JPS5819047A - Transmitting system for analog quantity - Google Patents

Abstract

PURPOSE:To eliminate the need for an A/D converter of a terminal transmitter, by converting an analog quantity into a pulse width in the transmitter, transmitting it as a pulse signal, converting the pulse width of the signal received at a central controller into the analog quantity and performing A/D conversion. CONSTITUTION:Analog-pulse width converters 101 and 201 of transmitters 100 and 200 are respectively connected to analog quantity sensors 50 and 51. Transmission lines 102 and 202 are connected respectively to the converters 101 and 201 and the transmission lines 102 and 202 are connected with a transmission line 400 constituted in loop with glass fiber. A reception circuit 301 of a central controller 300 is connected to the transmission line 400 and an operation circuit 302 is connected to the reception circuit 301.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data transmission method between control devices located at mutually distant locations, and particularly to an analog quantity transmission method.

A conventional analog quantity transmission system has a configuration as shown in FIG. In other words, the transmission device 10 which is each terminal device
The transmitting circuit 12 of the transmission device 2° and the transmitting circuit 22 of the transmission device 2° are connected by a transmission line 5, and this transmission line 5 is formed in a loop shape.

A receiving circuit of the central control unit 30 is connected to the transmission line 5. Further, an analog quantity sensor 40 is connected to the transmission circuit 12 of the transmission device 10 via the A/D converter 11.
Further, the transmission circuit 22 of the transmission device 20 includes an A/D converter 2.
1, analog quantity sensors 41 are connected to each other. The arithmetic circuit 32 is still connected to the receiving circuit 31 of the central control device 30 .

In such a configuration, the analog quantity sensor 40
．． The analog quantity detected in 4.1 is converted into a digital quantity (hereinafter referred to as A, /D conversion) by the transmission device 10.20,
The signal is sent to a central control device 3o located at a location remote from the transmission devices 1o and 20 via a loop-shaped transmission line 5 that cascades the transmission devices 10 and 20. After performing desired control calculations, the central control device 30 sends a control output to an operating device (not shown) to achieve the purpose of control.

Generally, in such a control system, only one signal line is used as the transmission line 5 to improve economical efficiency.

By the way, in the field of automobile engine control, control using microcomputers (hereinafter referred to as MPU) based on information from various sensors has begun to be carried out, reducing fuel consumption (hereinafter referred to as fuel efficiency) more than ever before. It's starting to become possible. However, the amount of information required for control by the MPU is increasing, leading to an increase in the number of signal lines connecting various sensors and the MPU, and an increase in the weight of the vehicle, which is becoming a hindrance to reducing fuel consumption. From this perspective, the first
As shown in the figure, it has been proposed to adopt a control system using a loop-shaped transmission line to reduce the weight of the f-word line and to reduce the cost of wiring.

However, in such conventional transmission methods,
The transmission device 10.20 to which the analog quantity sensors 40 and 41 are connected includes an A/D converter 1 for A/D conversion.
1.21, each transmission device requires a large number of expensive A/D converters, which poses an economical problem.

An object of the present invention is to provide a transmission system for analog amounts that can be transmitted without using A, , /D converters used in each transmission device of a terminal.

The present invention converts an analog quantity into a pulse width within a transmission device and transmits it as the pulse signal, and converts the pulse width of the pulse signal received by a central control unit into an analog quantity and converts it into a digital quantity. The idea is to transmit data without using an A/D converter within the device.

Examples of actual guns of the present invention will be described below.

FIG. 2 shows an embodiment of the invention.

In the figure, an analog-pulse width converter 101 of a transmission device 10o and an analog-pulse width converter 201 of a transmission device 200 are connected to analog quantity sensors 50, 51, respectively. This analog-pulse width converter 101
A transmitting circuit 102 is connected to the analog pulse width converter 201, and a transmitting circuit 202 is connected to the analog pulse width converter 201. This analog-to-pulse width converter 102, 202 is connected to the transmission line 4.
00, and this transmission line 400 is made of glass fiber and formed in a loop shape. A reception circuit 301 of the central control device 300 is connected to this transmission line 400, and a transmission circuit 102.202 and a reception circuit 301 are connected thereto. This receiving circuit 30
1 is connected to an arithmetic circuit 302.

The transmission method in this embodiment is performed as shown in FIG. In the figure, (a) shows a signal configuration inside the transmission line 5, and (b) shows an example of a signal sent out from the transmission device.

First, the central control device 300 connects one transmission line to the transmission device R.
Figure 3 (I) shows the time available for I OO12,'00.
), the transmission devices 100 and 200 send out a signal consisting of a synchronization signal for time-division allocation, an address signal for identifying available transmission devices, and a portion for transmitting analog information. After the transmission device identifies its available time from the synchronization signal and the following address signal, it adds analog information to the designated location in the manner described below.

Ru.

The configurations of the transmission devices @100 and 200 in this embodiment are shown in FIG. 4, and the operating waveforms are shown in FIG. In addition, the A/PW converter 101 is as shown in FIG.
The transmitting circuit 102 is composed of a sawtooth wave generating circuit 110 and a comparator, and the transmitting circuit 102 is composed of a demodulating circuit 112 and a modulating circuit 113.

The demodulation circuit 112 receives the synchronization signal 5Y from the signal on the transmission line 400.
Address signal A D D R specifying NC and self;
When identified, it sends a signal 120 to the A/PW converter 101 as shown in FIG. Upon receiving the signal 120, the sawtooth wave generating circuit 110 starts operating and generates the signal 120.
make. The comparator 111 compares the signal 121 and the signal 122 from the analog quantity sensor 50 to generate a signal 123 as shown in FIG. 5(B) and sends it to the modulation circuit 113, which synchronizes the pulse width signal The signal is added after the address signal and sent to the transmission line 400.

Next, the configuration of the receiving circuit 301 in this embodiment is shown in FIG.
The operating waveforms are shown in FIG. 7, respectively. Receiving circuit 3
01 is a demodulation circuit 310 and a pulse width signal gate circuit 31
1. Consists of a sawtooth wave generation circuit 312, a sample hold circuit 313, and an A/D converter 314. Note that the transmitting circuit part is omitted because it is not the essence of this practical example. When the demodulation circuit 310 receives a signal 320 as shown in FIG. 7(A) from the transmission line 400, it outputs a signal 321 as shown in FIG. 7(B).
make. Based on this signal 321, the pulse width signal gate circuit 311 extracts only the pulse width signal portion corresponding to the analog quantity and generates a signal 322 as shown in FIG. The operation starts and a signal 323 as shown in FIG. 7 (l) is generated.
continues sampling the open signal 323 when the signal 322 is )7high, and when the signal 322 ceases to be J-7high, that is, becomes rOJ, the current value is held. In this way, the value Vi held by the sample hold circuit 313 corresponds to the pulse width, that is, the analog quantity detected by the analog quantity sensor 5o in FIG. As soon as the signal (7) 322 disappears, the A/D converter 314 outputs the signal 3.
24 is converted into a digital quantity and the arithmetic circuit 30 shown in FIG.
2 is information on feed control calculation.

Therefore, according to the practical example of the present invention, the transmission device does not require an expensive A/D converter. Figure 3 (
The address signal part shown in b) is a digital signal, but
Two types of analog signals can be mixed and transmitted to Digitano. Furthermore, since the analog quantity is converted into a pulse width signal and transmitted, it is less susceptible to the effects of noise induced in the transmission line.The transmission line 400 can be used not only as an electric signal but also as an optical fiber to transmit information using the amplitude of the transmission signal. This transmission method has the advantage that it can be used even in systems where it is difficult to ensure accuracy in transmission. In addition, in the actual example of the present invention, only the case where the transmission line 5 is loop-shaped has been described, but other systems may be used, and digital signals other than address signals may be added to the transmission signal. Furthermore,
It is clear that the present invention can also be applied when the data transmission line and the address transmission line are separate transmission lines.

(8) In the calculation example shown in FIG. 2, the pulse width can be converted into a digital value by the sawtooth wave generation circuit 312, the sample hold circuit 313, and the A/D converter 314, but a counter that counts clocks is used. Digital conversion is also possible.

As described above, according to the present invention, analog quantities can be transmitted and converted into digital values without providing an A/D converter used in each transmission device of a terminal.

[Brief Description of the Drawings] Fig. 1 is a diagram showing a conventional transmission control system, Fig. 2 is a diagram showing an embodiment of the transmission control system according to the present invention, and Fig. 3 is a diagram showing transmission signals in the embodiment of the present invention. 4 is a configuration diagram of a transmission device in an embodiment of the present invention, FIG. 5 is an operation waveform diagram of FIG. 4, FIG. 6 is a configuration diagram of a receiving circuit in an embodiment of the present invention, and FIG. The figure is a diagram showing the operating waveforms of FIG. 6. 111...Comparator, 110.312...Sawtooth wave generation circuit, 313...Sample hold circuit, 314
(9) ...Analog-digital converter. Agent Patent Attorney Akio Takahashi (10)

Claims (1)

[Claims] 1. A transmission line formed in a loop shape and made of glass fiber; a transmission device connected to the transmission line and converting an analog quantity detected by a sensor into a pulse width signal corresponding to the analog quantity; An analog quantity transmission method comprising: a central control unit connected to the transmission line and converting a signal transmitted as a pulse signal from the transmission device into an analog signal corresponding to the signal, digitally converted and output.