JPS6314369B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data acquisition device using an analog-to-digital converter (hereinafter abbreviated as an A/D converter).

Conventionally, this type of data acquisition device has a signal conditioner 2 consisting of an amplifier, a waveform generator, and an attenuator, a multiplexer 3, as shown in FIG.
It is composed of an A/D converter 4 and a data processing device 7 that stores and processes digital values.
The signal to be measured inputted as input n is subjected to a predetermined circuit conversion process in the signal conditioner 2 and connected to the multiplexer 3, and then only the signal selected by the switching control signal 8 from the data processing device 7 is A/D converted. The data was converted into a digital value by the device 4 and then input to the data processing device 7.

With this configuration, fluctuations in the amplification factors of the signal conditioner 2 and the A/D converter, generation of offset voltage, etc. are directly input to the data processing device 7 as measurement errors, so the signal conditioner 2 and the There is a drawback that not only the initial adjustment of the A/D converter 4 but also periodic fine adjustment during operation is essential.

An object of the present invention is to provide a data collection device that does not require these initial adjustments or periodic fine adjustments during operation.

In order to solve the above drawbacks, the present invention provides a reference voltage generator that outputs a predetermined output voltage O(v) or Es(v) under external control, and a reference voltage generator that outputs a predetermined output voltage O(v) or Es(v) under external control, and a reference voltage generator that outputs a predetermined output voltage O(v) or Es(v). a signal conditioner that takes the output of the switch as input and performs a predetermined linear circuit conversion;
An operation realized by an A/D converter that takes the output of the signal conditioner as input and linearly converts it into a digital value, and a data processing device that takes the digital value output of the A/D converter as input and performs a predetermined operation. This is a data collection device consisting of a device and a device.

Next, one embodiment of the present invention will be described with reference to the drawings.

FIG. 2 shows an embodiment of the present invention, in which 1 is a relay that switches between the voltage to be measured and the reference voltage, 2 is a signal conditioner, 3 is a multiplexer that switches a plurality of inputs, and 4 is a relay that switches the output voltage of the multiplexer. An A/D converter performs D conversion, 5 is a reference voltage generator, and 6 is a data processing device.

Here, if the digital values obtained by linearly A/D converting the reference voltages O(v), Es(v) and the voltage to be measured Ex(v) are X, Y, and Z, (2), (3), ( 4) The formula holds true.

X=N・G・e+d……(2) Y=N・G・(e+Es)+d……(3) Z=N・G・(e+Ex)+d……(4) By rearranging these equations, equation (5) is obtained.

Ex=Z-X/Y-X×Es......(5) However, N is the coefficient of the A/D converter and N counts/1 (v). Yona's input conversion offset voltage d is the output offset value of the A/D converter, that is, the digital value X obtained by A/D conversion,
If the arithmetic unit performs the calculation shown in equation (5) using the values of Y, Z, and predetermined voltage Es (v), the voltage to be measured can be determined regardless of the amplification factor or offset voltage.
Ex(v) can be obtained and the object of the present invention can be achieved.

Next, the operation of the block shown in FIG. 2 will be explained. First, data processing device 6 sends switching control signal 9 to switch relay 1 to the reference voltage side, and also sends switching control signal 8 to switch multiplexer 3. S
1 side, and further sends a switching control signal 10 to control the output of the reference voltage generator 5 to O(v), and receives and stores the digital value X from the A/D converter 4. Next, the data processing device 6 sends out a switching control signal 10 to control the output of the reference voltage generator 5 to become Es(v), and then outputs the output from the A/D converter 4.
The digital value Y is received from and stored. Next, the data processing device 6 sends a switching control signal 9 to switch the relay 1 to the voltage to be measured side, converts the voltage to be measured Ex (v) applied to the input 1 from analog to digital, and receives the digital value Z. Then, using the memorized values of X and Y,
Execute the calculation in equation (5) to obtain the value of Ex(v). Thereafter, the multiplexer 3 is sequentially switched to S2 to Sn, and the voltages to be measured at inputs 2 to n are measured in the same manner.

As explained above, the present invention switches the voltage to be measured and the reference voltage using a switch, and uses the same signal path to connect the A/D.
By converting the digital value and calculating the voltage to be measured by performing arithmetic operations on the digital value, the measured value is not affected by the amplification factor or offset caused by temperature or aging of the signal conditioner or A/D converter. Since the voltage is not affected, there is no need for initial adjustment or periodic fine adjustment during operation, it does not matter if the amplification factor fluctuates or there is an offset, and the known reference voltage is A/D converted. Therefore, it is effective in detecting functional failures of signal conditioners and A/D converters.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a conventional data collection device, Figure 2
The figure is a configuration diagram of an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Switcher, 2...Signal conditioner, 3...Multiplexer, 4...A/D converter, 5...Reference voltage generator, 6 and 7...Data processing device, 8, 9 and 10 ...Switching control signal.

Claims (1)

[Claims] 1. A reference voltage generator that generates at least two reference voltages, a switch that selects and outputs one of the reference voltages and the voltage to be measured, and a signal that has a linear transfer function that receives the output of this switch as input. A conditioner, an analog/digital converter that linearly converts the output of this signal conditioner into a digital value and outputs it, and
The digital value of the voltage to be measured obtained as the output of the digital converter and the digital values of at least two reference voltages are each input, and the signal conditioner and the analog-to-digital converter combine the digital values of the at least two reference voltages. A data collection device comprising: a calculation unit that calculates a transfer characteristic value by calculation, performs a correction calculation on the digital value of the voltage to be measured based on the calculated value, and outputs the true measurement value of the voltage to be measured. Device.