the transmission destination in order to ensure reliability suitable for data transmission. In power line carrier with large signal attenuation, the preamble preceding the head or data of the transmission signal must be longer than the preamble of the baseband transmission by the dedicated line for gain control, etc. If necessary, there is a problem that the data transmission throughput is significantly reduced. In the case of a broadcast address,
There is also a problem that it is more difficult to confirm the reception response in a short time.

(Object of the Invention) An object of the present invention is to solve the above-mentioned problems and to provide a power line data transmission system capable of constructing a highly reliable local area network suitable for data transmission by power line carrier. It is.

[0009]

To achieve the above object, according to the present invention, a power line is used as a signal transmission line, and data is transmitted between a plurality of power line carriers connected to the power line. In a power line data transmission system performing transmission, a transmission phase cycle synchronized with a power line voltage wave is determined,
A plurality of different specific phases in the transmission phase cycle are respectively assigned to the plurality of power line carrier devices as transmission start phases, and each of the power line carrier devices starts transmitting a message from the transmission start phase assigned to itself. It is characterized by having done.

The present invention described in claim 2 is the same as the claim 1.
In the power line data transmission system according to the above, each of the power line carrier devices transmits a carrier wave from the transmission start phase assigned to itself as a reception response when a self-addressed message is normally received. It is.

Further, the present invention described in claim 3 is based on claim 1.
In the power line data transmission system described above, each of the power line carrier devices holds a connection list indicating a power line carrier device connected in one local area network, and controls retransmission according to the connection list. It is characterized by the following.

[0012]

FIG. 1 shows an example of a local network according to the present invention. The range divided by the power line blocking filter 1 or the power transformer 2
4, power line carriers 5 a to 5 g connected to the respective transmission lines 3 and 4, and power line carriers 5 a to 5 c and 5
Information devices (personal computers) 6a to 6c and 6d to 6g that exchange data through d to 5g constitute a local area network 7 by the transmission path 3 and a local area network 8 by the transmission path 4.

The power line carriers 5a to 5g are
Data transmission is performed using a power line in response to a data transmission request from a to 6g. The number of power line carriers connected to one transmission line 3 or 4 is limited in advance. Here, a description will be given assuming that the limited number is 30. For the power line carrier used, different 0, 1, 2, ...,
One of addresses 28 and 29 is set. Then, as shown in FIG. 2, a half wavelength (both positive and negative) of the power line voltage wave 9 is set as one transmission phase cycle, and as shown in FIG. The transmission phase is assumed to be a transmission phase of a power line carrier having addresses 0 to 29 at equal intervals of 6 degrees. That is, address × 6 degrees =
Since the transmission start phase is set, for example, the transmission start phase of the power line carrier having the address 4 is 24 degrees. When the power frequency is 50 Hz, 1.333 ms from the zero cross, and when the power frequency is 60 Hz, the time is 1.1 from the zero cross.
It is 11 ms. In addition, one cycle of the transmission phase may be set to 1 / integer multiple of a half wavelength of the power line voltage wave 9.

Here, a case is considered in which the power line carrier having the address 4 transmits a message to the power line carrier having the address 25. The power line carrier having the address 4 must have no carrier on the transmission line by two cycles of the transmission phase (one cycle of the power line voltage wave 9) and the transmission start phase corresponding to its own address in the next one phase of the transmission phase. Then, as shown in FIG. 4, the transmission of the transmission data of the transmission data is started from the transmission start phase of 24 degrees. 0-6 degrees and 174 in the transmission phase cycle even after sending the message
The transmission is terminated by controlling the carrier wave output so as not to terminate the transmission within 180 degrees. The power line carrier on the receiving side having the address 25 receives the transmission start phase 150 corresponding to its own address in the next transmission phase cycle after the reception of the message as a reception response when the message is normally received.
A carrier wave is transmitted as a reception response signal between the next transmission start phase and the next transmission start phase of 156 degrees. Address 4
If the power line carrier having the address 25 detects a carrier wave on the transmission path between 150 degrees and 156 degrees, it recognizes that the power line carrier having the address 25 has received the message normally. Since the reception response can be confirmed by receiving only the carrier wave, the reception can be confirmed in a short time.

As shown in FIG. 5, for example, the structure of the message includes a header section, a data section, and an error detection section. The header section includes a source address, a destination address, and the like.
The power line carrier device that has received the message transmits a carrier wave as a reception response signal when the transmission destination address is its own address or a broadcast address.

The power line carrier having the address 4 cannot detect a carrier (reception response signal) on the transmission line between 150 degrees and 156 degrees in the transmission phase cycle following the transmission phase cycle in which the message transmission has been completed. in case of,
Without waiting for two transmission phase cycles, the same message is retransmitted from the transmission start phase 24 degrees corresponding to the own address in the next transmission phase cycle of the transmission phase cycle in which no response was confirmed, and if there is no response, Retransmission may be performed a preset number of times.

The power line carrier having the address 4 can detect the carrier on the transmission path between 150 degrees and 156 degrees in the transmission phase cycle following the transmission phase cycle after the completion of the message transmission, and If there is data to be continuously transmitted to the power line carrier, the transmission start phase corresponding to the own address in the next transmission phase cycle after the transmission phase cycle in which the reception response has been confirmed can be performed without waiting for two transmission phase cycles. Alternatively, continuous transmission of different telegrams may be performed by a preset number of times.

The power line carrier having the address 4 transmits continuously to the power line carrier having the address 25 or another address after performing the continuous transmission a preset number of times. Detecting that there is no carrier on the transmission path by the transmission start phase corresponding to the own address in one cycle of the transmission phase of
Message transmission is started from a transmission start phase of 24 degrees corresponding to the own address.

The transmission control is performed as described above. However, except for the case of retransmission or continuous transmission, the detection of the absence of a carrier in two transmission phases during the first transmission is performed in one transmission phase. This is because, if there is no reception response, the transmission is transmitted to another power line carrier having a higher transmission start priority, so that retransmission cannot be continuously performed.

0 to 6 degrees and 17 in the transmission phase cycle
The reason why the transmission end prohibition section is set to 4 to 180 degrees is that if the message is ended between 0 to 6 degrees, it becomes unclear which transmission phase cycle the transmission side ended on the receiving side.
This is because if the telegram is terminated within 180 degrees, the power line carrier having a transmission start phase of 0 degrees may fail to respond. In addition, when performing transmission after performing a predetermined number of continuous transmissions, detecting that there is no carrier in a transmission phase of three cycles or more is performed by positioning the transmission priority at the lowest position. This is to prevent a power line carrier having a low transmission rate from being unable to transmit.

Although the data transmission method for specifying the destination has been described above, the same method as the above-described data transmission method may be applied to data transmission to a broadcast address for transmitting data to all the connected power line carriers.
Even if the reception response signals are returned from all the power line carriers during one cycle of the transmission phase in which the reception response is expected, since they are located at different phases, there is no collision.
Even in broadcast transmission, reception can be confirmed in a short time.

However, the power line carrier on the transmitting side cannot perform retransmission control unless it knows what power line carrier is connected on the transmission path. Therefore, each power line carrier holds a connection list in which connectable power line carriers are registered.
For example, if there are four power line carriers having addresses 6, 11, 20, and 27 in one local area network, and the power line carrier at address 6 transmits a message addressed to a broadcast address, as shown in FIG. As shown in the figure, there is a reception response from the power line carrier at the addresses 11, 20, and 27, but of course, there is no reception response signal at the phase corresponding to the other addresses. Thus, address 6
The power line carrier device confirms the other connected power line carrier devices, creates and holds a connection list.

FIG. 7A shows a basic connection list in the case of the above example. It is better that the connection list is automatically created in order to flexibly cope with addition and deletion. The connection list automatic creation method is a method in which a connection confirmation message addressed to a broadcast address is transmitted when the power line carrier is started, and the connection list is automatically registered in response to the reception response. In this case, the data portion of the message to be transmitted may be empty. Also, at a preset time interval, a connection confirmation message addressed to the broadcast address is transmitted, and the connection list is automatically registered and updated based on the reception response. When there is no registration in the connection list, the automatic registration of the connection list may be repeatedly performed. Also, in the data transmission / reception of data transmission, when a message from a power line carrier that is not registered in the connection list is received normally, the power line carrier is registered in the connection list, and retransmission is performed a preset number of times. If the received response after transmission of the message cannot be confirmed even after retransmission, the unresponsive power line carrier is deleted from the connection list. By these operations, the state of the power line carrier connected to the transmission path can be kept up to date. Further, as shown in FIG. 7B, the connection list is advantageously weighted according to the presence or absence of a response.

When the power line carrier automatically starts registration of the connection list at the time of startup, if a carrier wave is detected at the transmission start phase corresponding to the own address as a reception response at that time, a display notifying an abnormality is displayed. If functions other than display are stopped, it is possible to prevent confusion of the system due to address duplication.

When transmitting a large amount of data, retransmission control is more efficient if a plurality of packets are transmitted at once and a reception response is returned for each packet, instead of increasing the amount of data transmitted at one time. . Even in the case of the present invention, if the number of devices to be used (integer) is limited to M / N (M: maximum number of connected devices, N: number of packets), N packets can be transmitted at one time. 4 when up to 30 units can be connected
Let's consider a case where it is used only on a stand. The number N of packets at this time is 7. The addresses of the four power line carriers to be used are set to 0, 7, 14, 21. It is also set that the number of used power line carriers is limited to four. This makes it possible to transmit seven packets at once.

Here, as shown in FIG. 8, it is assumed that the power line carrier having the address 7 transmits a message to the power line carrier having the address 21. The power line carrier having the address 7 starts transmission after detecting that there is no carrier on the transmission path by the transmission start phase 42 degrees corresponding to the own address in the transmission phase 2 cycles or more and the next transmission phase 1 cycle. From the phase, transmission of a message consisting of seven packets starts. Even after sending the message, the transmission is terminated by controlling the carrier wave output so as not to terminate the transmission between 0 and 6 degrees and 174 and 180 degrees in the transmission phase cycle. The power line carrier having the receiving side address 21 has a reception status of seven packets of XX
(○ indicates normal reception, × indicates abnormal reception), the transmission start phase corresponding to the own address in the next transmission phase cycle after the transmission phase cycle in which the signal transmission of the received message has been completed is performed at intervals of 6 degrees. In the seven phase intervals of
The carrier is transmitted as follows: × ○ ○ × (○ is transmitted, × is not transmitted). Thus, the power line carrier having the address 7 can recognize the reception status of each packet of the power line carrier having the address 21. This multiple packet batch transmission method is also effective for a message addressed to a broadcast address.

As shown in FIG. 9, each power line carrier includes a power line coupling circuit 11 connected to a power line via a power line connection terminal 10, a transmission phase detection circuit 12 for detecting a phase in a transmission phase cycle, Carrier detection circuit 13 for detecting the presence or absence of a carrier, a signal transmission control circuit 14 for transmitting a transmission data signal, a connection confirmation signal, a reception response signal, and the like, an output amplification circuit 15, a gain control for changing the level of the received carrier. A circuit 16; a carrier unit 18 comprising a signal modulation / demodulation circuit 17 for modulating a carrier wave to be transmitted and demodulating a received signal; and a control unit 1 such as a CPU.
9, an external interface unit 21 connected to an information device (FIG. 1) via an external connection terminal 20, and a display unit 22.
, A setting unit 23, a timer 24, a memory 25, and a power supply unit 26. The display unit 22 is configured with an LED or the like, and displays a status such as transmitting or receiving, an abnormal display such as no connection list registration, address duplication, and other displays. The setting unit 23 includes a manual switch for setting an address and the like. The timer 24 has a function of notifying the control unit 19 of the automatic update time of the connection list and the like. The memory 25 stores its own address, connection list, data, and the like.

As transmission control, a carrier wave can be detected in one transmission start phase section (for example, a phase of 0 to 6 degrees in the case of address 0), and a carrier wave is transmitted in one transmission start phase section. Therefore, the power line carrier not only transmits and receives signals for high-speed transmission, but also transmits and receives amplitude modulated signals using the same carrier and having a modulation section equal to one transmission start phase section. It can be carried out. This amplitude modulation signal may be used as communication means such as a backup at the time of retransmission. For example, a half wavelength of the power line voltage wave 9 is set as one transmission phase cycle, and
When each of the divided transmission start phase sections is assigned to the power line carrier device having the address of address 0 to 29, transmission / reception of an ASK signal having a modulation section having a length equal to the transmission start phase section is not added to the apparatus. Can be realized. That is, in FIG. 9, a carrier is modulated by turning on / off a switch of the signal transmission control circuit 14 in accordance with data to be transmitted to generate an ASK signal, which is injected into a power line. When receiving, the signal is demodulated by the carrier detection circuit 13. For example, when transmitting a message by the ASK signal from the power line carrier at address 8 to the power line carrier at address 20, the result is as shown in FIG. The data transmission according to the present invention described above with reference to FIG. 4 is performed at a transmission speed of 100 kbps or more using, for example, a PSK signal, while the data transmission using the ASK signal described with reference to FIG. If a half wavelength is divided into 30, the transmission speed becomes 3 kbps. 3 kbps if you want to give priority to speed over speed
ASK signal is used for data transmission. Note that the modulation section of the ASK signal may be set to an integral multiple of the transmission start phase section. In that case, the transmission speed is 1 / integer multiple of 3 kbps.

As a system configuration, there are cases where different transmission paths are desired to be treated as the same area network. That is, a general power line is wired with a single-phase three-wire outdoors and divided into a red phase and a black phase indoors, and it is desired to treat the indoor red phase and black phase as the same area network. Alternatively, when all the power line carriers cannot communicate with each other when the transmission path is long, if the transmission path is separated by using a blocking filter, it is desired to treat these transmission paths as the same area network.

For example, as shown in FIG. 11, a power line carrier at addresses 1, 4, and 9 is connected to a black phase of a single-phase three-wire indoor wiring separated from an outdoor wiring by a blocking filter 1 and a red phase. When the power line carrier devices at addresses 14, 20, and 27 are connected to each other, communication cannot be performed between power line carrier devices having different phases. (The actual signal leaks to other phases but is not suitable for practical use because it is extremely attenuated.) In such a case, the transport unit 1 connected to the black phase
8a, the transport unit 18b connected to the red phase, and the control unit 19
And a power line carrier bridge device 27 which has one address (for example, 11), a connection list of black phase and red phase, and transfers signals between different phases.

As shown in FIG. 12, if the power line carrier at address 1 and the power line carrier at address 27 cannot communicate with each other stably due to severe signal attenuation due to the long length of the indoor wiring, it must be ensured. In order to secure an area in which communication can be performed, a blocking filter 1b may be unavoidably inserted on the way to delimit the transmission path. In such a case as well, the power line carrier bridge device 27 is used to connect the carriers 18a and 18b to the indoor wiring on both sides of the blocking filter 1b.

When a message received from a certain transmission line is a message addressed to a power line carrier registered in a connection list of another transmission line, the power line carrier bridge device 27 replaces the power line carrier. A response is received, and the message is transmitted to the target transmission line. If the message received from a certain transmission line is a message addressed to a broadcast address, a reception response is performed in place of all the power line carriers registered in the connection list of another transmission line, and the broadcast address is addressed. Send a message to another transmission line. Also, in order to prevent transmission from being repeated in a loop between different transmission paths, a message addressed to the broadcast address is not transmitted to the transmission path to which the power line carrier of the transmission source address is connected. In addition, in order to simplify transmission control, the number of power line carrier bridge devices 27 that directly connect a certain transmission line to another transmission line is limited to one.

As is apparent from FIGS. 11 and 12, the power line carrier device 27 is used together with the blocking filter, so that the power line carrier device 27 can be miniaturized with an integral structure.
It becomes easy to handle. 13 shows a device 28 in which the power line carrier bridge device 27 of FIG. 11 is integrated with the blocking filter 1, and FIG. 14 shows the power line carrier bridge device 2 of FIG.
7 having an integral structure with blocking filter 1b
9 are shown respectively.

On the other hand, there is a case where it is desired to connect different local area networks. For example, connections between local area networks separated by a blocking filter for each indoor floor, or connections between indoor and outdoor local area networks, or more than the maximum number of power line carriers connected on the transmission path Sometimes, a connection between local area networks when a transmission path is divided by using a blocking filter is used. In such a case, it has a plurality of addresses corresponding to a plurality of different local area networks, and a connection list of each different local area network,
A power line carrier router for transferring a signal between local networks is used by checking the data content in the message and if it satisfies a predetermined condition. This power line carrier router device 30 is shown in FIG. Transport unit 1
The configuration is the same as that of the power line transport bridge device 27, except that the address 12 of the local network A is allocated to 8a, and the address 3 of the local network B is allocated to the transport unit 18b, and the message configuration is different. The message structure is as shown in FIG.

Consider a case where the power line carrier at address 5 of the local area network A transmits a message to the power line carrier at address 5 of the local area network B. The transmission destination address of the header part of the message is the address 12 of the carrier 18a of the power line carrier router device 30, the flag of the data part of the message is 1 (set) meaning transfer to a different local area network B, and The source address is 5, which is the same as the source address in the header, and the destination address is the address 5 of the power line carrier of the local area network B. Therefore, if the flag in the data portion of the received message is 1, the power line carrier router device 30 transfers the received message to the power line carrier at the destination address 5 as it is.

Since the power line carrier router device 30 is used together with the blocking filter in the same manner as the power line carrier bridge device 27, it is easier to handle the power line carrier device if it is formed as an integral structure.

As a form in which different local area networks are connected and used, as shown in FIG.
There is a case where outdoor wiring and indoor wiring are connected. (Outdoor wiring belongs to the power company, and indoor wiring belongs to the customer,
It is better to manage them as different local area networks. In FIG. 17, PC is an information device, PLC is a power line carrier device, BF is a blocking filter, RT is a power line carrier router device, and WHM is a watt hour meter. The local area network within the customer is connected to the local area network of the outdoor wiring by a power line carrier router device (RT) for each customer A, B and C. Power line carrier (PLC) for transmitting meter reading information of a watt hour meter (WHM) to a local area network of outdoor wiring
Is connected. In the case of FIG. 17, since the blocking filter (BF), the power line carrier router (RT), and the watt hour meter (WHM) are located very close on the wiring, FIG.
As shown in FIG. 8, if these are formed into an integrated device 31, the installation space is reduced and the device is easy to handle, and the power line carrier router (RT) is equipped with a watt hour meter (WH).
The meter reading information of M) may be transmitted.

[0038]

As described above, according to the first aspect of the present invention, since transmission is started at a different transmission start phase for each power line carrier, it is possible to perform random transmission avoiding collision. Thus, a highly reliable local area network suitable for data transmission by power line carrier can be constructed.

According to the second aspect of the present invention, since the reception response signal of only the carrier is transmitted, the reception can be confirmed in a short time, and the reliability suitable for data transmission by power line transmission is improved. A high local area network can be built.

According to the third aspect of the present invention, 1
Since retransmission is controlled in accordance with the connection list of the power line carrier connected to one local area network, retransmission can be reliably controlled.

[Brief description of the drawings]

FIG. 1 is a diagram showing a system configuration according to an embodiment of the present invention.

FIG. 2 is a diagram showing a transmission phase cycle determined in one embodiment of the present invention.

FIG. 3 is a diagram showing a transmission start phase.

FIG. 4 is a diagram showing a relationship between a transmission and a reception response when a transmission destination is designated.

FIG. 5 is a diagram showing an example of a message structure;

FIG. 6 is a diagram showing a relationship between a transmission and a reception response in the case of a broadcast destination.

FIG. 7 is a diagram showing an example of a connection list.

FIG. 8 is a diagram showing the relationship between transmission and reception response in the case of batch transmission of a plurality of packets.

FIG. 9 is a diagram illustrating an example of a circuit configuration of the power line carrier device in FIG. 1;

FIG. 10: AS used for backup and the like
FIG. 3 is a diagram illustrating a relationship between transmission of a K signal and a reception response.

FIG. 11 is a diagram showing another embodiment of the present invention when different transmission paths are treated as one local area network.

FIG. 12 is a diagram showing another embodiment of the present invention when a divided transmission path is treated as one local area network.

13 is a diagram showing a device in which the power line carrier device in FIG. 11 is integrated with a blocking filter.

14 is a diagram showing a device in which the power line carrier device in FIG. 12 is integrated with a blocking filter.

FIG. 15 is a diagram showing another embodiment of the present invention when a message is transferred between different local area networks.

FIG. 16 is a diagram showing an example of a message structure used in the case of FIG. 15;

FIG. 17 is a diagram showing another embodiment of the present invention in the case where a message is transferred between a local area network with indoor wiring and a local area network with outdoor wiring.

18 is a diagram showing a device in which the power line carrier router device in FIG. 17 is integrated with a blocking filter and a watt hour meter.

FIG. 19 is a diagram illustrating a circuit configuration example of a blocking filter.

[Explanation of symbols]

 1, 1a, 1b Blocking filter 2 Power transformer 3, 4 Transmission line 5a to 5g Power line carrier 6a to 6g Information equipment 7, 8 Local area network 9 Power line voltage wave 18, 18a, 18b Carrier 19 Controller 27 Power line carrier Bridge device 30 Power line carrier router device

Claims (3)

[Claims] In a power line data transmission system that uses a power line as a signal transmission line and performs data transmission between a plurality of power line carriers connected to the power line, a transmission phase cycle synchronized with the power line voltage wave is determined. A plurality of different specific phases in the transmission phase cycle are respectively assigned to the plurality of power line carrier devices as transmission start phases, and each of the power line carrier devices starts transmitting a message from the transmission start phase assigned to itself. A power line data transmission system, comprising: 2. The power line carrier apparatus according to claim 1, wherein each power line carrier transmits a carrier from the transmission start phase allocated to itself as a reception response when a self-addressed message is normally received. Power line data transmission system. 3. The apparatus according to claim 1, wherein each of the power line carriers holds a connection list indicating the power line carriers connected in one local area network, and controls retransmission according to the connection list. The power line data transmission system according to claim 1, wherein