JPS5837519A - Electromagnetic flow meter - Google Patents

Abstract

PURPOSE:To reduce the number of hardwares and obtain reliable measured values by connecting an operation controlling part including a one-chip microcomputer to enable to execute a program for the measurement, operation, processing, etc. of flow rates. CONSTITUTION:A synchronous signal SYNC is supplied to an interrupting port INT of a one-chip microcomputer 141 incorporated in an operation controlling part 14 of a flow meter to start a measurement processing program for calculating the measured values of flow rates and writing these values in corresponding memories. In the operation processing program, the flow rate value and the pulse width conversion value of the flow rate, etc. are operated and written in the corresponding memory on the basis of the read measured value of flow rate and an output processing program is executed by an internal interruption to output the read operation value. During said period, a necessary calibration factor and the set value of constant can be written in a corresponding memory by a keyboard 151 through an additional I/O port 142, reducing the number of hardwares and finding reliable measured values.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetic flowmeter, and more particularly to an electromagnetic flowmeter that measures a flow rate using a control stage such as a microcomputer.

In the electromagnetic flowmeter of the prior art, C is for calculation processing, measurement control, and calibration method related to flow rate, etc.
Despite the use of complicated and enormous amounts of I\-ware, the obtained flow rate measurement values are not always reliable, and furthermore, the cost reduction is also poor.

An object of the present invention is to solve the above-mentioned technical problems, and to achieve reliable flow rate by processing the measurement and calculation of flow rate etc. in software, for example, through a one-chip microcomputer-containing calculation control unit. It is an object of the present invention to provide an electromagnetic flowmeter that can obtain measured values and is excellent in reducing cost.

FIG. 1 is an overall block circuit diagram of one embodiment of the present invention. The transmitter 1 includes a flow rate signal detection section 11, an excitation 'F flow rate signal detection section 12, an integral conversion section 13, an arithmetic control section 14, an operation display section 15, an analog transmission section 16, and a pulse width output section 1.
7, counting pulse output section 18, alarm output section 19, ■ reverse flow signal output section 20, and 6 Domei signal generation section 1 (including 10).The moving magnet 2 includes an excitation power supply rectification section 21, an excitation current signal rectification section 22, an excitation current control switch section 23, and an excitation current signal changeover switch section 24.

The detector 3 includes a conduit 31, field generation windings 32 and 33,
and signal detection electrodes 34 and 35.

The signal detection electrodes 34 and 35 of the detector 3 are connected to the preamplifier 111 of the flow signal detection section 11 in the transmitter 1 via the flow signal line 4. The excitation IE flow signal switching section 24 of the exciter 2 is connected to the preamplifier 121 of the excitation current signal detection section 12 in the C1 transmitter 1 via the excitation current signal line 5. The excitation IK source rectifier 21 of the exciter 2 is connected to the synchronous signal generator 100 of the C1 transmitter 1 via the synchronous signal line 6.

The excitation current control switch section 23 and the excitation current signal changeover switch section 24 of the exciter 2 are used for excitation' and E, respectively.
The excitation command signal (10NR) of the transmitter 1 is transmitted via the current control line 7 and the excitation current signal switching control line 8.

It is connected to each output terminal of (IONF) and each output terminal of excitation current signal switching control signals (CONF) and (CONR). In this way, the exciter 2 has an excitation 1F
The detector 3 is connected to the transmitter 1 via the flow signal line 5, the synchronization signal line 6, the excitation current control line 7, and the excitation current signal switching control line 8, and the detector 3 is connected to the °C1 transmission via the flow signal line 4. connected to device 1.

The transmitter 1 continuously operates according to the setting contents of the setting device 151 of the operation display section 15. The setting device 151 is composed of a digital switch or a keyboard, etc.・The exciter 2
The excitation power supply rectifier 21 consists of a commercial power supply 210, a power transformer 211, an exciting current detection current transformer 212, and a rectifier 213. The current is rectified by 'C and applied to the excitation current control switch section 23. Since the excitation current control switch section 28 of the exciter 2 is connected to the field generation windings 32 and 83 of the detector 3, the field generation windings 32 and 33 have 1. An excitation current (2) flows through the excitation current control switch section 23.

The detector 3 generates a signal corresponding to the flow rate of the fluid flowing inside the conduit 31 under the field generated by the field generating windings 32 and 33 at opposing electrodes 34 and 35, and also outputs the generated signal. The signal is sent to the flow rate signal detector 11 of the transmitter 1 via the flow rate signal line 4. In this way, the C1 transmitter 1 responds to the flow rate signals and excitation current signals sent from the exciter 2 and the detector 3, and transmits the flow rate value of the fluid flowing inside the conduit 31 of the C detector 3 as follows. Measures °C and performs arithmetic processing based on the program. Figure 2 shows
FIG. 3 is a waveform diagram for explaining the operation of the embodiment shown in the first figure. Hereinafter, the operation of the transmitter 1 will be explained by the calculation control section 14 inside it.
I will explain according to the program installed in 'C'.

(1) Measurement processing program From the power transformer 211 of the excitation power rectifier 21 of the exciter 2, the second
An alternating current signal (ACIN') as shown in Figure 1) is applied to the synchronization signal generator 100 of the transmitter l.

The alternating current signal (ACIN) is a signal whose half cycle changes in the positive and negative directions at every timing ti (where ti is a positive integer).When such an alternating current signal (ACIN) reaches a maximum value or a zero value ( Each time the synchronization signal generator 100 reaches a predetermined value such as zero (in this embodiment), the synchronization signal F'5YNC having a high level and short pulse width is generated as shown in FIG. 2 (2). ) is generated. This synchronization signal is input to the interrupt port INT of the non-chip microcomputer 141 in the arithmetic control unit 14 at timing t.When the synchronization signal (5YNC) is input to the non-chip microcomputer 141, The processing program starts running.

One-chip microcomputer 14 at timing t1
A high-level positive direction excitation command signal (IONF) as shown in FIG. 2 (5) is sent from the terminal 2 of the input/output port P+. This positive direction excitation command signal (IONF) is transmitted to the excitation current control switch section of the magnetometer 2 via one control line 71 of the excitation current control line 7 connected to the positive direction excitation command signal output terminal of the transmitter 1. 23 to the first and second switches SSR1 and SSR2. Then, these switches 5SRI and 5SR2 become conductive,
Due to this conduction, a positive excitation current I flows through the field generating windings 32 and 33 of the C1 detector 3 via the rectifier 218.

Under the field generated from the field generation windings 32 and 33 by the positive magnetodynamic current ■, the flow signal line 4 connected to the electrodes 34 and 35 oppositely arranged in the conduit 81 is connected to the conduit. A flow signal corresponding to the flow rate in 31 appears. This flow rate signal is input to the preamplifier 111 in the flow rate signal detection section ll of the transmitter 1, and the amplifier 111
At this point, the signal is amplified into a signal (e) as shown in FIG.

This flow rate signal (e) is detected in the next-stage comparator 118 by comparing the forward and reverse directions corresponding to the excitation direction, and is further transmitted from the next-stage photocoupler 114 as shown in FIG. 2 (141). , at timing 1, the flow rate signal is output as a signal for determining whether the flow rate signal is normal or inverse (POLI), which becomes the "C" high level.

This signal [POLI] is input to the terminal 0 of the port P5 of the additional input/output port 142 in the arithmetic control unit 14, and is transmitted from the terminal 8 of the same port P5 at the timing t2 as shown in FIG. 2 (4). It is output as an excitation current signal switching control signal (CONR) which becomes high level at .

In this way, the control signal (CONR) is
When the flow rate signal input to the terminal 1 corresponds to a positive excitation current, it is output from the terminal 3 of the port P5 of the additional input/output port 142. The control signal CC0NR) is also connected to the first and second excitation current signal changeover switch sections 24 through one control line 81 of the excitation current signal changeover control line 8 connected to the output terminal of the transmitter 1. The voltage is applied to switches ESI and ES2, which cause these switches ESI and ES2 to conduct.

Then, an excitation current signal having a phase opposite to the flow rate signal (e) flows from the excitation current signal rectifier 22 to the excitation current signal line 5 via the first and second switches ESI and ES2. As a result, from the output section of the preamplifier 121 of the excitation current signal detection section 12 of the transmitter l, as shown in FIG.
As shown in FIG. 1, an excitation current signal (i) having a reverse phase relationship with the flow rate signal is sent out. . , - In this way, the flow rate signal line 4 and the excitation current signal line 5
, the flow rate signal and the excitation current signal start flowing sequentially at timing h#'2. As the excitation current flowing through the field generation windings 32 and 83 increases toward the saturation value, the C1 flow rate signal (el
and excitation current signal (i), respectively, Fig. 2 01)
As shown in and OQ, the level increases. In this way, the period until the C1 excitation current reaches the saturation value,
The synchronization signal [5YNC] is sent from the synchronization signal generator 100 to the one-chip microcomputer 14 of the arithmetic control section 14.
The required number of times the input signal is input to the terminal INT of No. 1 is counted.

One-chip microcomputer 14 at timing t5
As shown in FIG. 2 (7), a high-level flow rate signal measurement command signal (: E
MF) is sent out, and at the same time, Fig. 2 (9)
As shown in 2, the measurement stop command signal [CNT], which was at a high level until just before timing t5, goes down to a low level. In this way, the photocoupler switch 112 of the flow rate signal detection section 11 conducts the high level flow by the signal measurement command signal (EMF), and also the integral conversion section 1
The No. 3 photocoupler switches 185 and 186 are cut off when the measurement stop command signal (CNT') becomes low level. In such a state, the flow rate signal (e) is input to the preamplifier 181 of the 'C integral converter 13 via the photocoupler switch 112 in a conductive state, and is then input to the preamplifier 181 of the C integral converter 13, and is then input to the preamplifier 181 of the C integral converter 13. The signal is converted into an integral signal (ec) by the converter 182 as shown in FIG. 2(2). ``The integral signal (ec) draws an integral curve with a downward slope at timings t to t8,'' and the level decreases.

The synchronization signal (SYNC) is at this timing t5 to t8.
During this period, the '7-chip microcomputer 141 counts the required number of times, and high-speed integration is performed within this computer.゛The result value Ne+ of high-speed integration is 1
It is stored in the memory Me of the non-chip microcomputer 141, etc. Next, in Thailand, mink t, flow rate signal measurement command signals (EMF) i, t,
becomes low level. As a result, the first cover switch 112 is cut off. At the same time, a high-level excitation current signal measurement command signal CCURR] is transmitted from the terminal 5 to the photocoupler switch 12 of the excitation current signal detection section 12.
2. This makes the photocoupler switch 122 conductive.

In this way, the photocoupler switch 112 and the
By changing the conduction/cutoff state of the integral converter 1
3, an excitation current signal is sent instead of the flow-eating signal.

The excitation current signal is input to the preamplifier 131 of the integral converter 13 in the same manner as described above, and then integrated by the integrating resistor 138, the integrating capacitor 137, and the integrator 132. By this integration, the excitation current signal [i] becomes
It is converted into an integral signal (ec) as shown on the α timing side 9 onwards in FIG. 2. The integral signal Cec:1 decreases in level IR from timing 5 to t8, but increases in level from timing 9 onwards.

The integral signal (ec) is also sent to the comparator 1 of the integral conversion unit 13.
After being input to 33, °C1 is input via photocoupler 134.
It is converted into a comparison output signal (CMP) as shown in FIG. 203. This signal (CMP) is input to the terminal O of the input/output port Pl of the one-chip microcomputer 141.

When the integral signal (ec) reaches a zero value in the middle of timing t12, the comparison output signal 1:l:CMP) is
Changes from low level to high level. This change is 1
It is detected in the two-chip microcomputer 141. In the one-chip microcomputer 141, the synchronization signal [5YNC] is counted the necessary number of times during the period from timing t to the middle of t1□, and during that period,
C high-speed integration is performed within the microcomputer 141. The result value Ni+ of the integration is stored in the memory Mitt of the computer 141.

The excitation current measurement command signal (CURR) is the signal “cMP”
Synchronizes with the timing when the signal changes from low level to high level, and changes from high level to low level. by this,
The photocoupler switch 122 is cut off [Fig. 2 (
8) and α]. At timing [13], the one-chip microcomputer 141 receives a high-level measurement stop command signal (C
NT) is sent. As a result, at timing [13] photocoupler switch 112 > 3 J: 0' 12
2 is cut off, photocoupler switches 135 and 13
6 is made conductive. In such a conduction/cutoff state of each switch, the memory Mkf (stored in advance) of the one-chip microcomputer 141 is stored in the preset calibration coefficient value, and the memory Mkf is stored as described above.
, the integrated values Ne+ and N1 stored in Mi etc.
The computer 141 calculates the flow rate measurement value V+ given by the following formula (1) using + and the calculation result is stored in the memory MV.
+, /Ne+ -fl) In this way, the measurement processing cycle during positive direction excitation of 'C1 is completed.

Next, a measurement processing cycle during negative direction excitation will be explained.

At timing [13, a synchronization signal (SYNCI) is input to the one-chip microcomputer 141.
j-71, the positive direction excitation command signal (IONF) and the excitation 'IE flow signal switching control signal (CONR:) from terminal 2 of its input/output port P+ and terminal 8 of port 5 of the additional input/output port 142 are high. level to low level. As a result, the first and second switches 5SRI and 5SR of the excitation CF flow control switch section 23 of the exciter 2
2 is cut off, and at the same time, the first and second switches ESI and ES2 of the excitation current signal changeover switch section 24 are also cut off. Synchronization signal r'5Y at timing t14
NC) is input to the terminal INT of the input/output port P of the one-chip microcomputer 141. Then, a high level negative direction excitation command signal [10NR] is sent from the terminal 3, as shown in FIG. 2 (6). This command signal (I ONR) is transmitted to transmitter 1.
output terminal and the other control line 72 of the excitation current control line 7
The excitation current is applied to the third and fourth switches 5SR8 and 5SR4 of the switch section 23 through the excitation current control switch.

This will cause these switches 5SR3 and 5S
R4 is made conductive. By doing so, excitation currents in opposite directions flow through the C1 field generating windings 32 and 33. In this way, through the flow rate signal line 4 connected to the counter electrodes 84 and 35 in the conduit 31 of the detector 3, the flow rate signal detecting section 11 of the transmitter 1 is supplied with reverse excitation ``a flow rate corresponding to the flow E''. A signal is applied.

When the C1 meteor signal is applied in this way, the photocoupler 114 of the flow rate signal detection section 11 sends a signal to the terminal 0 of the port P5 in the additional input/output port 142 of the arithmetic control section 14 as shown in FIG. 2 al. A low level determination signal +3jpotD is input. The determination of whether the flow rate signal is positive or negative is performed within the additional input/output port 142 by inputting the determination signal 2. In this way, the flow rate is Excitation current signal switching control signal (CO
NF':] is sent.

This control signal [C0NF] is transmitted to the switch section 2 via the other control line 82 of the excitation "[E flow signal switching control line 8".
4 to the third and fourth switches ES8 and ES4. In this way, these switches ES8 and ES4 are rendered conductive. As a result, the reverse phase of the excitation current signal with respect to the flow rate signal is selected.

After c1 timing tx4, the level of the flow rate signal ['e] decreases as shown in Figure 2 0η, while the level of the excitation current signal decreases as shown in Figure 2 01.
The temperature increases as shown in °C. With respect to such level changes of the flow rate signal and the excitation current signal, in the same manner as described above, the L"r integral value Ne-
However, an integral value Ni- is obtained in the middle of timings t22 to t26, and each integral value is stored in memories Me, Mi, etc.

As a result, the calculation for obtaining the flow rate measurement value V- given by the following equation (2) is performed in the same manner as in the above equation (1).

V--K -Ni-/Ne--(2) In this way, the flow rate measurement value V- is calculated in the calculation control unit 14, and stored in the memory Mvrt along with the positive and negative signs of the flow rate. The measurement processing cycle performed during excitation ends.

In each measurement processing cycle described above, the flow rate signal detection unit 1
The flow rate signal output from the preamplifier 111 of No. 1, the excitation current signal output from the preamplifier 121 of the excitation current signal detection section 12, and the signal output of the photocoupler 134 are as follows.
01), al, @, and C1 as shown in FIG. 2, respectively.

The flow rate measurement stop command signal (CNT) is an excitation current measurement command signal (CURR) or a flow rate signal measurement command signal (EMF).
) is at a low level, photocoupler switches 185 and 186 are made conductive as a calibration command signal to integrate zero voltage 'C, and the preamplifier 181, integrator 182, and comparator 188 in the integral converter 18 are This is a signal for causing the capacitor 189 to hold the offset and drift as an error voltage. This signal causes the integrator 13
The integral output signal (ec) of 2 can be held at zero voltage, so that highly accurate integration is performed in the integral converter 18.

In addition, the effects of external magnetic fields and the polarity effects of the detection electrodes 84 and 85, which include circuits for flow rate measurement, etc., are removed.
1. When it is necessary to improve the accuracy of flow rate measurement, the flow rate measurement value ■ can be calculated using the following formula (3), although the speed of flow rate measurement is halved.
and store the result in memory MV1. It is best to store it in the throat.

■−−(v+ + ■2) ・・・(
3) Note that each integrated value Ni+, Ne+, Ni-1 mentioned above
When either Ne- overflows, an overflow signal is sent out, and when this overflow signal is received, an alarm signal is issued.
Notify of abnormality.

(11) Arithmetic processing program This program is used to calculate the flow rate measurement value V after the above-mentioned measurement processing program is completed, and to
Executed immediately after being stored in, etc.

The flow rate measurement value V of the formula (3) stored in advance in the memory of the one-chip microcomputer 141,
The preset coefficient C and the preset constant F stored in each corresponding memory are retrieved and the following equation (4) or (5
) Calculate the flow rate value Q given by

Q=C-V-F...(4)
Q=C(V-F)...(5
) Here, C is the flow velocity coefficient, and F is the false flow rate value when the mixed fluid is stationary for a long time.

Next, the pulse width conversion value PQ of the flow rate given by the following equation (6) is calculated using the meteor value Q calculated based on the above equation (4) or (5), and the calculated value is stored in the memory. M(
It will be stored in detail.

■) (each = Kp-Q
...(6) Here, Kp is the pulse width conversion coefficient of the flow rate.Furthermore, using the flow rate value Q calculated based on the above formula (4) or (5), the following formula (7) is calculated. The converted value HQ of the number of pulses per unit time for the given flow rate is calculated, and the calculated value is stored in the memory M■.

-tIQ=Ko/Q (tago, when Q=O, Ht
)=O)...(7) Here, Kll is a conversion coefficient of the number of pulses per unit time of the flow rate.

Furthermore, the analog conversion value AQ of the flow rate given by the linear equation (8) is calculated using the meteor value Q calculated based on the above equation (4) or (5), and the calculated value is stored in the memory MA. Stored in

AQ=KA-Q...(
8) Here, KA is the analog conversion coefficient of flow rate.

In this way, in the arithmetic processing program, the flow rate value Q, the pulse width conversion value PQ of the flow rate, the converted value HQ of the number of pulses per unit time of the flow rate, and the analog conversion value AQ of the flow rate are calculated. Stored in the corresponding memory. Even while this arithmetic processing program is being executed, the above-mentioned measurement processing program and the later-described output processing program are given priority over the arithmetic processing program.

Although the measured values obtained in this way are obtained as fixed-point binary values, when considering points such as shortening calculation time and ease of processing, it is necessary to calculate using floating point method. It's better to do. This floating point method has the advantage of easy software processing. However, when using a one-chip microcomputer or the like as a CPU (abbreviation for central processing unit), (1) the circuit density of LSI (abbreviation for large-scale integrated circuit) at the current technology level is low; (2) There is a lack of ROM area for external input/output control, and (2) arithmetic processing overhead and rJ'' are required as a C1 transmitter. Problems such as a decrease in efficiency arise.In order to solve this problem, for example, a one-chip microcomputer dedicated to calculations can be used to operate a floating point processor IC, etc. to perform C processing. It is best to use ``C1 calculation and processing as 5
``Simultaneous processing is now possible, which solves the problems of υC-) and (2) above.

(iii) Output processing program This program is a one-chip microcomputer 1
-) °C execution is started by an internal interrupt by the built-in timer of 41. (a) The basic clock or external reference clock of a one-chip microcomputer is divided directly or by a counter within the microcomputer and is used as a timer interrupt input. (b) The flow rate value Q is taken out from the memo IJktQ of the one-chip microcomputer 141 every timer interrupt or every integer multiple of timer interrupt 1).

From the output port of the additional input/output boat 142 to the operation display section 1
The flow rate value Q is displayed on a display 152 made of, for example, an LED (light emitting diode) inside the flow rate. (C) Every timer interrupt or every integer multiple of the timer interrupt, the arithmetic processing completion flag is checked, and the analog converted value AQ of the flow rate is retrieved from the memory MA of the one-chip microcomputer 141. When Aq-0, the arithmetic processing completion flag is reset and subsequent output processing is stopped. When AQ≠0, from the terminal 6 of the input/output port P of the one-chip microcomputer 141,
As shown at timing t13 of η, the high level
A flow rate analog conversion command signal (PWDA) is sent out.This makes the photocoupler switch 165 of the analog transmission output section 16 conductive.On the other hand, from the terminal 3 of the port P4 of the additional input/output port 142, the signal shown in FIG. As shown in timing [13] of M, the signal (INTDIS) changes from high level to low level.This causes the photocoupler switch 166 of the C1 analog transmission output section 16 to be cut off. Each time the timer interrupts, 1 is sequentially subtracted from the analog conversion value AQ of the flow rate.

In this way, when the analog conversion value AQ reaches the value of zero,
The conversion command signal (PWDA) changes from high level to low level and transmission is stopped [in the middle of timing t16 in Figure 2 αη] By stopping the transmission of this signal (PWI) A':l, the photocoupler switch f 165 is blocked. At a timing slightly shifted from the timing at which the transmission of this signal -PWDA:) is stopped, a high level sampling hold signal (SHPLS) is output from terminal 2 of port P4 of the additional input/output port 142 as shown in FIG. The photocoupler switch 167 of the analog transmission section 16 is made conductive by this high level signal (SHPLS:) of -6 which is sent for a certain period of time (from the middle of timing t16 to the middle of t17). Utilizing the period of conduction, the integrated output of the integrator 162 is applied to the capacitor 72 via the photocoupler switch 167 to provide an analog transmission voltage V.

[See Q0 in FIG. 2] and the C sample is held.

Then, when this high level signal (SHPLS) becomes low level in the middle of timing t17, the no 1 level signal [INTDNS] is connected to the ζ port of the additional input/output port 5142 as shown in FIG. It is sent from the P4 terminal. This high-level signal (INTDIS:) turns on the photocoupler switch 166 of the analog transmission output section 16, and the analog transmission output cycle ends.

The analog transmission voltage vO sampled and held in the capacitor 1612 of the analog transmission output section 16 is
The standard transmission current I is converted to voltage-to-current (V-I) in output amplifier 168 as shown in FIG.

It is output from the output amplifier 168 as . Note that, corresponding to the sign of the flow rate value Q, a signal (POLO) as shown in FIG.

This signal (POLO) is sent to the photocoupler 201. The relay 208 is driven via the output amplifier 202, and the forward/reverse flow rate signal POL is sent out from the relay contact MC4. (d) Signal (4prnxs
) is high level and the port P4 of the additional input/output port 142
During the period when the signal is being sent from the terminal 8, the photocoupler switch 166 of the analog transmission output section 16 is turned on, and the other photocoupler switches 165 and 167 are cut off. In the conduction cut-off state of each switch 1 (i6, 165 and 167), the integral output (e
W)' (see FIG. 2 (1)) is suppressed, and therefore the comparison amount set value of the setter 168 for the comparator 164 can be maintained at a predetermined value.

(e) The converted value HQ of the number of pulses per unit time of the flow rate is retrieved from the memory Ma of the one-chip microcomputer 141 by the timer interrupt. When HQ=0', subsequent output processing is stopped. ) If IQ≠0,
From the terminal 1 of the port P4 of the additional input/output port 142 in the arithmetic control section 14, a high level signal [PPH] as shown in FIG. 2 01 is sent out. Then, 1 is subtracted from the pulse number conversion value HQ every time the timer interrupt occurs, and when the value HQ is halved, the transmission of the signal (PPH) is stopped. As the transmission of this signal (PPH) is stopped, the relay 188 and the counter 184 are
is driven, and the number of pulses of the signal [PPH:] per unit time, that is, the integrated value of the flow rate is displayed continuously at the relay contact MCI. Note that a timer interrupt is performed until the value HQ becomes zero, and the number of pulses of the flow rate Q per unit time is output.

(f) The pulse width conversion value PQ of the flow rate is retrieved from the memory Mp of the one-chip microcomputer 141 by the timer interrupt. When PQ=O, subsequent output processing is stopped. At PQ¥0, a high-level pulse width command signal (PWDC) shown in FIG. 2 αQ is sent from the terminal 7 of the input/output port P1.

When this signal (PWDC) is sent out, the pulse width conversion value PQ bh et al. ) is stopped from being transmitted and becomes low level. When the transmission of the signal (PWDC) is stopped, the relay 178 is driven via the photocoupler 171 of the pulse width output section 17 and the output amplifier 172, and the signal (PWD) is continuously transmitted via the relay contact MC2. Output.

At this time, an operation of subtracting 1 from the specified pulse width p Q M for each timer interrupt is performed in parallel to define a pulse width conversion cycle. Furthermore, if the result is abnormal or overflows during arithmetic processing, a signal to that effect (OVF
) is sent. Further, when the one-chip microcomputer 141 becomes inoperable and the signal CALE) is generated, the alarm logic section 1911 in the alarm output section 19
A C relay 194 is driven by a photocoupler 192 and an output amplifier 193, and a C1 alarm output (ALARM) is generated.
is sent.

θ■) Setting value processing program This program is started to be executed by a keyboard interrupt performed based on a key operation on the keyboard 151 on the operation display section 15. That is, the generated signal based on the key operation of the keyboard is input as an interrupt input, and the calibration coefficient value required for execution of the measurement processing program etc. and the flow velocity coefficient C1 required for execution of the calculation processing program etc.
False flow rate value F1 during long-term static ratio of mixed fluid Pulse width conversion coefficient Kp.

The converted value HQ of the number of pulses per unit time of the flow rate is stored in each corresponding memory such as a one-chip microcomputer through the input port of the additional output port 142.

The contents stored in each corresponding memory are output and displayed on the display 152 of the operation display section 15 via the output port of the additional input/output port 142 in the calculation control section 14. Further, the flow rate value being measured is also stored in the memory of the one-chip microcomputer 141 or the like when necessary. In this way, the corrected flow rate value is inputted to the flow rate value stored in each corresponding memory of the one-chip microcomputer, etc., and the stored content values such as the calibration coefficient value and each constant are also automatically corrected. Accordingly, the straight pipe diameter of the conduit 81 is also corrected. In this way, the contents stored in each memory are output and displayed via a display 152 such as an LED.

A reset signal (R5ET) is generated via the reset switch 153 in the operation display section 15 and the reset pulse generation W 146 in the arithmetic control section 14, and the reset terminal RES of the one-chip microcomputer 141 is generated.
Input the reset signal (R5ET) to ET. Then, each of the programs described above will be reset.

In addition, this reset signal (R5ET) is transmitted to the alarm output section 1.
It is also input to the alarm logic section 191 at g, and the C1 alarm output state is reset.

As described above, according to the present invention, a one-chip microcomputer or the like is used to perform arithmetic processing and control for flow rate measurement, so that the following unique effects are achieved.

(1) Since control is performed by software processing, a special control circuit is not required, and therefore cost can be reduced and reliability improved.

(2) Since the flow rate value can be obtained by calculation, it is not particularly necessary to give constant current characteristics to the excitation current, and therefore the same effect as in (1) above is achieved.

(3) The above-mentioned constants and coefficients necessary for arithmetic processing can be easily input and changed by keypad interrupt, so it can be carried out to correspond to various types of detectors, and it can be carried out in response to a variety of outputs. Because it is possible to
Very convenient to use.

(4) Calibration of the instantaneous value of the °C1 flow rate can be easily performed by operating the keyboard or the like.

(5) Calibration and inspection programs for each circuit can be executed and performance can be confirmed by keyboard operations, which greatly facilitates maintenance and inspection work.

(6) In addition, processing capabilities such as flow rate value determination and flow rate control may be added.

[Brief explanation of the drawing]

FIG. 1 is an overall block circuit diagram of an embodiment of the present invention;
FIG. 2 is a waveform diagram for explaining the operation of the embodiment shown in the first diagram. 1... Transmitter, 2... Exciter, 3... Detector, 4
...-Flow rate signal line, 5... Exciting current signal line, 6...
Synchronous signal line, 7... Exciting current control line, 8... Exciting current signal switching control line, 11... Flow rate signal detection section, 1
2... Excitation current beam detection section, 13... Integral conversion section,
14... Arithmetic control section, 15... Operation display section, 16.
...Analog transmission output section, 17...7X6, Res width output section, 18...Counting pulse output section, 19...Alarm output section, 20...Forward/reverse flow rate output section, 21...Excitation Power supply rectifier, 22... Exciting current signal rectifier, 23...
Excitation current control switch section, 24... Excitation-E original signal changeover switch section, 31... Conduit, 32, 33...
Field generation winding, 84, 85...Flow rate signal detection electrode,
100...Synchronization signal generator agent Patent attorney Oka 1
) Kazuhide

Claims (1)

[Claims] A measurement processing program that is started by an external interrupt signal, calculates a flow rate measurement value, and stores the calculated flow rate measurement value in a first memory; A calculation process in which the measured flow rate value stored in the first memory is retrieved, the flow rate value, the pulse width conversion value of the flow rate, etc. are calculated based on the retrieved flow rate measured value, and this calculated value is stored in the second memory. A program, an output processing program that is started by a timer interrupt, retrieves the calculated value stored in the second memory, and outputs the retrieved calculated value, and an output processing program that is started by an interrupt signal from a keyboard, etc. and is necessary for the program. A setting value processing program for storing coefficients and constants such as calibration coefficients in an eighth memory is executed by a measurement control means such as a microcomputer.
Electromagnetic flowmeter.