JPS6050417A - Automatic testing apparatus for industrial instrument - Google Patents

Abstract

PURPOSE:To stabilize the output in the shortest time as possible and to perform measurement quickly, by keeping a value, so that it is larger than the original testing signal for a initial specified time period, during which the testing signal is inputted to an instrument under test. CONSTITUTION:A CPU14 generates a specified signal in accordance with a program (a) and a waveform list (b) of a memory 15. The signal is inputted to an I/O interface 13, a DA converter 16, and a signal generating part 17. A signal E1, whose rising is quicker than the original testing signal, is inputted to an instrument under test. The output signal from the instrument under test is inputted to the CPU14 through a measuring part 11, an AD converter 12, and the I/O interface 13, and pass or fail is judged. The result is displayed on a display part 18 and a printing part 19. Thus the output is stabilized in a short time, and the measurement is performed quickly.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to automatic test equipment for industrial instruments used in the measurement field, particularly industrial instruments that are characterized by the test input signal input to the instrument under test. Regarding automatic test equipment.

(b) Conventional technology industrial bars include those that use either electrical signals or pneumatic signals as input/output signals, and those that use electrical signals as input/output signals.
There are some that use air pressure signals as output signals, and others that do the opposite. Conventionally, to measure the linearity accuracy of these industrial instruments, for example, 0% of the span of the instrument was measured from the outside.
Signals corresponding to 25%, 50%, 75%, and 100% were input, the corresponding output signal values were measured, and the accuracy was calculated from the values. This external signal is
Go motion switching or fixed time (tl) as shown in Figure 1.
Alternatively, the output of the instrument under test was checked, and when the output became stable, the data of the two instruments under test was sampled, and the next test value was input to the instrument under test. However, since all of these test signals give a constant value such as 0%, 25%...100% for a certain period of time, it is difficult to connect the mV converter to the input of a first-order delay with a long time constant such as an isolator. However, in the case of a meter that has two types of data, it inevitably takes a long time to provide one piece of data, which has the disadvantage of not being able to perform quick measurements. In other words, if the time constant is T, the times at which the step response becomes 99%, 99.9%, and 99.99% of the steady value are 4.6 T, 6.9 T, and 9.2 T, respectively. Assuming that T is 1 second and the accuracy of the instrument is 0.5%, it took 6.9 seconds to reach 99.9% rail.

(c) Purpose In view of the above, it is an object of the present invention to provide an automatic industrial instrument testing device that can stabilize the output in as short a time as possible and perform measurements quickly.

(D) Structure In order to achieve the above object, the automatic industrial instrument testing device of the present invention generates a test signal at a value larger than the value originally added as a test signal for a certain period of time at the beginning of inputting the test signal to the instrument under test. This ensures that the output of the instrument under test reaches a predetermined value quickly.

In other words, the industrial instrument automatic testing device of the present invention includes a signal generator that outputs a test signal to be input to the instrument under test;
A measuring section that receives the output signal of the instrument under test and performs test measurements, and a measuring section that receives the output signal of the instrument under test, and a value KEi that is larger than a predetermined test input signal Ei, and a value KEi that is larger than a predetermined test input signal Ei, in response to different delay time constants of the various instruments under test. a waveform list storage means for pre-storing a waveform pattern including an output time ゛F; a means for inputting a delay time constant of the instrument under test; and a means for storing the waveform list in response to the input delay time constant of the instrument under test. means for deriving the corresponding KEi value and time T from the storage means; the signal generating section outputs a signal of KEi at the measurement start time; and after time T, a signal of Ei is outputted; I'm trying to make it happen.

(E) Examples Hereinafter, the present invention will be explained in further detail with reference to Examples.

FIG. 2 shows a schematic connection diagram when testing a meter under test using the automatic test device for industrial meters according to the embodiment. This shows a state in which an output signal EO is derived from the instrument under test 2 in response to the signal EI, and is taken into the automatic test equipment 1 and measured.

FIG. 3 is a block diagram of an industrial instrument automatic testing device showing one embodiment of the present invention. In the figure, reference numeral 11 denotes a measurement unit that receives an output signal (for example, an electrical signal) EO from the instrument under test. After that, CPU (microprocessor) 1
It is now being incorporated into 4. Reference numeral 15 denotes a memory for storing programs for the CPU 14, a waveform list described above, and the like. Reference numeral 11 denotes a signal generating section that generates a test signal EI to be input to the instrument under test. The test signal El outputted from the signal generator 11 is an electric signal or a pneumatic signal, and C
This corresponds to a signal that is output as a digital signal from the PU 14, passed through the I10 interface I3, converted into an analog signal by the D/A converter 16, and applied to the signal generator 17.

As shown in FIG. 4, the waveform of this test signal El is such that the rising edge 1&T1 is KEi, which is the true value of the original test signal E, and after that, the waveform is doubled to a predetermined value Ei.

The above K and TI are determined by the delay time constant of the instrument under test, and the K and TI corresponding to various time constants are
The values of are stored in the memory 15 in advance as a waveform list. Reference numeral 18 indicates a display section for displaying the measured signal or generated signal, and 19 indicates a printout of the measured signal or generated signal. Reference numeral 20 denotes a setting section, in addition to keys for setting the types of electrical signals and pneumatic signals of the measuring section, generation section, etc., a known specification key for specifying dirt if the time constant of the device under test is known; It is also equipped with a key to manually set the time constant.

In accordance with the program stored in the memory 15, the CPU 4 executes a series of processes for test measurement, such as generation of test input signals and acquisition of measurement signals.

Next, the test and measurement processing operation of the industrial instrument automatic testing apparatus configured as follows will be described with reference to the flowchart shown in FIG. Note that a mV converter will be taken as an example of the instrument under test. If the time constant of the mV converter is known, the measurer uses the setting section 20 to designate the known time constant and set the time constant. If the time constant is unknown, do not set the known specification.

When the operation starts, first in step ST1 it is determined whether the time constant of the meter under test, that is, the mV converter is known. If known designation is not made in the setting section 20, this 'I'lJ constant becomes No, and then in step ST2, a signal of a certain magnitude, for example, a signal of 100%, is sent to the instrument under test [Fig. 6 (a)] Reference]. Then, the output waveform of the test object in response to this input waveform (see FIG. 6(b)) is monitored (step 5T3). This monitor calculates the time constant of the instrument under test. Then, the process moves to the next step ST4.

In step STI, if the time constant is known, step S
Processing in T2 and ST3 is not necessary, and step ST is performed immediately.
Move on to 4. In step ST4, the optimum test input signal waveform is extracted by referring to the waveform list in the memory 15 based on the time constant that has been set or input or calculated by inputting the waveform. The test input signal waveform for each test is as shown in FIG. 6(c), and the height h and width tw of this signal waveform correspond to the time constant of the -order lag. This test input signal is the sixth
When the waveform shown in Figure (c) is input to the instrument under test, its output waveform becomes the waveform shown in Figure 6 (d), which quickly reaches the predetermined level. Execute the linearity measurement as follows (Step 5T5)
.

Here, one example of a method for determining the input waveform El will be explained with reference to FIG.

As shown in Fig. 4, a signal that is α% larger than the predetermined input value is input until time '1゛1 has elapsed from the rise of the waveform, the output rises faster, and the predetermined input Ej is increased just before the steady value. , the output EO in this case is EO=KEi (1-e
-〒)4-fEi-KEi-工! It can be expressed as J"r (1-e")l (1-e cho).

Now, for example, if the input KEi signal is applied for a time T1 to speed up the rise of the output waveform so that the output value Ea becomes 99% of the steady value at time T1, and TI=T, then
That is, if time T1 is made equal to time constant T, then K (1-G-') = 0.99, -, = 1.6. Also, assuming that the measurement is performed when the final value reaches 99.9% of the steady value, 0.99Ei+ (1-0,99)Ei=1''1 (1-e T ) -0,999Ei Solve this. (However, TI='F) t = 3t3 T This t indicates the time until the output value reaches 999% of the steady value, and the time required to obtain the same output with step input6
, 9T (EO in Figure 4: input waveform E
(Response to ESS Nistep force t)).

From the above, if the time constant of the instrument under test is known, K and T1 of test input signal 4Ey can be determined. T
1 in advance and memorize it as a list.

(f) Effects According to the automatic industrial instrument testing device of the present invention, the test signal input to the instrument under test is set to a value KEi that is larger than the predetermined value Ei for a predetermined time T1 at the time of rising, and after the predetermined time T1 has elapsed. , is set as the predetermined value Ei for the test, so even if the instrument under test has a first-order lag time constant, the output waveform can be made to rise quickly, and the required measurements can be performed quickly. can.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of an input waveform when measuring the linearity of a conventional industrial meter, and FIG. 2 is a schematic diagram showing the connection state when using the industrial meter automatic test device according to the embodiment of the present invention. , FIG. 3 shows one embodiment of the present invention] A block diagram of an industrial instrument automatic testing device; FIG. 4 is a diagram showing a test input signal outputted from the motion testing device and its output response waveform; 5
The figure shows the control girometer 1 of the automatic test apparatus, and FIG. 6 is an input/output waveform diagram of the instrument under test for explaining the operation when testing the instrument under test using the automatic test apparatus. 11: Measuring section, 11CP [J, 15: Memory, 17: Signal generation section, 20: Setting section Patent applicant Shimadzu Corporation Representative Patent attorney Shin Naka Toshige Figure 1 Figure 2 Figure 5 and 6 figure

Claims (1)

[Claims] (1) A signal generation section that outputs a test signal for input to the instrument under test, a measurement section that receives the output signal of the instrument under test and performs test measurements, and supports different delay time constants of various instruments under test. Then, a value K larger than the predetermined test input signal Ei
waveform list storage means for storing in advance a waveform pattern including Ei and a time T for outputting the value; means for inputting a delay time constant of the instrument under test; and a means for deriving the corresponding KEi value and time T from the waveform list storage means in response, and outputs the KEi signal from the signal processing section for 7 hours from the start of measurement, and outputs the Ei signal after time T. An automatic test device for industrial instruments, characterized in that it generates a signal.