JPH0738534A - Data transmitting method - Google Patents

Abstract

PURPOSE:To improve an error catching rate and to speedily detect error by checking complementariness between both data each time one piece of data and the complementary data are received. CONSTITUTION:The combination of the L level of 30mus and the H level of 90mus following it expresses '0' and the combination of the L level of 60mus and the H level of 60mus following it expresses '1'. One cycle is 120mus. In this case, when one piece of data and the complementary data are continuously transmitted, both the data are extremely adjacent in terms of time so that it can be quite rare to invert both the data and only one of them can be normally inverted when they are affected by disturbance. When either of the data or the complementary data are inverted by the disturbance, transmission error can be surely detected by checking the complementariness between both the data on the reception side since the complementariness between both the data is disordered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission method used in a data transmission system such as a multiple transmission system for wiring reduction in factories, plants, etc.
More specifically, it relates to improvement of a method of detecting a transmission error due to the influence of disturbance.

[0002]

2. Description of the Related Art A schematic example of a data transmission system is shown in FIG. This data transmission system sends data from the transmitter 2 to the receiver 4 via the transmission line 6. A multiplex transmission method is usually employed for data transmission.

In such a data transmission system,
As a method of detecting a transmission error due to the influence of disturbance such as noise, the following sum check method has been conventionally used.

That is, for example, as shown in FIG. 7, after a series of data, sum check data indicating the sum A of the series of data is added, and such data is transmitted from the transmitting side. Then, the receiving side compares the sum of the received series of data with the sum check data (A in this case),
If both match, it is determined to be normal, and if they are different, it is determined to be incorrect.

[0005]

However, the conventional data transmission method as described above has a problem that a transmission error may not be detected when a plurality of data are inverted due to the influence of disturbance. . For example, as shown in FIG. 8, when two data (data 0 and data n in this example) are inverted due to the influence of disturbance, the sum of the series of data received on the receiving side is the sum of the normal case. (Ie A), no such transmission error can be detected.

Such a problem is serious in a severe noise environment such as in a factory.

Further, in the conventional data transmission method as described above, even if a transmission error occurs during the transmission of a series of data, the transmission error is detected on the receiving side as the sum of the series of data and the sum check data. There is also a problem that the transmission error is detected slowly because it cannot be detected until the time of comparing.

Therefore, the main object of the present invention is to provide a data transmission method capable of improving the error capture rate and shortening the time until error detection.

[0009]

In order to achieve the above object, the data transmission method of the present invention, when transmitting one "0" or "1" data from the transmitting side, stores the data and its value. Continuously transmit the inverted complementary data,
Each time the receiving side receives the above-mentioned one data and the complementary data, the complementarity between the two data is checked.

[0010]

When one data and its complementary data are continuously transmitted as described above, since both data are extremely close in time, both data may be inverted when affected by disturbance. Are extremely rare, and usually only one or the other flips. If only one of them is inverted, the complementarity between both data is broken, so by checking the complementarity between both data on the receiving side, the transmission error can be surely detected. Therefore, the error capture rate when affected by disturbance is improved.

Further, in the above method, the complementarity between both data is checked every time one data and its complementary data are received. Therefore, the time until the error detection is greatly affected by the disturbance. Short and quick detection is possible.

[0012]

FIG. 1 is a diagram showing an example of a transmission signal waveform used in the data transmission method according to the present invention. In this figure, "I / O service" is a period for processing input and output, "Start sync signal" is a signal for synchronizing communication start, and "Data 0 to n" are the present invention. Is data expressed according to. T is a period for one data, which is, for example, 120 μs as described later.

In this embodiment, when one piece of data "0" or "1" is transmitted, the data and complementary data of which the value is inverted are paired and continuously transmitted. . Then, each time the receiving side receives one "0" or "1" data and complementary data following it, complementarity between the two data (that is, if one is "0", the other is "1"). I try to check that.

A more specific example of the data expression method in this embodiment is shown in FIGS.

FIG. 2 shows an example of signal waveforms when transmitting data “0”, and FIG. 3 shows an example of signal waveforms when transmitting data “1”. In this embodiment, whether the data is "0" or "1" is expressed by the length of the pulse width (that is, by pulse width modulation). That is, 3
A combination of an “L” level of 0 μs and a subsequent “H” level of 90 μs represents “0”, and a combination of an “L” level of 60 μs and a subsequent “H” level of 60 μs represents “1”. One cycle is 120 μs. The same applies to the expression of complementary data.

It is possible to use pulse amplitude modulation which utilizes the difference in amplitude, instead of pulse width modulation, in order to express "0" or "1" data, but pulse width modulation is more preferable. This is preferable because it is unlikely to be affected by disturbances such as fluctuations in power supply voltage and noise.

The check of complementarity on the receiving side can be easily performed by using a known logic means.

When one data and its complementary data are continuously transmitted as described above, both data are extremely close to each other in time, so that both data are inverted when affected by disturbance. Are extremely rare, and usually only one or the other flips.

That is, since one data and its complementary data are very close to each other in terms of time, when they are affected by a disturbance, both data are usually affected in the same way. For example, in the case of a disturbance that causes a part of the signal to go to the “L” level, such a disturbance is added to both data, and conversely, when the disturbance causes a part of the signal to go to the “H” level, both data Such disturbance is added to.

FIG. 4 shows an example of the case where a disturbance that brings part of the signal to the "L" level is applied. in this case,
Although it is possible that the data of "0" is inverted to "1", at the same time, the complementary data of "1" is not inverted to "0". This is because, in order to invert the complementary data of "1" to "0", a disturbance that causes a part of the signal to be at "H" level is applied to that part, contrary to the part of the immediately preceding data. It must be because that usually does not happen.

FIG. 5 shows an example of the case where a disturbance that causes a part of the signal to go to the "H" level is applied. in this case,
It is possible that the data of "1" is inverted to "0", but at the same time, the complementary data of "0" is not inverted to "1". This is because in order to invert the complementary data of "0" to "1", a disturbance that causes a part of the signal to be at "L" level is applied to that part, contrary to the part of the immediately preceding data. It must be because that usually does not happen.

As described above, when only one of the data and its complementary data is inverted due to the disturbance, the complementarity between the two data is broken, so that the receiving side checks the complementarity between the two data to transmit the data. It is possible to reliably detect an error. Therefore, the error capture rate when affected by disturbance is improved. As a result, this data transmission method is particularly effective in use in a severe noise environment such as a factory.

Further, in the above method, the complementarity between both data is checked every time one data and its complementary data are received. Therefore, the time until the error detection is greatly affected by the disturbance. Short and quick detection is possible.

In this embodiment, the pulse width modulation which is not easily affected by the disturbance is used as the method of expressing the data "0" or "1". However, even if the pulse amplitude modulation is used, only one pulse width modulation is used. Since the data and its complementary data are very close to each other in time, if they are affected by a disturbance, both data are usually affected in the same way. It is possible to reliably detect an error.

[0025]

As described above, according to the present invention, one data and its complementary data are continuously transmitted, and when either one of the two data is usually affected by a disturbance. Since only one of them is inverted and the complementarity is lost,
By checking the complementarity between both data on the receiving side, it is possible to reliably detect a transmission error. Therefore, the error capture rate when affected by disturbance is improved.

Further, according to the present invention, the complementarity between both data is checked every time one data and its complementary data are received. Therefore, the time until the error detection is greatly affected by the disturbance. Short and quick detection is possible.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a transmission signal waveform used in a data transmission method according to the present invention.

FIG. 2 is an enlarged view showing an example of a signal waveform when data “0” is transmitted.

FIG. 3 is an enlarged view showing an example of a signal waveform when data “1” is transmitted.

FIG. 4 is a diagram showing an example in which a disturbance is added to the signal waveform of FIG.

5 is a diagram showing an example in which a disturbance is added to the signal waveform of FIG.

FIG. 6 is a schematic diagram showing an example of a data transmission system.

FIG. 7 is a diagram showing an example of transmission data of a conventional sum check method.

FIG. 8 is a diagram showing an example in which a disturbance is added to the transmission data of FIG.

[Explanation of symbols]

 2 transmitter 4 receiver 6 transmission path

Claims (1)

[Claims] 1. In a data transmission system, when one "0" or "1" data is transmitted from a transmitting side, the data and complementary data whose value is inverted are continuously transmitted, and a receiving side. 2. The data transmission method according to claim 1, wherein the complementarity between both data is checked every time the one data and the complementary data subsequent thereto are received.