JPS6197578A - Measuring pulse processor - Google Patents

Abstract

PURPOSE:To obtain a highly accurate processor with limited measuring errors which enables the detection of fine variations without changing the sampling cycle, by calculating a digital measured value per unit time using highly precise time pulse. CONSTITUTION:A pulse generated from a measuring device 1 activates a measuring pulse counter 3 to perform an incremental counting through an input unit 2. On the other hand, a normal time pulse generated from a time counting module 4 activates a time pulse counter 5 to perform an incremental counting while a highly accurate time pulse does a highly accurate time pulse counter 12 to perform an incremental counting. A comparative decision means 16 determines whether calculation using a highly precise pulse counts should be done or not, by using a pulse counts restriction value for selection of a desired pulse calculation method selection previously memorized in a memory 15 depending on pulse counts generated per one sampling required generated from the measuring device 1. Then, the results of calculation based on the resulting counts are multiplied by a conversion constant for E.U. value expression by an E.U. value conversion means 10 to update the data base 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a measurement pulse processing device suitable for calculating a digital measurement value per unit time using measurement pulses and time pulses.

[Technical Background of the Invention] The configuration of a conventional measurement pulse processing device is shown in FIG. Measured quantities of the plant, such as flow rate and velocity, are converted from the measuring device 1 into pulse signals and transmitted to the pulse input device 2 . There, it is converted into a digital signal, and the digital signal is integrated by a measurement pulse counter 3 that can store it.

On the other hand, the time measurement module 4 is constituted by a crystal oscillator or the like, and accurately generates time pulses at preset time intervals, and updates the value of the time pulse counter 5 from which the time pulses are accumulated.

The sampling management device 6 normally performs sample management by sending the contents of the measurement pulse counter 3 and the time pulse counter 5 to the pulse count calculation means 7 at regular intervals. At the time of sampling, the pulse count calculation means 7 reads the digitally converted measurement data from the measurement pulse counter 3, and at the same time reads the time data from the time pulse counter 5, and converts the measurement data and time data read during the previous sampling into the previous value. By reading from the storage device 8 and subtracting the previous value from the current value,
A pulse count value related to the measured amount and time between the previous sampling time and the current sampling time (one sampling unit) is calculated.

The measured quantity in one sampling unit obtained by the pulse count calculating means 7 is divided by the time correction means 9 using the time in one sampling unit also obtained by the pulse count calculating means 7, so that the measured quantity is is converted into a time-based quantity (/H). Furthermore, E, U, (Engin
It is converted into engineering units by the value conversion means 10, and updated and stored in the database 11 as a digital measurement value P per unit time.

That is, the arithmetic processing performed by the time correction means 9, E, U, and value conversion means 10 can be expressed as the following equation (1).

P=-mu:ヱ”XK ・・・・・・・・・・・・・・・
...(1) pto-ptl Where, P: Desired pulse E, U, value (digital measurement value per unit time) Po: Current pulse counter value Pl: Previous pulse counter value pt, : Current time pulse counter value pt uni Previous time pulse counter value, P: E, U, value conversion constant [Problems in the Background Art Normally, the pulse of the time measurement module 4 is generated every few m5ec. Here, for example, if we take the time correction of the steam turbine rotation speed of a thermal power plant as an example, the timing module 4
generates pulses at intervals of 5m5ec. The turbine rotation speed is measured using a pulse detector that generates 1,000 pulses per revolution.

Therefore, if the rated rotational speed of the steam turbine is 300 rpm, K = 3000 from the above equation (1).

In this state, if the sampling period by the sampling management device 6 is 5 seconds, the count value of the turbine rotation speed for 5 seconds is 3000 x 4 x 5/60 = 100
The count is 0. On the other hand, the count value for 5 seconds of the 1-time pulse is 510.005 = 1000 counts.

Therefore, when the turbine rotational speed measurement value P is calculated according to the above equation (1) based on these measurement data and time data obtained in 5 seconds, it becomes as follows.

On the other hand, due to fluctuations in the sampling period of the sampling management device 6, the turbine rotation speed measurement value P2 when one count of time pulses cannot be picked up compared to when the time data input to the pulse count calculation means 7 is normal is determined by the above-mentioned formula (1). Therefore, P2='-''-X3000#3003 (rpm).

As is clear from the above, even if the time data (time count value) input to the pulse count calculating means 7 deviates by just one count due to fluctuations in the sampling period,
, -p□=3 rotations of error will occur.

In order to reduce this error, the sampling period can be made longer, but if this is done, fine fluctuations in the measured quantity cannot be detected. Furthermore, it is possible to change the pulse generation rate without changing the sampling period, but this has economical hardware constraints, such as an increase in the number of counts and the need for a counter with a large number of digits.

[Object of the Invention] An object of the present invention is to provide a high-precision measurement pulse processing device with a simple configuration that can detect small fluctuations without changing the sampling period and with less measurement error.

[Summary of the Invention] For this reason, the present invention extracts a more precise pulse from the timing module and also uses this currant value as time data, thereby reducing the measurement error per time count value due to fluctuations in the sampling period. It is characterized by

[Embodiment of the Invention] Figure 1 shows an embodiment of the present invention.
The same reference numerals as in the figures indicate the same or corresponding parts.

The configuration of the figure is different from that of FIG. 3 in that a timing module 4 generates high-precision pulses, a high-precision time pulse counter 12 counts these pulses, and a high-precision time pulse counter 12 is provided for each sampling period determined by a sampling control device 6. A high-accuracy method that reads a pulse count value from the pulse counter 12 and calculates a high-precision pulse count value between samplings using the pulse count value of the high-precision time pulse previous value storage device 14 that stores the pulse count value at the previous sampling time. A pulse count calculation means 13 is added, and a storage device 15 is further provided for storing arbitrary pulse count limit values for determining pulse calculation method selection for all pulse inputs, and a pulse count calculation means for calculating pulse counts from the plant. Comparing the pulse count from the calculation means 7 and the count limit value retrieved from the storage device 15,
Comparison/judgment means for selecting a calculation using a conventional time pulse count value from the time pulse counter 5 and a calculation using a combination of the time pulse count value and a high precision time pulse count value obtained from the high precision time pulse counter 12 16 and a high-precision time correction means 17 that performs calculations taking into account a high-precision time pulse count value.

The high-precision time pulse is 1
Pulses with a generation frequency of 0 times or more are accumulated in the high-precision time pulse counter 12 between one time pulse and are cleared to 0 every time a time pulse occurs, until the next time pulse is generated. Do the total.

Any pulse count limit value stored in the storage device 15 can be determined by pulse calculation processing using the count value of the high-precision time pulse counter 12, or by not using the count of the high-precision time pulse counter 12 as in the past. This is for selecting whether to calculate or not, and a value at the same level as the time pulse count number is set.

Next, the operation of the measurement pulse processing device configured as described above will be explained with reference to the time chart of FIG.

Pulses generated by the measuring device 1 count up a measuring pulse counter 3 through a pulse input device 2. on the other hand,
A normal time pulse generated by the time measurement module 4 causes a time pulse counter 5 to count up, and a high precision time pulse causes a high precision time pulse counter 12 to count up.

The bit lengths of the measurement pulse counter 3 and time pulse counter 5 are determined in advance, and when the count value becomes full, the counters are cleared to O and the update process continues. As a result, the difference in count value from the previous sampling time is always determined.

The high-precision time pulse counter 12 is cleared to 0 when the generated pulse updates the time pulse counter 5 by the time measurement module 4, and continues to count up.

In Fig. 2, Tt indicates the current sampling, and Tt
t-1 indicates the previous sampling time.

P is the count value of the measurement pulse counter 3 that updates the pulse from the measuring device 1, pt is the count value of the time pulse counter 5 that updates the pulse from the timing module 4, and C2 is the count of the high precision time pulse counter 12. Indicates the read value.

In addition, P is the count number at the previous sampling time Tt-1 of the measurement pulse counter 3 that updates the pulse from the measuring device 1, and Pt1 is the count number of the time pulse counter 5 that updates the pulse from the timing module 4. The count number at the previous sampling time point Tt- is taken out from the previous value storage bag g8. C1 is a high precision time pulse counter 12
The count number at the previous sampling point Tt-, is taken out from the high-precision time pulse previous value storage device 14.

Here, the difference between the number of pulse counts generated by the measuring device 1, the number of pulse counts generated by the timing module 4, and the number of counts of the high-precision time pulse counter 12 per sampling (Tt - Tt-1) is (po-
p□), (Pt, -Pt engineering), (cz -ct).

The comparison/judgment means 16 calculates the number of pulse counts (P) generated by the measuring device 1 per one sampling.

pi), it is selected whether or not to perform calculation using a high-precision pulse count number, using a pulse count limit value for selecting an arbitrary pulse calculation method previously stored in the storage device 15. That is, if the determined number of pulse counts (P, -P) generated by the measuring device 1 per sampling is less than the pulse count limit value stored in the storage device 15, the conventional calculation is performed, On the other hand, when the number is large, calculation is performed using the count value (cz-cl) per sampling of the high-precision time pulse counter 12.

The calculation result based on this count value is multiplied by E, U, a conversion constant K for expressing the value in the value conversion means 10, and the database 11 is updated.

The above-mentioned high precision time correction means 17, E, U, value conversion means 10
The calculation formula using the count value of the high-precision time pulse counter 12 is as follows.

P: Desired pulse EJ, value (digital measurement value per unit time) Po: Current pulse counter value P□: Previous pulse counter value pto: Current time pulse counter value pt, : Previous time pulse counter Value of C: Number of counts per 1 count of time measurement module time pulse C1: Value of previous high-precision time pulse counter C2: Value of current high-precision time pulse counter K: E, U, value conversion constants, that is, Fig. 2 As is clear from (d) and (e),
The high-precision time pulse count value between Tt and Tt- is
Since one time pulse count corresponds to a high precision time pulse C count, first, when the time pulse count value (pto-piyu) shown in FIG. 2(d) is converted to a high precision time pulse count value, (Pt , -Pt1) x C
becomes.

Next, since the fraction is (C2ct) from FIG. 2(e), the denominator of the right side of the above (2) can be obtained. Next, Tt −
The measured pulse count value (P, -P) between Tt-2 is
E, U.

When the value conversion constant K is set to be the same as in the above equation (1), it is necessary to multiply by 0, so that the numerator on the right side of the above equation (2) is obtained. In this way, by calculating the digital measurement value P per unit time using high-precision time pulses that are finer than the conventional time pulse interval, measurement values with little error can be obtained even if the sampling period varies slightly. That is, similar to the conventional example of measuring the turbine rotation speed, the sampling time is 5 seconds and the period of one time pulse is 511Is.
, the rated value of the turbine rotation speed is 300 Orpm, and the count value C of high-precision time pulses corresponds to 1 count of time pulses.
When P is set to 10, the turbine rotational speed measurement value P3 when there is no missed pulse is as follows.

On the other hand, the turbine rotation speed measurement value P4 when one high-precision time pulse cannot be picked up due to fluctuations in the sampling period of the sampling management device 6 is as follows.

P4= Snow book heat:,, X3000#3000.3(r
pm), and the error is P, -P, = 0.3 rotations.

In this way, if the digital measurement value P per unit time is calculated using the highly accurate time pulse count value of 1/10 period of one time pulse, the error per pulse is 1/1 of the conventional one.
It can be reduced to about 0.

Further, since the high-precision time pulse counter 12 used at this time only needs to have a capacity sufficient to count C, it can be constructed at low cost.

[Effects of the Invention] As described above, according to the present invention, a digital measurement value per unit time is calculated using a high-precision time pulse, so it is possible to reduce errors even if the sampling period is shortened. A highly accurate measurement pulse processing device capable of detecting even minute fluctuations in measured values can be obtained.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a measurement pulse processing device showing an embodiment of the present invention, and Figures 2 (a) to (e) are digital measurement values per unit time using the high-precision time pulses in Figure 1. FIG. 3, which is a diagram explaining the calculation method, is a block configuration diagram of a conventional measurement pulse processing device. DESCRIPTION OF SYMBOLS 1... Measuring instrument, 2... Pulse input device, 3... Measurement pulse counter, 4... Time measurement module, 5... Time pulse counter, 6... Sampling management device, 7
...Pulse count calculation means, 8. Previous value storage device, 9. Time correction means, lO..E, U, value conversion means, 11. Database, 12. High precision time. Pulse counter, 13... High precision pulse count calculation means, 14... High precision time pulse previous value storage device, 1
5... Storage device, 16... Comparison/judgment means, 17...
・High precision time correction means. Agent Patent Attorney Crest 1) -1 “Beano’ Figure 1 1, 6 Figure 2 Figure 3, 6

Claims (1)

[Claims] A measurement pulse counter that integrates measurement pulses, a time pulse counter that integrates time pulses, a sampling management device that samples the count values of both these counters at a constant cycle, and a previous value and a current value of the two sampled count values. A measurement pulse processing device comprising: a first calculation means for calculating a count value per sampling from , and calculating a digital measurement value per unit time from the count value per sampling; a high-precision time pulse counter that integrates the high-precision time pulse; a count value obtained by sampling the count value of the high-precision time pulse counter by the sampling management device; and a count value of the measurement pulse counter. a second calculating means that calculates a count value per sampling from the previous value and the current value of the count value obtained by sampling the value, and calculates a digital measurement value per unit time based on this; A measurement pulse processing device characterized by comprising means for selecting which of the first calculation means and the second calculation means to use.