JPH11284551A - One-way communication method from plural transmitters to single receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize one-way communication of plural transmitters and also surely perform it. SOLUTION: In this one-way communication method, which uses an AC power line as a communication line and transmits a signal from plural transmitters to a single receiver in a one-way direction, the plural respective transmitters normally transmit a signal to the receiver periodically by a timer that is synchronized with the voltage of the AC power line, switch the timer to an operation by an internal oscillation circuit at the service interrupt of the AC power line and also to transmit the state of the timer, adding to the signal at the transmitting of the signal (#1 to #6).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a unidirectional transmission of signals from a plurality of transmitters to a single receiver using an AC power line such as a distribution line for supplying AC power as a communication path. The present invention relates to improvement of a communication method.

[0002]

Conventional one-way communication of this kind, as shown in FIG. 4, has been carried out the transmission time T _B for each random transmission time T _A, or fixed time alone or in combination.

[0003]

In the conventional one-way communication as shown in FIG. 4, the transmission times of a plurality of transmitters may coincide with each other in the case of random transmission. If the accuracy of the timer that measures the fixed time is low when transmission occurs at regular intervals, the transmission time interval between the transmitters must be set long, and a large number of It was difficult to install a transmitter. If the accuracy of the timer deteriorates,
In addition to the problem of only a faulty transmitter, a problem of the entire system may occur, and a fault of one transmitter may lead to a stop of system functions. (Object of the Invention) An object of the present invention is to stabilize one-way communication of a plurality of transmitters, and
It is an object of the present invention to provide a reliable one-way communication method from a plurality of transmitters to a single receiver.

[0004]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a unidirectional transmission of signals from a plurality of transmitters to a single receiver using an AC power line as a communication path. In the communication method, each of the plurality of transmitters normally transmits a signal to the receiver periodically by a timer synchronized with the AC power of the AC power line, and the timer is controlled by an internal oscillation circuit when the AC power line fails. And transmitting the signal by adding the state of the timer to the signal when transmitting the signal.

[0005]

FIG. 1 is a diagram showing an example of a system according to an embodiment of the present invention. Multiple transmitters 1
.., 1n are connected to an AC power line 2 such as an AC distribution line used as a communication path, and perform one-way communication with a single receiver 3 also connected to the AC power line 2.
Such a system is assumed to be, for example, an automatic meter reading system including a terminal device installed in each consumer as a transmitter and a power company repeater as a receiver.

FIG. 2 is a block diagram showing an outline of an example of the transmitters 1a, 1b... 1n. 4 is a power line connection terminal, 5
Is a data input terminal for inputting data to be transmitted from an external device. When data is input from the data input terminal 5, the arithmetic circuit 6 temporarily stores the data in the memory 6a,
When the timer current time of the timer 7 coincides with the transmission time, the data is converted by the transmission circuit 8 into a power line carrier signal,
It is injected into the AC power line 2 and transmitted to the receiver 3. The power supply synchronizing pulse circuit 9 generates a power supply synchronizing pulse synchronized with the power supply voltage of the AC power line 2, and is normally supplied to the timer 7 by the arithmetic circuit 6 via the switching circuit 10 closed on the power supply synchronizing pulse circuit 8 side. . The timer 7 is driven by the power supply synchronization pulse, measures the current time of the timer, and inputs the current time of the timer to the arithmetic circuit 6. The power failure detection circuit 8 detects a power failure of the AC power line 2 and transmits the detection result to the arithmetic circuit 6. When a power failure is detected, the arithmetic circuit 6 switches the switching circuit 10 to the oscillation circuit 12 side. The oscillating circuit 12 is an internal oscillating circuit based on crystal oscillation or the like, and is operated by a power supply for power failure such as a battery or a capacitor during a power failure to output an oscillation pulse.

The operation of the transmitter shown in FIG. 2 will be described with reference to the flowchart of FIG. In step 1, the arithmetic circuit 6 determines whether or not a power failure has occurred based on the detection result of the power failure detection circuit 11, and when no power failure has occurred, switches the switching circuit 10 to the power synchronization pulse circuit 9 side,
To be supplied. As a result, the timer 7 is driven by the power supply synchronizing pulse, and measures the current time of the timer. In the case of a power failure, the arithmetic circuit 6 switches the switching circuit 10 to the oscillation circuit 12 in step 3 and drives the timer 7 with the oscillation pulse from the oscillation circuit 12. When it is determined in step 4 that the transmission time has been set differently for each transmitter in advance, in step 5, the arithmetic circuit 6 stores in the memory 6
The transmission circuit 8 reads out the data stored in “a”, converts this data into a power line carrier signal, injects it into the AC power line 2, and transmits it to the receiver 3. When sending, step 6
, The timer current time of the timer 7, that is, the timer data is added to the data of step 5 and transmitted. At the time of a power failure, no data or timer data is sent.

.. 1n, the transmission time is determined by the timer 7 which is synchronized with the power supply voltage of the AC power line 2 in normal times when no power failure occurs.
No relative timer error occurs between the transmitters, and transmission is performed at a predetermined time interval between the transmitters. Therefore, even if a large number of transmitters are installed, one-way communication can be performed without causing signal collision. Also, at the time of a power failure, the timer 7 is driven by the built-in oscillation circuit 12, so that it is not necessary to reset the timer 7. further,
At the time of data transmission, the state of the timer 7, that is, the current time of the timer is added and transmitted, so that a transmitter having a large timer error can be found in the receiver 3 in advance, and stable system operation is possible. Becomes

[0009]

As described above, according to the present invention,
Since a plurality of transmitters normally perform a transmission operation using a timer synchronized with the voltage of the AC power line, a relative timer error between the transmitters does not occur, and signal collision can be eliminated. Further, even at the time of a power failure, the timer is driven by the internal oscillation circuit, so that it is not necessary to set the timer again. Furthermore, since the transmission is performed by adding the state of the timer at the time of transmission, a transmitter having a large timer error can be found in the receiver in advance, and stable system operation can be performed. Therefore, one-way communication of a plurality of transmitters can be performed stably and reliably.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an outline of an example of the transmitter of FIG. 1;

FIG. 3 is a flowchart illustrating an operation of the transmitter of FIG. 2;

FIG. 4 is a diagram showing conventional one-way communication.

[Explanation of symbols]

 1a, 1b... 1n Transmitter 2 AC power line 3 Receiver 4 Power line connection terminal 5 Data input terminal 6 Operation circuit 6a Memory 7 Timer 8 Transmission circuit 9 Power supply synchronization pulse circuit 10 Switching circuit 11 Power failure detection circuit 12 Oscillation circuit

Claims (1)

[Claims] 1. A one-way communication method using an AC power line as a communication path and transmitting a signal in one direction from a plurality of transmitters to a single receiver, wherein each of the plurality of transmitters generally includes A signal is periodically transmitted to the receiver by a timer synchronized with the voltage of the AC power line.When the AC power line fails, the timer is switched to an operation by an internal oscillation circuit, and when the signal is transmitted, the timer is used. A method for transmitting a unidirectional communication from a plurality of transmitters to a single receiver, wherein the state is added to the signal and transmitted.