KR20020087544A - A data transforming control method of power-line communication - Google Patents

Abstract

PURPOSE: A method of controlling data transmission of a PLC(Power Line Communication) is provided to continually monitor a state of the PLC before transmitting data, and to start transmitting the data under normal condition only, thereby reducing data collision. CONSTITUTION: When power is applied to a PLC modem, a microcomputer of a home appliance initializes a timer and state variables and drives a timer(S11). The microcomputer decides whether data is transceived to a PLC, and decides whether data to be transmitted exists(S12). If so, the microcomputer buffers the data to be transmitted in the PLC modem, and transmits the data to the PLC(S13). The microcomputer decides whether the data is collided with other data transmitted from other home appliance(S14). If not, the microcomputer stops the data transmission, and increases a data transmission attempting frequency by 1(S15). The microcomputer decides whether the data transmission is completed(S16). If so, the microcomputer initializes the state variables(S17).

Description

A data transforming control method of power-line communication

The present invention relates to a data transmission control method of power line communication that forms a network using a chirp signal on a power line, and in particular, by continuously detecting the state of the power line before performing data transmission through the power line and starting transmission only under ideal conditions. The present invention relates to a data transmission control method of power line communication that can reduce data collision caused by multiple products using the same line.

Power line communication (PLC), which allows users to connect to the Internet by plugging in existing electrical outlets that are connected like spider webs all over the country instead of using the Internet. There is a growing interest in power line communication technology.

Power line communication is a digital communication technology in which data is transmitted on a power line to which electricity is supplied by carrying a high frequency band communication signal of 1 to 30 MHz together with an AC power source of 50 to 60 kW entering a home.

Dedicated connection equipment, which is a kind of modem, extracts only the communication signal from the power line so that the Internet can be used. Since it uses a low power signal, it does not significantly affect the operation of general home appliances.

Therefore, home network technology that can transmit and receive various information as well as the simple control function to turn on / off home appliances at remote places by interconnecting PC, peripheral devices and home appliances in each home is becoming more active. Since any home appliance needs to use electricity, a technology using a power line would be most desirable for a home network, considering an environment where electrical outlets are installed throughout the room.

However, since power line communication shares the same high-voltage wiring line, data transmission and reception of Internet services and multiple home appliances are performed, there is a problem that data is lost due to a collision when the user uses the same at the same time.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and its object is to continuously detect the state of the power line before transmitting data through the power line and start the transmission only under ideal conditions so that a plurality of products have the same line. It is to provide a data transmission control method of power line communication that can reduce the data collision caused by using.

1 is a block diagram showing the structure of a system using power line communication;

2 is a flowchart illustrating a data transmission control method of power line communication according to the present invention;

3 is a flowchart illustrating a data transmission control method of power line communication according to the present invention;

4A and 4B are flowcharts showing interrupts generated during power line communication

<Explanation of symbols on main parts of the drawings>

1: power line communication modem 2: home appliance

According to a feature of the data transmission control method of the power line communication according to the present invention for solving the above problems, a plurality of home appliances are connected to the shared power line to transmit and receive data and buffering (data) so that data can be transmitted between the home appliances An initialization step of supplying power to a power line communication modem performing a) and initializing a state variable and a timer by a microcomputer of the home appliance; A data transmission determination step of detecting data activity of another home appliance sharing the power line by the microcomputer initialized through the initialization step and determining whether data is being transmitted or received on the power line and whether there is data to be transmitted by the home appliance; ; Performing a data transmission step of monitoring whether a collision occurs with data of another home appliance connected to the power line while the home appliance is transmitting data through the power line, when it is determined that data transmission is possible in the data transmission detection step; The data retransmission step of stopping data transmission and retrying data transmission after a random time elapses when the data collision occurs during the data transmission step.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 illustrates a structure of a system using power line communication in general, and a home appliance 2 extracts only a communication signal from a power line through a dedicated connection device that is a kind of modem, that is, a power line communication modem (PLC modem: 1). Allows sending and receiving of data and buffering.

In the power line communication, when a signal is transmitted on the power line using chirp, a unique waveform exists in a header, which is the first part of the packet, and a tail, which is the last part of the packet, and in the present invention, the CSMA / CD is used by using the waveform. (carrier sense multiple access / collision detection)

CSMA / CD (carrier sense multiple access / collision detection) communication detects whether there is no data transmission from other terminals connected to the shared medium, and if no data activity is detected on the shared medium, all terminals can use the shared medium. . When it is confirmed that the shared medium is available, a terminal having data to be transmitted transmits its own data, and at this time, two or more terminals can transmit data, thereby monitoring a collision with another terminal during data transmission. If a collision with the other terminal is detected, transmission is stopped, and data transmission is started again from the beginning after a certain delay time after the transmission is stopped.

2 is a diagram illustrating a data transmission control method of power line communication according to the present invention, and the first step is connected to each home appliance 2 for power line communication to supply power to a power line communication modem 1 for transmitting and receiving data. When this is applied, the microcomputer of the home appliance 2 initializes the state variables S, B, and P and the timer, and the timer starts to drive (see S11).

The state variables S, B, and P include whether data is being transmitted and received on the power line, whether there is data to be transmitted (S and B), and the number of transmission attempts P to transmit data through the power line.

In this case, the timer is a minimum time required to recover to a state capable of transmitting / receiving the next frame after transmitting / receiving one frame, and a post-collision delay time caused by two or more nodes attempting to transmit the frame simultaneously. Count.

In the second step, by detecting data activity of other household appliances 2 sharing the power line, it is determined whether data is being transmitted or received on the power line and whether there is data to be transmitted (S, B). If the result of the determination is negative, the power line data transmission status and transmission data presence (S, B) are continuously detected (see S12).

If the determination result of the second step S12 is affirmative, in the third step, the power line determines that the home appliance 2 can use the power line for data transmission, and thus the transmission data that the home appliance 2 should transmit. Is buffered by the power line communication modem 1 and the transmission data is transmitted to the power line. (See S13.)

In the fourth step, it is determined whether the transmission data of the third step S13 collides with data transmitted by another home appliance 2 connected to the power line during transmission. In step 5, the transmission of the transmission data is stopped and the transmission attempt count P of the data, which is the state variable initialized in the first step, is increased by one (see S14 and S15).

If the determination result of the fourth step S14 is negative, in the sixth step, it is determined whether the transmission of the data started to be transmitted in the third step S13 is completed, and if the determination result of the sixth step is negative, Returning to step 3 (S13), the data transmission is continued (see S16).

If the determination result of the sixth step (S16) is affirmative, in the seventh step it is determined that all the data to be transmitted from the home appliance (2) is completed, the presence of the data to be transmitted and the number of transmission attempts (B). And the state variable indicating P) is initialized as in the first step (see S17).

The method of controlling data transmission of power line communication will be described in detail with reference to FIG. 3. The first process monitors whether data transmission and reception is performed from another home appliance 2 connected to a power line, and determines the monitoring result. A power line state variable (S) expressed in the form and a data state variable (B) for determining whether there is data to be transmitted by the home appliance (2), and a transmission attempt state variable for storing the number of attempts to transmit the data through the power line Initialize (P) to '0' (see S21).

At this time, a timer that counts the minimum time required to recover to the state where the next data can be transmitted / received after transmitting / receiving one data and the post-collision delay time caused by two or more nodes attempting data transmission at the same time. Also initialize to '0'.

In the second process, the driving of the timer initialized in the first process S21 is started to count a predetermined time at which data is not transmitted to the power line, and the third process is performed by the power line communication modem 1. Transmit and buffer the data to be transmitted over the power line (see S22 and S23).

The fourth process determines whether the buffering of the data transmitted to the power line communication modem 1 is completed in the third process. If the determination result of the fourth process is negative, the buffering of the data is not completed yet. The data continues to be transmitted until buffering is completed (see S24).

If it is determined that the data buffering is completed, in step 5, the data state variable B is set to '1' to inform the power line communication modem 1 that the data has been buffered and that there is data to be transmitted through the power line. In step 6, the power line state variable S is monitored to determine whether there is no data being transmitted by the other home appliance 2 so that the power line can transmit data (see S25 and S26).

If it is determined that there is data being transmitted in the sixth step S26, the process returns to the sixth step S26 to continuously monitor whether the state of the power line is capable of data transmission, and the determination result of the sixth step S26. If is affirmative, in the seventh step, data is transmitted through the power line after being delayed for a random time according to the data transmission attempt number P (see S27).

At this time, the maximum number of transmission attempts (Max P) of the data is limited, and the number of transmission attempts (P) of the data is inversely related. That is, as the number of times P of data transmission attempts increases, the waiting time for data transmission becomes shorter, so that data that fails to be transmitted may be preferentially transmitted.

In the eighth step, the unique waveform generated in the header and tail portion of the packet during power line communication is monitored in the header of the data transmitted in the seventh step S27, and in the ninth step, the header monitored in the eighth step By analyzing the waveform of the monitor, it is monitored whether or not the data transmitted through the power line has collided with the data transmitted from the other home appliance 2 (see S28 and S29).

If it is determined that a data collision has occurred in the ninth process S29, in the tenth process, the transmission attempt count P of the data is increased by '1' to transmit the data calculated in the tenth process in the eleventh process. It is determined whether the number P is greater than the set maximum transmission attempt frequency Max P (see S30 and S31).

If the determination result of the eleventh step (S31) is negative, the data of the home appliance (2) can be retransmitted, and thus waits for a predetermined time and attempts to transmit the data again, and the determination result of the eleventh step (S31) If it is affirmative, in the twelfth step S32, the data currently attempted to be transmitted by the home appliance 2 is determined to be a transmission error because it can no longer be transmitted. (See S32)

If a collision is not detected during the data transmission of the ninth process S29, it is determined that the data transmission is completed in the thirteenth process S33, and then the fourteenth process following the twelfth process and the thirteenth processes S32 and S33. (S34) prepares the next data transmission by initializing the state variables (P, B) and the transmission data buffer (see S33 and S34).

Referring to the flowcharts shown in FIGS. 4A and 4B, an interrupt generated during data transmission through the power line will be described. FIG. 4A is an interrupt generated internally during transmission, and FIG. 4B relates to a timer interrupt. .

In the first step, when data is transmitted and the state of the power line to which the home appliance 2 is connected is in a busy state, in the second step, it is determined whether a unique waveform is detected in the tail portion of the data transmitted through the power line. If the determination result of the second step is affirmative, the third step determines that the power line is in a data transmission state and converts the power line state variable S to '1' (see S41, S42, and S43).

However, if the determination result of the second step S42 is negative, in the fourth step, the power line determines that data transmission is impossible and initializes the power line state variable S to '0' and the timer initializes the counter. Start (see S44).

The interrupt of the timer detects whether the timer being countered is greater than or equal to the maximum waiting time of the data in the first step, and when the detection time of the first step becomes greater than the counting time, the second step transmits data to the power line. It is determined that it is possible to convert the power line state variable S to '1' and terminate the counter of the timer (see S51 and S52).

As described above, the method for controlling data transmission of power line communication according to the present invention continuously detects the state of the power line before performing data transmission through the power line in a power line communication system in which a plurality of products are connected to the same power line, By initiating the transmission, data collision can be reduced during data transmission.

The data transmission control method of the power line communication of the present invention configured as described above continuously detects the state of the power line before starting mutual data transmission through the power line in a power line communication system in which a plurality of home appliances are connected to the same power line. Therefore, the transmission is started only under ideal conditions, thereby reducing the data collision and increasing the transmission efficiency.

In addition, the data transmission control method of the power line communication according to the present invention is a logic that can be implemented in the microcomputer embedded in the home appliance or power line modem without adding a separate component, thereby reducing the additional cost. have.

Claims (6)

A plurality of home appliances are connected to a shared power line, and power is supplied to a power line communication modem that transmits and receives data and buffers data so that data can be transmitted between the home appliances, and the microcomputer of the home appliance sets a state variable and a timer. An initialization step of initializing; A data transmission determination step of detecting data activity of another home appliance sharing the power line by the microcomputer initialized through the initialization step and determining whether data is being transmitted or received on the power line and whether there is data to be transmitted by the home appliance; ; Performing a data transmission step of monitoring whether a collision occurs with data of another home appliance connected to the power line while the home appliance is transmitting data through the power line, when it is determined that data transmission is possible in the data transmission detection step; And a data retransmission step of stopping data transmission and retrying data transmission after a random time elapses when the data collision occurs during the data transmission step. The method of claim 1, And a data transmission completion step of initializing the state variable when the data is transmitted without collision through the data transmission step or the data retransmission step. The method of claim 1, And the state variable includes whether data is being transmitted and received on the power line, whether there is data to be transmitted, and the number of transmission attempts of data to be transmitted through the power line. The method of claim 1, And the timer counts the minimum time required to return to a state capable of receiving the next message after transmitting / receiving one data and counts a random time after two or more data collisions. The method according to claim 1 or 3, The data retransmission step may be limited to retransmission when the number of transmission attempts increased due to a data collision between the home appliance and another home appliance is smaller than the maximum transmission attempt number, which is a limit in which data that fails to be transmitted may be transmitted. A data transmission control method for power line communication. The method according to claim 1 or 3, And the random time in the data retransmission step is inversely proportional to each other as the number of transmission attempts of the data increases.