JPS62271537A - Data collection system - Google Patents

Abstract

PURPOSE:To surely attain the identification of data even if the number of data collection terminal equipments is increased by connecting a sub data collection terminal equipment to the data collection terminal equipment connected to a signal line. CONSTITUTION:The titled system is provided with the data collection equipment comprising a Fourier analyzer 2 and a CPU 1, a signal line 4 and a data collection terminal equipment group 3. The terminal equipment group 3 consists of terminal equipments 31-34 connected to the line 4 and sub terminal equipments 311-343 connected to the equipments 31-34. Individual frequencies, e.g., f10-f13 are assigned to the sub terminal equipments 311-343 the same as the terminal equipments 31-34 to identify the address. Thus, the probability of superimposition of signals on the line 4 is decreased and the reduction in the amplitude is reduced. Thus, even if the number of the data collection equipments is increased, the data is identified surely.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Summary] In a configuration in which a plurality of data collection terminal devices are connected, logic is transmitted from the plurality of data collection terminal devices at different frequencies for each data collection terminal device. When data representing the level is superimposed and sent to the data collection device, the signal line is The number of data collection terminal devices that are directly connected to the device is within a certain value, multiple sub data collection terminal devices are connected to one data collection terminal device, and the data from the sub data collection terminal device is transmitted at the corresponding frequency. Send from data collection terminal device.

[Industrial application field]

The present invention relates to a data collection method, and more specifically, it receives data transmitted at different frequencies from a plurality of remotely located data collection terminal devices, analyzes the frequency, and transmits the data. The present invention relates to a data collection method that identifies a data collection terminal device and detects transmitted data.

[Conventional technology]

For example, on/off signals such as the open/close status of valves in plant equipment and the operation or stop status of equipment are transmitted from multiple data collection terminal devices located remotely at different frequencies for each data collection device, and central data collection is performed. Data collection systems are known in which a collection device receives transmitted data. These multiple data collection terminal devices and data collection devices are connected by coaxial cables, etc., and each has a logic level on/off signal at a different frequency so that the data collection terminal device can be identified.
I am trying to send off data. Also, between these multiple data collection terminal devices and data collection devices,
This is done asynchronously to simplify communication processing.

FIG. 5 shows a configuration diagram of a conventional data collection method.

A parallel Fourier analysis device 2 in which a plurality of data collection terminal devices 31 to 37 are connected via a signal line 4.
and sends the data to a data collection device comprised of cpu t. The data collection terminal devices 31-37 transmit data at different corresponding frequencies 11-fsa, respectively. The data collection terminal devices F31 to F37 asynchronously transmit data to the Fourier analysis device 2. As shown in FIG. 6, when the data collection terminal device 31 sends data to the Fourier analysis device 2 at the frequency f1, the Fourier analysis device 2
performs Fourier analysis on the received data and calculates the spectrum as shown in FIG. CI'll] identifies from this spectrum that the frequency is 11, so it is the data sent from the data collection terminal device 31 and the data is logical "1". That is, the frequency corresponds to the address of the data collection terminal device. For this reason, frequency analysis is performed using Fourier analysis as described above.

[Problem that the invention seeks to solve]

Since the data collection terminal device transmits data asynchronously, as shown in FIG.
, f2 are superimposed and the data is sent to the Fourier analysis bag N2. In this case, the data collection terminal device 31,
Even if a signal with different frequencies fl and f2 but the same amplitude A is sent from 32, the amplitude A° of the sum of the two signals wired ORed on the signal line 4 will be smaller than the original amplitude A.

Therefore, when Fourier analysis is performed on the superimposed received signal, peaks occur at rt and r2, respectively, as shown in FIG. 9, but their magnitudes are smaller than those in FIG. 7. If this value is larger than a certain threshold Lth, the identity of the data collection terminal device that sent the data and the content of the data can be identified.

However, when the number of data collection terminal devices that transmit data simultaneously is large, and the data often overlap with each other stochastically, as shown in FIG.
The signals p'2, pf3, and zf4 are superimposed and a signal whose amplitude is relatively reduced is received by a Fourier decomposition device. When this received signal is subjected to Fourier analysis, it becomes as shown in FIG. In other words, even though peaks occur at each frequency, they do not exceed the threshold, so C
A problem arises in that I'll 1 does not recognize that valid data has been received.

A conceivable method for solving the above problem is to provide an operational amplifier at each node to which each data collection terminal device of the signal line 4 is connected to compensate for the drop in signal level.

However, this method has the problem of reduced reliability due to the installation of the operational amplifier, in that if a failure occurs in the operational amplifier, data cannot be received from all data collection terminal devices connected to the signal line 4.

Another method is to change the aforementioned threshold according to the number of superimposed signals, but the reception frequency must first be detected as a prerequisite for changing the threshold level. There is a problem in that it is difficult to perform detection accurately.

[Means for solving problems]

In order to solve the above-mentioned problems associated with an increase in the number of data collection terminal devices, the present invention provides a plurality of data collection terminal devices that transmit data indicating logic levels using a plurality of signals of different and corresponding frequencies, and a plurality of data collection A signal line that connects the terminal device, and a data collection terminal device that is connected to the data collection terminal device via the signal line, receives data from the data collection terminal device, analyzes the frequency of the received data, and sends it out. and a data collection device that identifies a logic level and detects a logic level, wherein at least one of the plurality of data collection terminal devices transmits data indicating the logic level with signals of different and corresponding frequencies. The present invention provides a data collection system, characterized in that the data collection system is connected to a sub-data collection terminal device of 1, and data of signals of these corresponding frequencies are sequentially sent to the signal line within a predetermined time.

〔Example〕

FIG. 1 shows a configuration diagram of a data collection system according to an embodiment of the present invention.

The data collection method is Fourier analyzer 2 and CPU
1, a signal line 4 and a data collection terminal group 3. The data acquisition device and signal line 4 are conventional. The data collection terminal device group 3 includes a plurality of data collection terminal devices 31 to 34 directly connected to the signal line 4, and a sub data collection terminal device 31 connected to each data collection terminal device.
1~313°321~323. ..., 341-343
It consists of

The sub data collection terminal device also has a data collection function.
It is similar to the data collection terminal device. However, it is not directly connected to the signal line 4, but is once connected to a corresponding data collection terminal device, specifically, a data collection terminal device located nearby,
The configuration is such that data is sent to the Fourier analysis device 2 of the data collection device via the corresponding data collection terminal device. The sub data collection terminal device, like the data collection terminal device, uses individual frequencies, e.g. fiO, fli, f1.
2, f13 is assigned to identify the address.

In the embodiment of FIG. 1, each data collection terminal has three
1 sub-data collection terminal device is connected. Therefore, if the number of all terminal devices is the same, the number of data acquisition devices directly connected to the signal line 4 will be A compared to FIG. Therefore, the number of signals superimposed on the signal line 4 is probabilistically A, and the decrease in amplitude due to superposition is also reduced to A. In other words, superposition does not occur as in the conventional case, and therefore the decrease in amplitude It's also small.

The data collection terminal device 31 is a sub data collection terminal device 3
In addition to collecting data from 11 to 313, it also collects data regarding itself. After data collection, data collection terminal device 31. As shown in FIG.
Data is sent sequentially from fli to f13. It is assumed that the periods T1 to T4 for transmitting each data have the same value. The same applies to other data collection terminal devices and corresponding sub-data collection terminal devices.

When configured as described above and transmitting data via the signal line 4 as described above, the number of data superimpositions on the signal line 4 is A. Therefore, under the same conditions as in the case of FIG. 5, the number of signals superimposed as shown in FIG. 3 is A, and the decrease in amplitude is also small. Therefore, the Fourier analyzer 2
The spectrum calculated in Fig. 4 is as shown in Fig. 4.
It never becomes smaller than the threshold Lth.

As is clear from the embodiments described above, the number of data acquisition devices connected to the signal line 4 is limited to a range within which the amplitude reduction due to signal superimposition can be tolerated by the system. For data collection devices exceeding a predetermined number, data transmission is performed via a data collection terminal device directly connected to the signal line 4 without being directly connected to the signal line 4 as a sub data collection device.

As a result, even if the number of terminal devices from which data should be collected increases, data transmission from the data collection devices that are matched by frequency becomes possible.

In FIG. 1, three sub-data collection terminal devices are uniformly connected to each data collection terminal device, but this number can be arbitrarily set for each data collection device. Furthermore, there may be a data collection terminal device to which no sub-data collection terminal device is connected.

Furthermore, as shown in FIG. 2, since signals of different frequencies are sent out in time series from one data collection terminal device, these signals flO to f13 are not superimposed at the same timing. Therefore, even if the frequencies of the sub-data collecting devices connected to the same data collecting terminal device are close in frequency value, they will not be superimposed, and the frequency discrimination power will not deteriorate due to the superimposing. Therefore, f 10 ”
``' You could make f13 a narrow frequency band overall (
, the overall usable frequency band will expand.

In the above embodiment, the Fourier analysis device 2, the CPU
1 may be the same as the conventional one. Note that the Fourier analysis device 2 is preferably a parallel Fourier analysis device in view of the quick response of Fourier analysis.

〔effect〕

As described above, according to the present invention, even if the number of data collection terminal devices increases, data accompanying data transmission can be reliably identified.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a data collection method according to an embodiment of the present invention, Figs. 2 to 4 are signal waveform diagrams explaining the operation of the data collection method shown in Fig. 1, and Fig. 5 is a conventional data collection method. Configuration diagram, Figures 6 to 1
FIG. 1 is a signal waveform diagram illustrating the operation of the data acquisition method shown in FIG. 5. (Explanation of symbols) 1 ... CPU. 2...Fourier analysis device, 3...
- Terminal device group, 31-34... Data collection terminal device, 311-34
3...Sub data collection terminal device, 4...
... Signal line.

Claims (1)

[Claims] 1. A plurality of data collection terminal devices that transmit data indicating logic levels using a plurality of signals of different and corresponding frequencies, a signal line that connects the plurality of data collection terminal devices, and the signal line. a data collection device that is connected to the data collection terminal device via the data collection terminal device, receives data from the data collection terminal device, analyzes the frequency of the received data, identifies the data collection terminal device that sent it, and detects the logic level; In the data collection method, at least one of the plurality of data collection terminal devices is connected to a plurality of sub data collection terminal devices each of which transmits data indicating a logic level using signals of different and corresponding frequencies, and A data collection method characterized in that data of signals of these corresponding frequencies are sequentially sent to the signal line.