JPH0459679B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data acquisition device that sequentially receives a plurality of input signals, performs predetermined signal processing, and then displays or prints the signals.

In conventional data acquisition devices, when acquiring input signals, when the input types are different, such as a resistance input signal such as a resistance temperature detector, and a voltage input signal such as a thermocouple, etc., and the signal level is also different, each input signal is Grouped by input type, for example, No. 1 to No. 10 are voltage input signals, No. 11 to No. 20 are
Until now, input points (measurement terminals) were assigned to signals like resistance input signals. Therefore, in addition to switching the input signal, it is also necessary to switch the type of input, which makes the switching circuit complex and expensive, and it is not possible to connect any type of input to any measurement terminal. There were flaws.

The present invention has been made in view of the above circumstances, and its object is to provide a data acquisition device in which either voltage measurement or resistance measurement can be arbitrarily selected using any measurement terminal.

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a structural diagram showing an embodiment of the present invention, and FIG. 2 is a structural diagram of a terminal board used in the present invention. In the figure, E ₁ and E _o indicate voltage input signals such as a thermocouple, and Pt ₁ and Pt ₂ indicate resistance input signals such as a three-wire platinum resistance temperature detector. tm ₁ ~ tm ₃ (m
=1 to n) are measurement terminals that are a set of three terminals, each of which is connected to a voltage input signal or resistance input signal, and each measurement terminal constitutes a terminal board T as shown in Figure 2. ing. S ₁ to S _o are each a pair of two switches, and IS is an input switch that sequentially switches and receives signals according to commands from a control circuit, which will be described later. IS is a control circuit that controls constant currents I ₁ and I ₂ of the constant current circuit. A is an amplifier that can change the gain to G ₁ and G ₂ according to the command of the control circuit;
AD is an analog-to-digital converter. In addition, M is a memory that stores the operating program, the type of input signal for each measurement terminal, processing/arithmetic formulas, etc., and the CPU calculates the measured data according to the contents of the memory M and outputs the processed data. CC is a control circuit that outputs command signals for taking in input signals, switching the gain of amplifier A, starting conversion of A/D converter, etc. according to commands from the central processing unit CPU. ,
DP is a display device that digitally displays processing data.
P is a printer that prints processed data.

In the data acquisition device configured in this manner, before starting measurement, the type of input signal connected to each measurement terminal is stored in the memory M by a setting device (not shown). In this example, measurement terminal No. 1 is a voltage input signal, measurement terminal No. 2 is a resistance input signal, and measurement terminal
Set and memorize that No. 3 is a resistance input signal and measurement terminal No. n is a voltage input signal. Note that all measurement terminals are in the same state, and in the case of a voltage input signal, the upper two terminals are connected to +, as shown in the terminal board T in Figure 2.
-, and in the case of a resistance input signal, all three terminals are used, but in this case, it is sufficient to connect any input signal to any measurement terminal and memorize its contents, and the setting terminal can be used in common. Can be done.

When the above setting operations are completed, change to the measurement state and start data acquisition. According to the operation program stored in the memory M, the central processing unit
The CPU issues a command to the control circuit CC, and the control circuit CC outputs a command signal _C1 based on the command to turn on the input switch _S1 . At this time, since the input signal to the measurement terminal No. 1 is the voltage input signal _E1 , the current supply switch IS is not driven by the command signal _C1 and remains in the off state. The voltage input signal E ₁ taken in from the input switch S ₁ in this way is amplified by the amplifier switched to a predetermined gain G ₁ by the command signal C ₂ of the control circuit CC, and the pressure is
The signal is input to the converter AD, and at the same time, A/D conversion is started by the command signal _C3 of the control circuit CC. A/D
The measurement data converted into digital signals by the converter AD is sent to the central processing unit CPU, and is stored in the memory M.
Calculations such as linearization are carried out according to the type of input signal (type of thermocouple) according to the program stored in the terminal, and the processed data is sent to the display device DP and the printer P. The measured value is displayed and printed.

Next, according to the program in the memory M, the command signal _C1 of the control circuit CC turns off the input switch _S1 and turns on the input switch _S2 . At this time, the measurement terminal
Since the input signal of No. 2 is the resistance input signal Pt ₁ ,
The current supply switch IS is driven by the command signal _C1 and turned on. Therefore, constant currents I ₁ and I ₂ are supplied to the resistance input signal Pt ₁ , and a voltage drop corresponding to the resistance value is input to the amplifier A. At this time, the gain of amplifier _A is
It has been switched to G ₂ . The output which is amplified _twice by G by this amplifier A is converted into a digital signal,
The signal is subjected to predetermined signal processing and sent to the display DP and printer P, where it is displayed and printed as the measured value of measurement terminal No. 2.

Thereafter, the same operation as described above is repeated from measurement terminal No. 3 to measurement terminal No. n, and data acquisition of a large number of input signals can be performed.

As described above, the present invention stores in advance the type of each input signal connected to the measurement terminal,
When taking in each input signal, the voltage input signal is taken in as is, and the resistance input signal is taken in after being converted to voltage by supplying a constant current, so you can arbitrarily select either voltage measurement or resistance measurement with any measurement terminal. This is a data acquisition device. Therefore, the measurement terminals can be shared and the switching circuit of the input section can be simplified, so that an inexpensive and highly reliable device can be constructed.
Furthermore, since any type of input signal can be connected to any measurement terminal, there is also the effect that there is a large degree of freedom in determining the number of locations (number of measurement terminals) for each type of input.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram showing an embodiment of the present invention, and FIG. 2 is a structural diagram of a terminal board used in the present invention. E ₁ , E _o ... Voltage input signal, Pt ₁ , Pt ₂ ... Resistance input signal, I ₁ , I ₂ ... Constant current, T ... Terminal board, t ₁₁ ...
t _o3 ... terminal, S ₁ ~ S _o ... input switch, IS... current supply switch, A... amplifier, M... memory,
CC...Control circuit, AD...A/D converter, CPU
...Central processing unit.

Claims (1)

[Claims] 1. In a data acquisition device that sequentially receives a plurality of input signals from a measurement terminal of a terminal board and displays or prints them after predetermined signal processing, a memory that stores in advance the type of each input signal connected to the measurement terminal, and a memory for each input signal When taking in the voltage input signal, the voltage input signal is taken in as is, and the resistance input signal is converted to voltage by supplying a constant current via the constant current supply switch and then taken into the central processing unit. In addition to making it possible to measure resistance, a measurement terminal consisting of three terminals is used for each input signal on the terminal board, and all three terminals are used when measuring resistance.
A data acquisition device characterized in that it is configured to use only two terminals when measuring voltage so that a terminal board can be shared.