JPS61234638A - Method for synchronous communication - Google Patents

Abstract

PURPOSE:To eliminate the necessity of transmitting a synchronizing signal separately from data errors between transmission and reception, by adopting an encoding system which inverts the presence/absence of carriers 1 bit by 1 bit and performing synchronization whenever a carrier is detected. CONSTITUTION:High-frequency signals superposed upon commercial power supply of a commercial power line (a) are separated and detected by a high-frequency transformer 1 for superposing and separating signal and the separated high-frequency signal components are frequency-divided by means of a demodulator section 3 after they are amplified by a receiving amplifier section 2. Then the address section DA for its own station of a message signal is compared with an address set by an address setting section 6 by means of a transmission-reception controller 4 and, when the message signal is addressed to its own station, an equipment controlling section 5 is controlled in accordance with a command. When the signal which is frequency-divided by the demodulator section 3 is a carrier of a prescribed time width which inverts, bits '0', '1', 'STOP', and 'EOM' are discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a communication method for synchronizing transmission and reception during communication between a plurality of devices and terminal devices.

Conventional technology Conventionally, when communicating signals between multiple communication devices.

Although there are various communication methods, it is common to use a serial synchronous communication method if devices are to be separated by a certain distance and communication is to be performed while ensuring reliability.

This synchronous communication method includes the start-stop-domei method and the focus-synchronization method, each of which employs a synchronization method depending on the type of communication.

FIG. 7 shows an example of the signal waveform of the start-stop synchronization method, and FIG. 7B shows an example of the signal waveform of the bit synchronization method. STA is a start bit, and it detects this start bit and establishes synchronization. ' Next, after a certain period of time when the start bit is detected, b7. b6゜b5
．． b4. b6. b2. b4. The state of each bit is sampled in the order of bo, and a determination of 1 or 0 is made. Furthermore, the parity bit is sampled, and a stop bit called STO is received to complete the series of message reception. In this method, synchronization is established every time one byte of signal is transmitted, and it is necessary that the period of the sampling signals on the transmitting side and the receiving side be constant. B is the signal waveform of the bit synchronization method,
S is a bit synchronization signal. If the synchronization signal is at a constant position relative to the bit of the information signal, bit 3 /
, - If a sampling signal is created based on the synchronization signal, each bit can be sampled accurately.

The problem to be solved by the invention is that the start-stop synchronization method described in L is based on the start bit.
Since 1-bit synchronization is performed, the bit sending timing on the sending side and the receiving timing on the receiving side must match, and the timing on the sending and receiving sides may vary due to variations in the basic clocks on the sending and receiving sides. When a misalignment occurs,
Although the bit immediately after the start bit is detected accurately, a difference occurs between the transmitted signal and the received signal as they approach the stop bit, and the problem is that the adjacent bit is sampled based on this difference.

On the other hand, in the bit synchronization method, the synchronization signal is transmitted separately from the message frame, and the message frame is sampled based on the synchronization signal, so that bit errors due to shifts in transmission/reception timing as in the start-stop synchronization method described above do not occur. However, since the synchronization signal must be transmitted separately from the message frame, a separate line for transmitting the synchronization signal or a multiplexing means for multiplexing the synchronization signal with the signal is required, which increases costs. There is a drawback.

Means for Solving the Problems In order to solve the above-mentioned drawbacks, the present invention employs an encoding method that inverts the presence or absence of a carrier on a bit-by-bit basis.
Furthermore, the structure is such that synchronization is performed every time a transport carrier is detected.

Function: Since the synchronous communication method according to the present invention performs synchronization every time the carrier of the received signal is detected, unlike the frame synchronization method, it is possible to reduce the influence of clock errors between the transmitting device and the receiving device on transmission and reception. can.

Embodiment One embodiment of the present invention will be described below with reference to FIGS. 1 to 6. FIG. 1 is a block diagram of a communication transmission terminal using the communication method according to the present invention, and FIG. 2 is a signal waveform diagram of each part.

The carrier communication device includes a high frequency transformer 5 for signal superposition and separation.
.

S1. Reception amplifier section 2. Demodulator 3. Transmission/reception controller 4
1 equipment control unit 5. It is constituted by an address setting section 6. Here, signal reception will be explained. commercial power line a
When there is a signal in which a commercial power supply and a high frequency signal are superimposed, the commercial power component and the high frequency signal component are separated by a high frequency transformer 1 for signal superimposition and separation, the high frequency signal component is amplified by a reception amplification section 2, and a demodulation section 3. is input. The keynote section 3 divides the frequency of the high frequency signal and inputs it to the transmission/reception controller 4.

The transmitting/receiving controller 4 compares the address section DA of the message signal shown in FIG. 4 for the local station with the address set in the address setting section 6, and if the signal is for the local station address, the command section of FIG. The device control unit 5 is controlled according to the command specified by COM. FIG. 2 shows the waveforms of each part, and a, b, and c correspond to a, b, and c in FIG. 1, respectively. Note ' is an enlarged view of the part indicated by the circle in b.

The present invention uses an encoding method as shown in FIG.

Here, the signal is +1g, 50", ゞ5TOP"
.

There are four states, ``EOM'', and each signal is represented by times 1, 2, 3, and 4 times the minimum unit time T1, and there is always a presence or absence of a carrier signal between adjacent bits. Uses an inverted encoding method. In FIG. 3, the signal 1' is a 4-bit continuous signal, and by the encoding method of the present invention, the presence or absence of a carrier is inverted every T1 time as shown in the figure.

B is a series of bit data "O", and is a series of carriers expressed in 2XT4 time.C is 5 TOP bits, which are located at the boundaries of 8-bit data as shown in Figure 4, and are data in units of 8 bits. 3X
T1 is expressed in time.

Similarly, 9 represents the end (6 41''-like total 10', 1-'!, and is expressed in 4XT, time).

In Figure 4, S and A are the addresses of your own station, D9 are the addresses of the other station (the address part is from the other station to your own station), and B and C are the DA.
The byte length of the TA section, COM is a control command, DAT is control data, and S and C are message error detection codes.

The bit demodulation algorithm of the present invention will first be explained using FIGS. 6 and 6 for the case where there is a carrier. carrier signal a of arbitrary bit length
When input, the counter 7 of the demodulator 3 starts counting amplifier, and at the same time, the signal is input to the IRQ terminal of the transmitting/receiving controller 4. When the transmitting/receiving controller 4 receives an IRQ, it monitors the counter output for 14 hours, and if a count number above a certain value is detected during that time, it determines that it is not noise but a normal carrier signal, and transmits/receives after the IRQ occurs. The internal timer t of the controller 4 is run automatically and the value of the counter 7 is monitored after a time T1 has elapsed. If the counter value is within the set range, it is determined that the carrier is continuous for T1 time. After checking the counter value, immediately output the reset signal r. Counter 7 is set, but the carrier signal continues.

Start counting again. Next, after T1 time has elapsed, the counter value is counted again to measure the duration of the carrier, and T1
Bit 'o', bit '1' depending on how long the time carrier lasts.

5TOP, determine ROM. When there is no more carrier signal in the power supply, the IRQ receiver becomes available and waits for the next carrier input. Here, the timer that started running due to the above-mentioned IRQ generation is T.

Since the timer output is made with time as one cycle, by monitoring the counter value every T thereafter, it is possible to determine the number of carriers present in the power line within 77 hours. Furthermore, since the internal timer of the transmitting/receiving controller 4 is reset when the state changes from no carrier signal on the power line to a state where there is a clear carrier signal, the maximum time is 6T4. Since it can be reset with a minimum of 2T, synchronization can be achieved again in about half the time required by the asynchronous synchronization method described above at the worst.

Effects of the Invention The present invention has the advantage that, unlike the start-stop synchronization method, error accumulation caused by one-message frame synchronization using a start bit has little adverse effect on sampling per bit, and furthermore, unlike the bit synchronization method, the error accumulation caused by synchronization of one frame per frame with a start bit has little adverse effect on sampling per bit. There is no need to transmit a synchronization signal.

The carrier of the underground transport communication device was detected, and
This is because it is determined that it is a signal carrier only when a specified number of similar carriers are input within a certain period of time.

9., -F Noise of short duration, such as impulse noise.

A highly reliable synchronization method is obtained without being reset by low frequency noise.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a communication device adopting the synchronous communication method according to the present invention, FIG. 2 is a signal waveform diagram of each part of FIG. 1, and FIG. 3 is a carrier waveform diagram when bits "11'" are continuous. Figure 3B is a carrier waveform diagram when bits 50' are continuous;
Figure C is a signal waveform diagram of 5TOP bits, and the third figure is a ROM diagram.
Bit signal waveform diagram, Figure 4 is a message frame configuration diagram, Figure 6 is each signal waveform diagram of the demodulation section, Figure 6 is a concrete configuration diagram of the demodulation section, and Figures 7A and B are conventional diagrams. FIG. 3 is a signal waveform diagram of the method. 1...Transformer for signal superposition and separation, 2...
・Reception amplification section, 3... Demodulation section, 4...
Transmission/reception controller, 5... equipment control section, 6.
...Address setting section. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3 Figure 5 Figure 1

Claims (1)

[Claims] A carrier communication device that performs communication by superimposing high-frequency signals on a commercial power line. It uses an encoding method that defines bits by the time the carrier is superimposed and the time the carrier is stopped, and each time a carrier is detected. The method is characterized in that bit synchronization is performed, furthermore, signal detection for bit synchronization is performed for a certain period of time from a predetermined time of a defined bit, and synchronization is established only when a carrier can be detected for a certain period of time or more. Synchronous communication method.