JPH0131816B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data collection method suitable for a case where the number of transmitted data per terminal is extremely small.

Figure 1 shows three types of data collection systems; in each figure, 1 is a data collection device;
2 is a data transmission terminal, and 3 is a transmission line. Data transmission terminal 2 is relay contact ON/OFF, power switch ON/OFF, fire alarm ON/OFF
It captures digital data such as data and sends it to the central data collection device 1 using an appropriate method.The data collection device 1 decodes the signal sent from the terminal device 2 and stores the data on the terminal side. The information may be displayed, and in some cases, an alarm may be issued.

In the system configuration shown in Figure 1A, the central data collection device 1 and each terminal device 2 are individually wired in a 1:1 ratio, and although the configuration is simple, the wiring cost of the transmission line 3 is high. Become.

In the system configuration shown in FIG. Since they are connected by a real transmission line 3, the wiring cost is reduced. On the other hand, software consideration is required to avoid a situation in which two terminal devices transmit duplicate signals (hereinafter referred to as "collision").

In the system configuration shown in FIG. It also becomes possible to exchange signals between the two. In this system, the wiring cost of the transmission line 3 is higher than that of the system shown in FIG. 1B, but the data transmission function is significantly higher.

FIG. 2 shows a general configuration example of the data transmission terminal 2. As shown in FIG.

microprocessor 4, read-only memory 5,
Random access memory 6, LS for data transmission and reception
17 and a data input/output LS 18 are connected via a bus line 9.

The microprocessor 4 temporarily stores information that comes in from the outside via the input terminal 10a, and then immediately sends it to the data collection device 1 via the output terminal 10b, and at an appropriate timing, input information connected to its own terminal. Information is captured via the terminal 11 and sent to the data collection device 1 via the output terminal 10b.

FIG. 3 shows the state of signals entering the central data collection device 1.

Figure 3A shows the case of a rather simple transmission method,
Signals 12 from each terminal 2 arrive at random timing. As a result, the signals 12 and 13 from the two terminals may collide, and in this case, both data become invalid. Although there are such drawbacks, this method is applicable when the data transmission time per terminal is short or when the frequency of data generation is low because the software of the terminal device is simple.

FIG. 3B shows a commonly used method in which the signals 14 from each terminal 2 arrive without collision. The way to prevent collisions when using a system like Figure 1 B is to have the terminal receiving a signal wait temporarily without transmitting its own signal, and then transmit its own signal after transmitting the received signal. Such measures are necessary. In addition, in a system such as that shown in FIG. 1C, it is common that only designated terminals perform transmission based on commands from the central data collection device 1.

In any case, if we look at the data transmitted from one terminal in more detail, it consists of a header section a, data b, an error check section c, etc. The header section a includes a code indicating the start of data, a transmitting terminal address, etc., and the error check section c also includes a parity check code, a CRC code, etc., and a code indicating the end of the transmitted information.

The data transmission method described above is suitable for cases where there are a large number of terminals, the amount of data to be transmitted per terminal is large, and transmission is performed frequently. However, in reality, there are many systems in which the number of terminals, the number of data transmitted per terminal, and the frequency of transmission are small.

In such a case, it would be very uneconomical to use a data terminal device as shown in FIG.

For example, if a terminal device like the one shown in Figure 2 is used in a system that centrally monitors the operation status of fire alarms in a building, the alarm will be activated every second, compared to a system that only activates once a year. You will be applying hardware that is capable of transmitting thousands of bits of data, and that hardware will be ``idling'' most of the time. Furthermore, even though there are a wealth of additional functions available using a microprocessor, they are not often utilized.
Furthermore, the number of bits in the header section may end up being far greater than the number of bits in the data to be transmitted.

The present invention has been made based on the above, and an object of the present invention is to provide a highly reliable data collection method that can collect decimal data at low cost.

That is, the present invention uses a system configuration as shown in FIG.
Bits are relayed sequentially from the terminal farthest from the data collection device, and each terminal adds its own data to the beginning of the received data and sends it to the data collection device.Terminals with no received data are in this state. This feature is characterized in that by detecting this, self-data is transmitted at a sufficiently long constant cycle using an internal timing signal.

An overview of the present invention will be explained with reference to FIG. It is assumed that the number of data transmitted from each terminal device is 1 bit, and data "1" is associated with a wide pulse width, and data "0" is associated with a narrow pulse width.

When data #1 is transmitted from the terminal farthest from the data collection device, the next terminal adds data #2, and each terminal sequentially adds its own data. If the number of terminals is N and the length of 1 bit of data is Tb, the total data length is NTb. Therefore,
This operation is repeated again at a repetition period Tf that is sufficiently long compared to NTb.

For this repetition, a timing pulse generator (periodic
Tf) and transmit its own data #1 at the rising edge of this timing generator.

The data acquisition device discriminates the pulse width of the received signal and sequentially stores its contents in memory. When the Nth data #N is received, the input signal disappears and a pause period (length T' = Tf - NTb) begins. As a result, the data collection device enters a standby state, and once again it becomes possible to uniquely identify the next signal as coming from the nearest terminal.

In this way, even if the input data does not have an address or a heading, it is possible to determine which data is transmitted from which terminal.

By the way, in the above-mentioned method, if one terminal device malfunctions, data from not only that terminal device but also previous terminal devices will not be transmitted, and furthermore, data from subsequent terminal devices will not be transmitted. Terminals located in the network will also be unable to obtain timing for transmitting their own data, and as a result, a failure in one terminal will spread to the entire system.
Therefore, in the present invention, each terminal is provided with a function of detecting that there is no received data and generating an internal timing signal, and transmits its own data based on this.

Furthermore, in the present invention, by counting the total number of received pulses with the data collection device, it is also possible to detect whether or not there is a failure in the terminal device and the location of the failed terminal device.

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 5 to 8.

FIG. 5 shows the circuit configuration of the terminal, and FIGS. 6 and 7 show its operation time chart. In FIG. 5, 50 is an input terminal, 51 is an output terminal, 52 is a data input terminal, 53 is an extendable monostable multivibrator, 54 is a data generation circuit, 55 is a 1-bit delay circuit, and 56 is an output OR
Gate 57 is an internal timing generation circuit.
The data generation circuit 54 includes monostable multivibrators 540, 541 and a data selection gate 542,
543, and the internal timing generation circuit 57 includes an extendable monostable multivibrator 570, a clock generation circuit 571, and an inhibition gate 5.
72 and an output gate 573.

First, a case where all terminals are operating normally will be explained.

A signal entering the input terminal 50 passes through a 1-bit delay circuit 55 and is output from the output OR gate 56 to the output terminal 51.

On the other hand, the monostable multivibrator 53 is driven at the rising edge of the first pulse of the input signal, and the data generation circuit 54 is driven by its output. The data generation circuit 54 outputs pulses of different shapes to the output OR gate 56 depending on whether the self data input to the self data input terminal 52 is "1" or "0".

Here, the operation will be explained by taking as an example the third terminal device from the farthest terminal device from the data collection device.

In this case, two pulses will come into the terminal, a wide pulse for data "1" and a narrow pulse for data "0". It is assumed that an input signal as shown in FIG.

First, input signal 60 is delayed by 1 bit Tb by 1-bit delay circuit 55 to obtain signal 61. A signal 64 is obtained by adding to this signal 61 a signal 63 having self-data synchronized with the rise of the first bit of the input signal 60.

Meanwhile, extendable monostable multivibrator 5
3 (metastable time Tm) and sells the signal 62. This monostable multivibrator 53 detects the rising edge of the first bit of input data, and converts the metastable time Tm into the total input data length NTb (N:
By setting the timing signal to be sufficiently longer than the total number of terminal devices (Tb: 1 bit length) and sufficiently shorter than the data transmission cycle Tf, the timing signal for self-data generation can be used only at the rising edge of the first pulse of input data. It can be supplied to the generation circuit 54.

In the data generation circuit 54, a monostable multivibrator 540 that generates a narrow pulse and a monostable multivibrator 541 that generates a wide pulse are simultaneously driven by the rise of the signal 62, and the data selection gates 542 and 543 drive the self-data If is "1", a wide pulse is output to the output OR gate 56, and if it is "0", a narrow pulse is output to the output OR gate 56.

Note that if there is no failure in any terminal device, the extendable monostable multivibrator 570 is driven by the input signal, so as long as the input signal exists, the output of the monostable multivibrator 570 will be at a high level. , the output of the cloak generator 571 is output to the output gate 5 by the function of the inhibit gate 572.
I never go out in 73.

Next, a case will be described in which a certain terminal device malfunctions and input signals no longer enter the other terminal devices. In this case, due to the interruption of the input signal, the output of the monostable multivibrator 570 becomes low level, and the output of the clock generator 571 passes through the output gate 573 and drives the data generation circuit 54 to transmit its own data. It turns out.

70 in FIG. 7 is an input signal to a certain terminal, and 700, 701, 702, . . . indicate data arriving from the previous terminal. These data arrive in groups of several bits every time Tf.

By setting the metastable time τ ₀ of the extendable monostable multivibrator 570 driven by the input signal to a value slightly larger than the period Tf in which the input signal arrives, the input signal arrives every time Tf. As long as the output of the monostable multivibrator 570 remains high.

However, the input signals 702, 703 in FIG.
If the signal is interrupted as shown in 704, the signal 7
It falls to a low level as shown in 2 and remains in this state until the next input signal comes.

On the other hand, the clock pulse 71 is constantly transmitted from the clock generator 571, and when the output of the monostable multivibrator 570 becomes low level, an internal timing signal 73 is obtained by the action of the inhibit gate 572.

If self data (742, 743 in FIG. 7) is transmitted at the rising edge of this internal timing signal 73, the signal 74 becomes possible, and data transmission becomes possible.

The period T'f of the clock pulse 71 is generally set equal to the period Tf of the signal arriving from the outside, but it may be different.

When the input signal from the adjacent terminal device comes again, the monostable multivibrator 570
Since the output returns to high level, the internal timing signal is no longer output due to the function of the inhibit gate 572, and the normal operation is resumed.

Note that when one terminal device fails, all the terminal devices on the data collection device side from that terminal device simultaneously output an internal timing signal and try to send out their own data, but immediately after that, no terminal device is connected to any terminal device. Even then, a signal from the previous terminal (driven by an internal timing signal) arrives and normal operation immediately resumes. Then, after a short period of time has elapsed, data continues to be sent using the internal timing signal of only one terminal on the data collection device side compared to the failed terminal.

FIG. 8 shows the circuit configuration of the central data collection device.

80 is an input terminal, 82 is a pulse width discriminator/series/parallel exchanger, 82 is a microcomputer system,
86 is a display device, and the microcomputer system 82 consists of a bus line 83, a microprocessor unit 84, and an LSI 85 for connecting peripheral devices.

The input signal enters an input terminal 80, is exchanged in parallel by a pulse width discriminator/series/parallel exchanger 81, and is temporarily stored in a buffer memory. The output of this memory is the bus line 8 of the microcomputer system 82.
3 by the microprocessor unit 84. Further, the read data is sent to the display device 86 via the peripheral device connection LSI 85, where the status of the data sent from each terminal device is displayed.

As explained above, according to the present invention, highly reliable data transmission is possible even with a very simplified system configuration, and data collection without collision can be realized at low cost.

Furthermore, each terminal device can be made into a single-chip IC.

[Brief explanation of drawings]

Fig. 1 is a schematic explanatory diagram of three examples of data collection systems, Fig. 2 is an explanatory diagram of a conventionally known terminal device, and Fig. 3 is an explanatory diagram of a signal transmitted from a terminal device in the conventional system. , FIG. 4 is an explanatory diagram of a signal transmitted from the terminal device according to the present invention, FIG. 5 is an explanatory diagram of an example of the circuit configuration of the terminal device according to the present invention, and FIG.
7 and 7 are explanatory diagrams of operation time charts according to the present invention, and FIG. 8 is an explanatory diagram of an example of the circuit configuration of the data collection device according to the present invention. 1: Data collection device, 2: Terminal, 3: Transmission line.

Claims (1)

[Claims] 1. A data collection device and a plurality of terminal devices are connected in a straight line via a unidirectional transmission line, and the data is sequentially relayed and transmitted from the terminal device furthest from the data collection device. In the collection method, the oscillation data from each terminal is 1 bit, each terminal adds 1 bit of its own data to the beginning of the received data and transmits it to the data collection device, and terminals with no received data do this. Sending out self-data using internal timing signals by sensing the condition;
A data collection method characterized in that the data collection device discriminates the data of each terminal by arranging the received data in order from the nearest terminal to the farthest terminal. 2 Each terminal delays the data sent from the previous terminal by 1 bit before sending it to the next terminal, and also delays the data sent from the previous terminal by 1 bit. 2. The data collection method according to claim 1, wherein self data is added to the time slot of the data collection method.