JPH0329018A - Analog signal input system for digital system - Google Patents

Abstract

PURPOSE:To decrease the number of wirings and to improve the noise resistance by adding an A/D converter and a circuit selection command device to a digital system together with a multiplexer for selection of circuits added to an analog system respectively and using an analog circuit and a circuit selection line to secure the connection between both systems. CONSTITUTION:An A/D converter 3 and a digital output device 7 which outputs a circuit selection command are added to a path 4 of a CPU board 14. At the same time, a multiplexer 2 is added to an analog input device 15 to alternately output the analog signals received from the channels CH1 - CHn. Then the connection is secured between the board 14 and the device 15 via an analog signal line 16 and a circuit selection line 17. As a result, two analog signal lines suffices together with four circuit selection lines 2 with 8CH and five lines 2 with 16CH respectively for connection secured between the board 14 and the part 15. In addition, a control signal line has just such a form that transmits both high and low voltage level signals. Therefore the superposition of noises is substantially neglected to the control signal line.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an analog signal input method to a digital system such as a CPU board, which inputs analog signals such as a large number of sensor signals to a digital system.

(Prior Art) For example, as a signal input method for inputting a large number of analog signals to a CPU board, two methods as shown in FIG. 3 or FIG. 4 are conventionally known.

In the system shown in Fig. 3, the CPU board 1 has a channel (C
H) A multiplexer 2 that manually inputs a large number of analog signals indicated by 1 to n, and a digital-to-analog converter (A/D) 3 that converts the analog signals appropriately selected and output from the multiplexer 2 into digital signals. By connecting this converter 3 to the CPU bus 4, analog signals can be directly taken in. CPU bus 4
In addition to the analog-to-digital converter 3, a CPU 5, a memory 6, and a digital output device (I/O) 7 for outputting a line selection command to the multiplexer 2 are connected to. Further, the analog signals of each channel CHI to CHn are manually inputted to the multiplexer 2 via an amplifier 8.

However, this method has a problem in that the analog input section generally takes up space, making the CPU board 1 larger. In addition, the signal from the sensor must be wired to the CPU board 1, and since the voltage level of the sensor's output signal is generally low, there is a high possibility that noise will be introduced, and the analog circuit is prone to noise generation. Because it was mounted on the same board as the digital circuit, care had to be taken when designing the circuit. Furthermore, if the ] board CPU is used in another system, and the number of manpower for that system exceeds the number of analog manpower on the CPυ board, the entire CPU board 1 must be rebuilt, which reduces development efficiency. was there.

On the other hand, in the system shown in FIG. 4, a buffer 10 connected to the CPU bus 4 is provided on the CPU board 9, and the CPU board 9
is connected via a bus 12 to an analog human power section (analog human module) 11 configured as a module. The analog human power module 11 includes an analog-digital converter 3 that converts the analog signal output from the multiplexer 2 into a digital signal, a buffer 13 that inputs this output and outputs it to the buffer 10 of the CPU board 9, and the buffer 13. A digital output device 7 is provided for manually inputting a line selection signal from the CPU board 9 via the digital output unit 7 to select a line for the multiplexer 2.

However, in this method, since the CPU board and the analog input module 11 are connected by the bus 12, there is a problem that the number of wires increases. Also, C.P.
If the mounting location of the U board 9 and the analog signal source are far apart, it is necessary to extend the CPU bus 4 or extend the analog signal. There was also a problem that it became weak against noise.

(Problems to be Solved by the Invention) As described above, in the analog signal manual system shown in FIG. 3, the CPU board 1 becomes large, the sensor signal length becomes long, and the noise resistance deteriorates. Further, there are problems in that special care must be taken in circuit design, and changes in the number of analog signals cannot be flexibly accommodated.

Further, the method shown in FIG. 4 uses a bus for wiring, so there are problems in that the number of wirings is large and noise resistance is poor.

Therefore, the object of the present invention is to provide an analog signal input method to a digital system that requires a small number of wiring lines, has high noise resistance, and can flexibly respond to changes in the number of analog signals.

The human-powered analog signal to digital system system of the present invention that solves the above problems is a manual system for manually inputting analog signals to the digital system, such as manually inputting analog signals such as a large number of sensor signals to the digital system such as a CPU board. A multiplexer is provided in the system to appropriately select an analog human input signal and output it to the digital system, and a line selection command device outputs a line selection command to the analog multiplexer to obtain a desired analog signal to the digital system. The present invention is characterized in that an analog-to-digital converter is provided for converting an analog signal inputted from the analog multiplexer into a digital signal.

(Function) In the present invention, an analog-to-digital converter and a line selection command device are provided in the digital system, a multiplexer for line selection is provided in the analog system, and the two are connected by an analog line and a line selection line.

Therefore, when changing the number of analog signals, only the analog system needs to be changed, and there is no need to change the digital system.

Furthermore, since both systems can be connected using an analog line and a line selection line, the number of signal lines is minimized and the problem of noise superposition is reduced.

(Example) Examples of the present invention will be described below.

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

In this example, the bus 4 of the CPU board 14 is provided with an analog-to-digital converter 3 and a digital output device 7 that outputs a line selection command, and the analog input device 15 is connected to each channel CHI to CH.
A multiplexer 2 is provided for selectively outputting an analog signal inputted from n, and the two are connected by an analog signal line 16 and a line selection line 17.

Specifically, as shown in FIG. 2, the analog signal line 16 consists of two lines, a ground line and a signal line, and is appropriately equipped with an output amplifier 8A and a human amplifier 8B. The line selection line 17 is formed from a ground line and the minimum control signal line depending on the number of channels (for example, three for 8CH and four for 16CH).

In the above configuration, in this example, the CPU 5 specifies a required channel number according to the task, sends it to the line selection line 17 via the digital output device 7, and sends it to the multiplexer 2.
A line selection is made at , and a predetermined analog signal is sent to the analog signal line 16. By giving a fixed value to the amplification factors of the amplifiers 8A and 8B in advance, the CPU 5 can obtain a predetermined analog quantity by giving the reciprocal of this multiplication factor to the input value.

Furthermore, if the number n of analog signal channels increases, it is sufficient to change only the analog input section 15 without changing the design of the CPU board 14.

As described above, in this example, the connection between the CPU board] 4 and the analog input section 15 includes two analog signal lines and two line selection lines.
For 8CH, only 4 wires are required, and for 16CH, only 5 wires are required, making it possible to significantly reduce the number of connection wires.

Further, since the control signal line is configured to simply send High and Low voltage level signals, noise superimposed on this line hardly poses a problem.

Furthermore, even if the CPU board 14 and the analog input section 15 are separated, the analog input section 15 sufficiently amplifies the weak signal from the sensor and then sends the analog signal to the analog-to-digital converter 3 of the CPU board 14. It has high noise resistance against external noise compared to .

Furthermore, even if it is desired to completely isolate the CPU board and the analog input section 15, it can be achieved with a minimum number of parts because the number of connection lines is smaller than in the conventional system.

In addition, since the analog human power section 15 has almost no digital section, it is relatively easy to use the analog section 15 compared to the conventional method.
can be designed, and even if the number of input channels increases, it can be handled with minimal circuit changes.

The present invention is not limited to the above-mentioned embodiments, but can be implemented in any appropriate manner by making appropriate design changes.

[Effects of the Invention] As described above, the present invention is an analog signal input method to a digital system as described in the claims, so the number of wiring is small, noise resistance is high, and the number of analog signals can be changed. can respond flexibly.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an analog signal manual system according to an embodiment of the present invention, Fig. 2 is an explanatory diagram showing details of the connection line section in Fig. 1, and Figs. 3 and 4 are both conventional FIG. 2 is a circuit diagram showing an analog signal manual system. CHI to CHn...Manual channel 2...Multiplexer 3...Analog-to-digital converter 4...CPU bus 7...-Digital output device 14...CPU board 16...Analog signal line 17...・Circuit selection line

Claims (1)

[Claims] An analog signal input method to a digital system that inputs analog signals such as a large number of sensor signals to a digital system such as a CPU board, and a multiplexer that selects an appropriate line for the analog input signal to the analog system and outputs it to the digital system. a line selection command device that outputs a line selection command to the analog multiplexer in order to obtain a desired analog signal to the digital system; and an analog converter that converts the analog signal input from the analog multiplexer into a digital signal. An analog signal input method to a digital system characterized by the provision of a digital converter.