JPH11154941A - Communication equipment, communication system and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication equipment, a communication system and a communication method where the data transmission efficiency and transmission accuracy are high. SOLUTION: A transmission unit includes an input circuit, a coding circuit 12 and a transmission circuit. A reception unit includes a reception circuit, a decoding circuit and an output circuit. The coding circuit 12 of the transmission unit has a start bit waveform generating circuit 121, a data coding circuit 122 and a signal changeover circuit 123. The start bit waveform generating circuit 121 outputs a start bit SB consisting of two pulses whose pulse width is wider than the length of 1 bit of data. The data coding circuit 122 encodes a parallel signal fed from the input circuit and outputs serial data DB. The signal changeover circuit 123 selects either the start bit SB fed from the start bit waveform generating circuit 121 or the data DB fed from the data coding circuit 122 and outputs the selected data as a transmission signal TR.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a communication device, a communication system, and a communication method for performing asynchronous data transmission.

[0002]

2. Description of the Related Art In asynchronous data transmission, when data is out of synchronization between a transmitting side and a receiving side, data is garbled. Therefore, accurate synchronization is important for securing communication reliability. As a method of synchronizing data, there are a start bit method, a synchronization character method, and the like.

In the start bit method, as shown in FIG. 10, a start bit is added to the head of data on the transmission side,
Data is transmitted following the start bit. The start bit has a pulse width longer than the length of each bit of data. On the receiving side, when the state of “1” continues in the received signal to some extent, the state is determined as a start bit, and data is synchronized at the falling of the signal.

On the other hand, in the synchronous character method, as shown in FIG. 11, a transmitting side adds a synchronizing character having the same length as the data to the head of a data group composed of a plurality of data, and a plurality of data following the synchronizing character. Send On the receiving side, upon detecting a synchronization character included in the received signal, the signal following the synchronization character is determined to be data.

[0005]

In asynchronous data transmission of the start bit system, as the communication distance increases, the waveform of a signal on the communication line becomes blunt due to the frequency characteristics of the communication line. In such a case, as shown in FIG. 12, the position of the falling edge of the start bit in the received signal changes with respect to the position of the falling edge of the start bit in the transmitted signal, and the sampling timing may be shifted. As a result, data is garbled and the data transmission accuracy is degraded.

On the other hand, in the asynchronous data transmission of the synchronous character system, a synchronous character having the same length as the data is added.
As shown in (1), the communication time is longer than in the start bit method, and the data transmission efficiency is lower.

An object of the present invention is to provide a communication device, a communication system and a communication method having high data transmission efficiency and high transmission accuracy.

[0008]

Means for Solving the Problems and Effects of the Invention (1)
A communication apparatus according to a first aspect of the present invention includes: a generation unit configured to generate a start bit having a frequency higher than data to be transmitted; an addition unit configured to add the start bit generated by the generation unit to the data; Transmitting means for transmitting a signal containing data to which a start bit has been added by the adding means.

In the communication device according to the present invention, a start bit having a higher frequency than data to be transmitted is generated, and the start bit is added to the data.
Then, a signal including data to which the start bit is added is transmitted.

[0010] Since the frequency of the start bit included in the signal to be transmitted is higher than the frequency of the data, when the waveform of the signal is distorted, the amplitude of the start bit included in the signal received on the receiving side is reduced. It becomes smaller than the amplitude. As a result, when it becomes impossible for the receiving side to detect the start bit, it becomes impossible to detect data.

In this case, data cannot be received, but incorrect data with garbled data will not be received. Therefore, dangerous operation such as malfunction of the device due to data corruption can be avoided. Also, since the frequency of the start bit is higher than the frequency of the data, the data transmission efficiency increases.

(2) Second invention A communication device according to a second invention is a receiving means for receiving a signal including data, and detects a start bit having a higher frequency than the data from the signal received by the receiving means. Detecting means for determining the data included in the signal received by the receiving means based on the start bit detected by the detecting means.

In the communication device according to the present invention, a signal including data is received, and a start bit having a higher frequency than the data is detected from the received signal. Then, data included in the received signal is determined based on the detected start bit.

Since the frequency of the start bit included in the transmitted signal is higher than the frequency of the data, when the waveform of the signal is distorted, the amplitude of the start bit included in the received signal is smaller than the amplitude of the data. Smaller. Thus, if it becomes impossible to detect the start bit included in the received signal, it becomes impossible to detect data.

In this case, data cannot be received, but incorrect data with corrupted data will not be received. Therefore, dangerous operation such as malfunction of the device due to data corruption can be avoided. Also, since the frequency of the start bit is higher than the frequency of the data, the data transmission efficiency increases.

(3) Third invention The communication device according to the third invention is the communication device according to the first or second invention, wherein the data comprises a serial signal including a plurality of bits having a fixed time width. , The start bit is composed of one or a plurality of pulses having a time width shorter than the time width of each bit of the serial signal.

In this case, since the pulse of the start bit has a pulse width shorter than the length of one bit of data,
Start bit can be identified, and
The transmission time of the signal including the start bit and the data is shortened.

(4) Fourth Invention A communication system according to a fourth invention adds a start bit having a higher frequency than data to be transmitted to data, and transmits a signal including the data to which the start bit is added. And a receiving unit that receives a signal transmitted from the transmitting unit and determines data included in the signal based on a start bit included in the received signal.

In the communication system according to the present invention, a start bit having a higher frequency than the data to be transmitted by the transmission unit is added to the data, and a signal including the data with the start bit added is transmitted. On the other hand, the signal transmitted from the transmitting unit is received by the receiving unit, and data included in the signal is determined based on a start bit included in the received signal.

In the communication system according to the present invention, the frequency of the start bit included in the signal transmitted by the transmission unit is higher than the frequency of the data. The amplitude of the included start bit is smaller than the amplitude of the data. Thereby, if it becomes impossible to detect the start bit included in the signal received by the receiving unit, it becomes impossible to detect data.

In this case, data cannot be received, but incorrect data with garbled data will not be received. Therefore, dangerous operation such as malfunction of the device due to data corruption can be avoided. Also, since the frequency of the start bit is higher than the frequency of the data, the data transmission efficiency increases.

(5) Fifth Invention In a communication method according to a fifth invention, a start bit having a higher frequency than data to be transmitted is generated at the time of data transmission, and the start bit is added to the data. A signal including data to which bits are added is transmitted, a start bit included in the received signal is detected when data is received, and data included in the received signal is determined based on the detected start bit. .

In the communication method according to the present invention, the frequency of the start bit included in the signal to be transmitted is higher than the frequency of the data. The bit amplitude is smaller than the data amplitude. As a result, when it becomes impossible to detect the start bit included in the received signal, it becomes impossible to detect data.

In this case, data cannot be received, but incorrect data with garbled data will not be received. Therefore, dangerous operation such as malfunction of the device due to data corruption can be avoided. Also, since the frequency of the start bit is higher than the frequency of the data, the data transmission efficiency increases.

[0025]

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

The communication system shown in FIG.
A, 100B and the communication line 3. The communication device 100A includes the transmission unit 1, and the communication device 100B
Includes a receiving unit 2. The transmitting unit 1 and the receiving unit 2 are connected via a communication line 3.

The transmission unit 1 includes an input circuit 11, an encoding circuit 12, and a transmission circuit 13. For example, one or more input devices are connected to the input circuit 11. Also,
The transmission circuit 13 is connected to the communication line 3.

The input circuit 11 supplies a signal input from the input device to the encoding circuit 12 as a parallel signal.
The encoding circuit 12 encodes (modulates) the parallel signal from the input circuit 11 and supplies the signal to the transmission circuit 13 as a serial signal. The transmitting circuit 13 transmits the serial signal from the encoding circuit 12 to the receiving unit 2 via the communication line 3.

The receiving unit 2 includes a receiving circuit 21, a decoding circuit 22, and an output circuit 23. The receiving circuit 21 is connected to the communication line 3. Also, for example, 1
Alternatively, a plurality of output devices are connected.

The receiving circuit 21 receives the serial signal transmitted from the transmitting unit 1 via the communication line 3 and supplies the serial signal to the decoding circuit 22. The decoding circuit 22 encodes (demodulates) the serial signal from the receiving circuit 21 and supplies it to the output circuit 23 as a parallel signal. The output circuit 23 outputs the parallel signal from the decoding circuit 22 to an output device.

FIG. 2 is a block diagram showing a configuration of the encoding circuit 12 of the transmission unit 1 of FIG. FIG. 3 is FIG.
5 is a timing chart for explaining the operation of the encoding circuit 12 of FIG. In this embodiment, the high level of each signal is
1 and the low level is "0".

As shown in FIG. 2, the encoding circuit 12 includes a start bit waveform generation circuit 121, a data encoding circuit 1
22 and a signal switching circuit 123.

Start bit waveform generation circuit 121 outputs start bit SB in response to transmission start signal ST, and outputs output request signal RQ and switching signal SW.
Is output.

The data encoding circuit 122 outputs the output request signal RQ output from the start bit waveform generation circuit 121.
, The parallel signal from the input circuit 11 of FIG. 1 is encoded, and a data DB composed of a serial signal is output.

The signal switching circuit 123 responds to the switching signal SW output from the start bit waveform generation circuit 121 to output the start bit SB output from the start bit waveform generation circuit 121 and the data encoding circuit 122. Data DB is selectively output as transmission signal TR.

As shown in FIG. 3, the transmission start signal ST
, A start bit SB consisting of two pulses is generated. The pulse width of each pulse of the start bit SB and the interval between the pulses are WS. The pulse width WS of each pulse of the start bit SB is the data DB
Is set shorter than the one-bit length WD. That is, the frequency of the start bit SB is set higher than the frequency of the data DB.

After the generation of the start bit SB, an output request signal RQ composed of a pulse is generated. The switching signal SW rises from “0” to “1” simultaneously with the output request signal RQ. When the switching signal SW is "0", the start bit S
B is output as the transmission signal TR, and when the switching signal SW is "1", the data DB is output as the transmission signal TR. Thereby, data DB is transmitted following transmission start bit SB in transmission signal TR.

FIG. 4 shows the receiving circuit 2 of the receiving unit 2 of FIG.
FIG. 2 is a block diagram illustrating a start bit detection circuit included in the example 1. FIG. 5 is a timing chart for explaining the operation of the start bit detection circuit of FIG.

As shown in FIG. 4, start bit detection circuit 211 outputs a detection signal DE in response to reception signal RC and clock signal CK. The decoding circuit 22
Data included in the received signal RC is determined based on the detection signal DE output from the start bit detection circuit 211, the data is decoded, and the decoded data is provided to the output circuit 23 of FIG. 1 as a parallel signal.

As shown in FIG. 5, received signal RC includes start bit SB and data DB. Start bit SB includes two pulses. The pulse width WS of each pulse of the start bit SB corresponds to two cycles of the clock signal CK, and the interval WS between the pulses also corresponds to two cycles of the clock signal CK. On the other hand, 1-bit length WD of data DB
Corresponds to 2.5 cycles of the clock signal CK. After the start bit SB is detected in the reception signal RC,
A detection signal DE composed of a pulse is generated.

FIG. 6 shows the start bit detection circuit 21 of FIG.
1 is a block diagram showing a configuration of FIG. As shown in FIG.
The start bit detection circuit 211
2 and an AND circuit 213.

Data signal D of shift register 212 is supplied with received signal RC, and clock signal CLK is supplied with clock signal CK. Receive signal RC applied to data terminal D of shift register 212 is clock signal C
The signal is shifted in response to LK and output from output terminals Q1 to Q8.

Output terminals Q3, Q of shift register 212
4, output signals from Q7, Q8 and output terminals Q1, Q
Inverted signals of the output signals from Q2, Q5, and Q6 are respectively supplied to a plurality of input terminals of the AND circuit 213, and the detection signal DE is output from the output terminal of the AND circuit 213.

Thus, when the received signal RC includes the start bit SB shown in FIG. 5, the detection signal DE rises for one cycle of the clock signal CK.

In this embodiment, the start bit waveform generation circuit 121 corresponds to a generation unit, the signal switching circuit 123 corresponds to an addition unit, and the transmission circuit 13 corresponds to a transmission unit.
Further, the receiving circuit 21 corresponds to the receiving means, the start bit detecting circuit 211 corresponds to the detecting means, and the decoding circuit 22
Corresponds to the determination means.

In the communication system of the present embodiment, FIG.
As shown in the figure, the pulse width WS of the start bit SB included in the transmission signal TR is equal to the one-bit length WD of the data DB.
Therefore, when the signal waveform is distorted on the communication line 3, the amplitude of the start bit SB included in the received signal RC becomes smaller than the amplitude of the data DB. Thereby, when it becomes impossible for the receiving unit 2 to detect the start bit SB included in the received signal RC,
It becomes impossible to detect the data DB. In this case, the reception of the data DB becomes impossible, but the reception of inaccurate data with the garbled data is also eliminated. Therefore, dangerous operation such as malfunction of the device due to data corruption can be avoided.

The length of the start bit SB is shorter than the length of the data DB, and the pulse width WS of each pulse of the start bit SB is one bit length WD of the data DB.
, The data transmission efficiency increases.

The start bit SB in this embodiment is 2
Noise from the start bit SB
Is prevented from being mistaken.

FIG. 8 is a waveform diagram showing another example of the start bit. In the example of FIG. 8, the start bit SB consists of one pulse. Start bit SB pulse width WS
Is set shorter than the length WD of one bit of the data DB. In this example, the length of the start bit SB is reduced.

FIG. 9 is a waveform diagram showing still another example of the start bit. In the example of FIG. 9, the start bit SB is composed of three pulses. The pulse width WS of each pulse of the start bit SB is set shorter than the length WD of one bit of the data DB, the interval between the first pulse and the second pulse is set to WS, and the second pulse is set to WS. The interval between the pulse and the third pulse is set to WS '. Here, WS ′> WS. In this example, it is prevented that the noise of a certain frequency is erroneously recognized as the start bit SB.

In the above embodiment, the communication device 100A
Includes the transmission unit 1 and the communication device 100B includes the reception unit 2, but the communication device 100A includes both the transmission unit 1 and the reception unit 2, and the communication device 100B may include both the transmission unit 1 and the reception unit 2. Good.

In the above embodiment, the transmitting unit 1 and the receiving unit 2 communicate with each other via the communication line 3, but the transmitting unit 1 and the receiving unit 2 communicate with each other by wireless communication. Alternatively, the transmission unit 1 and the reception unit 2 may be configured to perform optical communication.

When a control panel having a switch as an input device is connected to the transmission unit 1 of the above embodiment and output devices such as a lamp, a motor, a cylinder, and a valve are connected to the reception unit 2, a remote control device is used. Alternatively, a centralized control device is configured.

The present invention can be applied not only to a remote control device or a central control device but also to other communication systems for performing various data transmissions.

[Brief description of the drawings]

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

FIG. 2 is a block diagram illustrating a configuration of an encoding circuit of the transmission unit in FIG. 1;

FIG. 3 is a timing chart for explaining the operation of the encoding circuit of FIG. 2;

FIG. 4 is a block diagram illustrating a start bit detection circuit included in the reception circuit of the reception unit in FIG. 1;

FIG. 5 is a timing chart for explaining an operation of the start bit detection circuit of FIG. 4;

FIG. 6 is a block diagram illustrating a configuration of a start bit detection circuit of FIG. 4;

FIG. 7 is a waveform chart showing an example of a transmission signal and a reception signal in the communication system of FIG.

FIG. 8 is a waveform chart showing another example of a start bit.

FIG. 9 is a waveform chart showing still another example of a start bit.

FIG. 10 is a diagram showing a conventional start bit system.

FIG. 11 is a diagram showing a conventional synchronous character system.

FIG. 12 is a waveform diagram of a transmission signal and a reception signal in a conventional start bit system.

FIG. 13 is a diagram showing a comparison between a conventional start bit system and a synchronous character system.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 transmission unit 2 reception unit 11 input circuit 12 encoding circuit 13 transmission circuit 21 reception circuit 22 decoding circuit 23 output circuit 3 communication line 121 start bit waveform generation circuit 122 data encoding circuit 123 signal switching circuit 211 start bit detection circuit 212 Shift register 213 AND circuit 100A, 100B Communication device

Claims (5)

[Claims] A generating unit that generates a start bit having a frequency higher than that of data to be transmitted; an adding unit that adds the start bit generated by the generating unit to the data; And a transmission unit for transmitting a signal including data to which is added. 2. A receiving means for receiving a signal including data, a detecting means for detecting a start bit having a higher frequency than the data from a signal received by the receiving means, and a start detected by the detecting means. A communication device comprising: a determination unit configured to determine data included in a signal received by the reception unit based on a bit. 3. The data comprises a serial signal including a plurality of bits having a fixed time width, and the start bit comprises one or more pulses having a time width shorter than the time width of each bit of the serial signal. The communication device according to claim 1 or 2, wherein 4. A transmission unit for adding a start bit having a higher frequency than data to be transmitted to the data, and transmitting a signal including the data with the start bit added, and a signal transmitted from the transmission unit. And a receiving unit for receiving data and determining data included in the signal based on the start bit included in the received signal. 5. When transmitting data, a start bit having a higher frequency than data to be transmitted is generated, the start bit is added to the data, and a signal including the data to which the start bit is added is transmitted. A communication method, comprising: upon receiving data, detecting the start bit included in a received signal, and determining data included in the received signal based on the detected start bit.