JP2019060885A - Vibratory flow meter and method of generating digital frequency outputs - Google Patents

Abstract

To improve a device and method of generating digital serial frequency outputs in a Coriolis flow meter.SOLUTION: The present invention provides the theoretically lowest jitter for a given input clock, the highest possible pulse count accuracy, the highest possible absolute accuracy, easily implementable other aspects (including quadrature, pulse width, etc.) without requiring no specialized external hardware, and is, therefore, constructed (implemented) with commonly available serial output hardware used in most microcontrollers.SELECTED DRAWING: Figure 4

Description

  The present invention relates to devices and methods for generating digital serial frequency outputs, and in particular to generating serial digital frequency outputs to indicate flow rates in a Coriolis flow meter. .

  Traditionally, purely mechanical devices have generated frequency output from basic spinning wheels that are adapted to activate the switch after each revolution. This type of output is established and today is widely needed in various industrial applications.

  Frequency output (FO) is the digital output from a device that generates frequency by toggling a single line. In the industrial field of measuring flow, the frequency is usually proportional to the desired variable, eg mass flow. Coriolis mass flowmeters are described in detail as flow measurement techniques.

As disclosed in U.S. Pat. No. 4,491,025 and Reissued Patent No. Re 31,450, Coriolis mass flowmeters are configured to measure mass flow and other information about the material flowing through the pipeline. Typically, these flow meters comprise the flow meter electronics part and the flow meter sensor part. The flow meter sensor comprises one or more flow tubes having a linear or curvilinear structure. Each flow tube structure has a set of natural vibration modes that can be simple bending type, torsion type, radial type or combination type. Each conduit can be driven to resonate and vibrate in one of these natural vibration modes. The natural vibration mode of the vibrating system in which the substance is filled is partly defined by the sum of the mass of the flow tube and the mass of the substance flowing in the flow tube. When no matter is flowing through the Coriolis flowmeter sensor, all the parts along the flow tube vibrate in substantially the same phase. As material flows through the flow tube, Coriolis acceleration causes the sites along the flow tube to have different phases. The phase on the inlet side of the flow meter sensor lags the phase of the driver, and the phase on the outlet side of the flow meter sensor leads the phase of the driver.

  In general, Coriolis flowmeter sensors are provided with two pickoffs to generate sinusoidal signals at various locations along the flowtube that represent the motion of the flowtube. The phase difference of the sinusoidal signal received from the pickoff is to be calculated by the flow meter electronics. The phase difference between the two pickoff signals is proportional to the mass flow rate of material flowing through the flow meter sensor. An example of a Coriolis flowmeter is shown in FIG.

The flow meter electronics are adapted to receive the pick off signal from the pick off and process the pick off signal to calculate the mass flow, density or other characteristics of the material passing through the flow meter sensor.
Microcontrollers implemented in integrated circuits with multiple complex peripherals are commonly used in all flow meters. While widely available microcontrollers are commercially available and inexpensive, they are not specifically designed for flow meters. An example of a microcontroller is shown in FIG.

Low (less) "jitter" is important for measurement of instantaneous flow. Jitter is defined as relating to the accuracy of the period of any given pulse. For example, if the odd number of pulses is 99.9 Hz and the even number of pulses is 100.1 Hz, the average frequency will be 100 Hz, but the output will be expressed as having a jitter of 0.1 / 100 or 0.1%. Be done.
High accuracy (in terms of resolution) is important for the measurement of the total integrated flow. For example, if one pulse equals 1 g, then if 998 pulses are formed and the device indicates 1000 g, then the output is said to have an accuracy of 998/1000 or 0.2%.

  With regard to the other features of frequency output, one frequency output advances the other frequency output by 90 ° in the case of positive flow, and in the case of negative flow it is referred to as the dual frequency output delayed by 90 ° (general There is a class called quadrature). Another feature relates to non-50% duty cycle requirements. The frequency output must function over a wide range, typically between 0.001 Hz and 10000 Hz, but in some cases higher or lower frequencies may be required.

  As mentioned above, one way to generate the frequency output is to use various types of "multipurpose" digital hardware timer circuits, which can generally be used in microcontrollers. In this approach, a hardware timer (typically with divide by n and interrupt capabilities) is programmed to output a particular frequency for a certain amount of time. However, there are several disadvantages with this approach. Because the resulting frequency is from the divide by n algorithm, significant jitter will occur even with high frequency input clocks. For example, if the input clock is 10 MHz and the desired output is 9999 Hz, the timer must be switched alternately between 10000 Hz (division by 1000) and 9990.01 Hz (division by 1001). In addition, it is also difficult to create an algorithm that can accurately track the number of pulses output. The reason is that phase alignment of the output of the hardware timer does not occur simultaneously with the update time of the timer counter. The third drawback is that eight decades are required, as the multipurpose timer has only a maximum of 32 bits and can only provide a range of about 5 decades. Therefore, different input clocks and crossover thresholds must be introduced. This results in discontinuities which increase jitter below this threshold and make the maintenance of pulse accuracy more complicated. Finally, depending on the particular characteristics of the "multi-purpose" timer, it may be very difficult to achieve "other features" of the frequency output, such as quadrature, pulse width, etc.

  A less common method to generate frequency output is to use a "rate multiplexer". This hardware can be incorporated into an ASIC (application specific IC), an FPGA (field programmable gate array) or other custom circuitry, although it is not generally possible to utilize it in a microcontroller. This rate multiplexer makes it easy to extend the required range (so that no crossover is introduced) and to maintain the pulse accuracy (the phase matching of the update time always matches the output) And some of the shortcomings of the "multi-purpose" timer method can be overcome. Furthermore, because it is implemented by custom hardware, it is possible to easily realize "other features" of the frequency output, for example quadrature and pulse width. However, rate multiplexers require external hardware and are only sub-optimal (and non-deterministic) with respect to keeping jitter low.

  In addition to rate multiplexers, several other methods of generating frequency output are contemplated and can be implemented with custom hardware (eg, ASICs, FPGAs, etc.). However, all such options share the same basic drawbacks as the rate multiplexer scheme that there is additional parts, reduced reliability and increased costs.

  Finally, analog electronics can be used to generate the frequency output. This has been a common choice in the transition between purely mechanical devices and digital electronic devices. One example of an analog circuit is a voltage-controlled oscillator that converts voltage to frequency. Because of the analog nature, the conversion may not be 100% accurate (for example, it may convert to 999.9 Hz or 1000.1 Hz to convert 1 V to 1000 Hz. This is due to the tolerance of the analog component. Is due)). In analog electronics the frequency output has jitter close to zero, but this output has poor pulse counting accuracy. In addition, although digital feedback can be integrated into analog electronics to compensate for pulse counting accuracy, this causes delays and reduces absolute frequency accuracy.

  Thus, the art has the ability to realize "other features" including quadrature and pulse width, taking into account jitter, pulse counting accuracy, absolute accuracy of a given input clock, and certain externals. There is a need for a microcontroller device and method that overcomes the aforementioned problems by providing a serial digital frequency output that does not require hardware.

  The present invention provides the ability to easily realize the theoretical lowest jitter, maximum possible pulse counting accuracy, maximum possible absolute accuracy, "other features" (quadrature, pulse width etc) for one given input clock. It overcomes the problems mentioned above, advances the technology and does not require special external hardware.

Aspects of the Invention In accordance with one aspect of the invention, a method of generating a frequency output with a microcontroller comprises initializing an input clock signal having a predetermined period and based on the predetermined period. Calculating parameters, calculating a desired frequency based on the calculated parameters and the predetermined flow rate frequency scale, and calculating a plurality of fractional pulses, the plurality of Calculate each fractional pulse of the fractional pulse based on the desired frequency, the predetermined period of the input clock signal and the value of the preceding fractional pulse, and each fractional pulse calculated is more than half the output pulse period In some cases, the desired frequency is achieved by toggling the output state. And output.

Preferably, the value of the preceding fractional pulse is set to zero if the preceding fractional pulse is an initial fractional pulse.
Preferably, the output pulse period is calculated based on the predetermined period of the input clock signal, the calculated parameters and the predetermined flow rate frequency scale.
Preferably, the meter electronics are configured to measure the instantaneous flow rate.
Preferably, the meter electronics are configured to measure the total integrated flow based on the number of togglings in the output state and the predetermined flow frequency scale.
Preferably, the parameter is a flow rate.

  According to one aspect of the invention, a vibratory flow meter (5) is a flow meter sensor having one or more flow tubes (103A, 103B) and first and second pickoff sensors (105, 105 '). An assembly (10), a driver (104) configured to vibrate one or more flow tubes (103A, 103B), one or more pickoff sensors (105, 105 ') and a driver (104) And the meter electronics (20) initialize an input clock signal having a predetermined period and calculate parameters based on the predetermined period; Calculate the desired frequency based on the parameters and the predetermined flow rate frequency scale, calculate multiple fractional pulses, and calculate Calculates each fractional pulse of the plurality of fractional pulses based on the desired frequency, the predetermined period of the input clock signal and the value of the preceding fractional pulse, and each calculated fractional pulse is more than half the output pulse period The frequency output is generated by being configured to output a desired frequency by toggling the output state.

Preferably, the value of the preceding fractional pulse is set to zero if the preceding fractional pulse is an initial fractional pulse.
Preferably, the output pulse period is calculated based on the predetermined period of the input clock signal, the calculated parameters and the predetermined flow rate frequency scale.
Preferably, the meter electronics are configured to measure the instantaneous flow rate.
Preferably, the meter electronics are configured to measure the total integrated flow based on the number of togglings of the output condition and the predetermined flow frequency scale.
Preferably, the parameter is a flow rate.

In the following drawings, the same reference numerals represent the same parts in all the drawings, and the drawings are not necessarily to scale.
It is a figure which shows the conventional Coriolis-type flow meter. 1 is a block diagram illustrating a conventional microcontroller. FIG. 6 illustrates an exemplary frequency output in accordance with an embodiment of the present invention. 3 is a flow chart illustrating an embodiment of the present invention.

  1-4 and the following description show specific embodiments of flow meter electronics to teach those skilled in the art how to make and use the present invention in the best mode. It is done. To teach the principles of the present invention, some of the electronics of the conventional flow meter have been simplified or omitted. As will be apparent to those skilled in the art, variations of these embodiments are also within the scope of the present invention. It will also be appreciated by those skilled in the art that the components described below can be combined in various ways to form multiple variations of the invention. Accordingly, the present invention is not limited to the specific embodiments described below, but only by the claims, and their equivalents.

A conventional Coriolis flowmeter 5 is shown in FIG. By way of non-limiting example, embodiments of the present invention may include vibrating conduit sensors including Coriolis mass flowmeters and vibratory densitometers. A Coriolis flowmeter 5 according to an exemplary embodiment comprises a Coriolis flowmeter sensor assembly 10 and meter electronics 20. Meter electronics 20 are connected to sensor assembly 10 via path 100 and are adapted to provide mass flow, density, volumetric flow, total mass flow information and other information via path 26. Path 26 is
A plurality of output ports adapted to carry information in a plurality of communication channels according to known flow meter designs (not shown in FIG. 1).

  Flow meter sensor assembly 10 includes a pair of flanges 101, 101 ', a manifold 102, and flow tubes 103A, 103B. A driver 104, pickoff sensors 105 and 105 ', and a temperature sensor 107 are connected to the flow tubes 103A and 103B. The brace bars 106, 106 'serve to define the axes W and W', each flow tube being adapted to oscillate about it.

Flow meter sensor assembly 1 in a piping system (not shown in FIG. 1) carrying the fluid substance to be measured
When 0 is inserted, the substance flows through the flange 101 into the flow meter sensor assembly 10 and through the manifold 102 where the substance flows into the flow tubes 103A, 103B, the flow tube 103A , 103 B and back into the manifold 102 and out the flange 10 out of the flow meter sensor assembly 10. The flow tubes 103A, 103B are selected and appropriately attached to the manifold 102 so as to have substantially the same mass distribution, moment of inertia and elastic modules with respect to the bending axes WW, W'-W '. The flow tubes 103A, 103B extend generally parallel from the manifold 102 outward. The flow tubes 103A, 103B are arranged to be vibrated by the driver 104 in opposite directions with respect to the corresponding bending axes W and W 'respectively in a mode called the first antiphase bending mode of the flowmeter . The driver 104 has a magnet mounted on the flow tube 103 'and a coil on the opposite side mounted on the flow tube 103 so that an alternating current flows to vibrate the flow tubes. It may have any one of the known configurations. An appropriate drive signal is applied by the meter electronics 20 to the driver 104 via the lead 110.

Pickoff sensors 105, 105 'are attached to the ends of at least one of the flow tubes 103A, 103B to measure the flow tube vibrations. As the flow tubes 103A, 103B vibrate, the pickoff sensors 105, 105 'generate a first pickoff signal and a second pickoff signal. The first pickoff signal and the second pickoff signal are adapted to be applied to the leads 111, 111 '.
The temperature sensor 107 is attached to at least one flow tube of the flow tubes 103A and 103B. Temperature sensor 107 measures the temperature of the flow tube to correct the equation for the temperature of the system. The temperature signal is transmitted from the temperature sensor 107 to the flow meter electronics 20 via the path 112.

  Meter electronics 20 receives a first pickoff signal and a second pickoff signal appearing on leads 111, 111 'respectively. The flow meter electronics 20 process the first pickoff signal and the second pickoff signal to calculate the mass flow rate, density or other characteristics of the material flowing through the flow meter sensor assembly 10. This calculated information is provided by meter electronics 20 via path 26 to the utilization means (not shown in FIG. 1). In the exemplary embodiment, the flow meter electronics 20 include an exemplary microcontroller (as shown in FIG. 2) to generate the frequency output.

A block diagram of an exemplary prior art microcontroller is illustrated in FIG. In one embodiment, an exemplary microcontroller has a core and various peripherals. In some embodiments, the core may be part of a microcontroller that performs operations. In some embodiments, peripherals include system components, various memories, clocks, safety and integrity parts, analog parts, timers, communication interfaces and human-machine interfaces (HMI), (man-machine interfaces (Also known as MMI). Peripherals that can be used to generate frequency output as part of an exemplary microcontroller include timers / counters, general purpose input / output pins (GPIOs) and various serial stream interfaces such as UARTS, SPORTS, I2C , SPI and I2S. According to one aspect of the invention, the frequency output may be physically present at GPIO or physically at one of the serial based communication interfaces (eg, I2C, i2S or SPI) It may appear in the

  An exemplary embodiment of the frequency output according to the invention is shown in FIG. In this example, in operation, parameters such as flow rate are calculated periodically at 1 Hz according to a known method. Since T (s) = 1 / f (Hz), it is used to determine parameters such as flow rate for time interval (T) = 0 to 1 second, 1 to 2 seconds and 2 to 3 seconds May be

  In calculating the desired output frequency, a user selectable selectable flow rate calculation rate (m) is used (described in the following paragraph). In the example of FIG. 3, during the first period (T = 0 to 1 second), the user selects 100 g / s as the flow rate calculation rate (m), and each time the flow rate is determined, the desired corresponding to the flow rate Is also determined, and is output until the flow rate of the next period is determined. In the example of the first period, the desired frequency of 10 Hz is determined based on the calculated flow rate (m) and the frequency flow scale (x) or the frequency per rate previously determined by the user. Ru. For example, to obtain the desired frequency of 10 Hz using a known flow rate of 100 g / s, the predetermined flow rate frequency scale (x) input by the user is 0.1.

As shown in FIG. 3, if the desired frequency in the first period is 10 Hz, 10 whole pulses will be output, and each pulse transition will be toggled output state For example, high to low or low to high).
For the second period (T = 1 to 2 seconds), the flow rate is recalculated to be 8 g / s, using, for example, a known calculation method. In the example of the second period, the desired frequency of 0.8 Hz has a calculated flow rate (m) of 8 g / s and a predetermined flow rate scale (x) (x) (0.1) input by the user of 0.1 (Also known as frequency per rate).

  As shown in FIG. 3, during the second period, "0.8" full pulses will be output since the user needs a flow calculated at a frequency of 0.8 Hz . In this example, only one pulse transition (corresponding to the toggle output state) has occurred, and one full pulse has not been output yet. Thus, at T = 2 seconds, the fractional part of the pulse remains "left" and must be taken into account in the third period (T = 2 to 3 seconds). In some embodiments of the present invention, this situation is to be taken into account by the fractional pulse period (FP). As described in the algorithm and table described in the following paragraphs, the fractional pulse period (FP) has the desired frequency (m * x), an initialized input clock period (p) and a leading fractional pulse (FP) It can be calculated on the basis of: (FP = FP + (m * x * p)).

For further details of FIG. 3, in the exemplary embodiment, the initialized input clock period (p) is set to 20 Hz. In the example at 20 Hz per second, the following algorithm is executed by the exemplary microcontroller in the flow meter to determine and set the desired output state for each input clock period (p).
The basic algorithm is defined by the following calculation:

(Input): Current flow rate = m (for example, 100 g / s)
(Constant): frequency per rate = x (for example, 10 Hz = 100 g / s, x = 0.1)
Input clock period = p (for example, 20 Hz, p = 0.05 S)
(State variable): current output state
Fractional pulse

<During each input clock cycle>
Fractional pulse = Fractional pulse + (m * x * p)
If (fractional pulse> = 0.5) {
Fractional pulse = Fractional pulse-0.5;
Toggle output state}

The following table is an input clock period according to an example of the input clock period showing calculation and output of the algorithm when applied to FIG.

Temporal flow desired frequency m * x * p fractional pulse output state 0.00 s 100 g / s 10 Hz 0.5 0 + 0.5> = 0 low 0.05 s 0 + 0.5> = 0 high 0.10 s 0 + 0.5> = 0 Low 0.15s 0 + 0.5> = 0 High

0.95 s 0 + 0.5> = 0 high 1.00 s 8 g / s 0.8 Hz 0.04 0 + 0.04> =. 04 high 1.05 s. 04+. 04> =. 08 high 1.10s. 08+. 04> =. 12 high

1.15s. 12+. 04> =. 16 high 1.55 s. 44+. 04> =. 48 high 1.60 s. 48+. 04> =. 02 low 1.65s. 02+. 04> =. 06 low

1.95s. 26+. 04> =. 30 low 2.00 s 50 g / s 5 Hz 0.25. 30+. 25> =. 05 low 2.05s. 05+. 25> =. 30 low 2.10s. 30+. 25> =. 05 high 2.15 s. 05+. 25> =. 30 high 2.20 s. 30+. 25> =. 05 low

As an example of the fractional pulse (FP), the 0.8 Hz "remaining" which is not output during the second period (T = 1 to 2 seconds) is determined by the value of "0.30" in the accumulator. It is tracked (recorded) within a period (T = 2 to 3 seconds). The “0.30” used as the initial value in the third period (T = 2 to 3 seconds) is the amount left at 1.95 seconds.
Also, as shown in the above table and in FIG. 3, the time between transitions (with the output state low or high) is the period of the desired output frequency.

By exploiting the period of the desired output frequency, the flow meter can measure the instantaneous flow rate. For example, using the equation T (s) = 1 / f (Hz) and the frequency per rate (x) during an exemplary output period, the instantaneous flow can be determined by the following equation:

Instantaneous flow rate (g / s) = frequency per desired frequency (Hz) / rate (x)

Furthermore, the total integrated flow can also be determined by counting the number of toggle output states and taking into account the frequency per rate (x). For example, in FIG. 3, during the first period (T = 0 to 1 second), the total integrated flow rate of frequency (x) = 100 g / s per rate of 10 toggle output states × 0.1 is obtained. .

  In contrast to the example described above where 10 Hz corresponds to 100 g / s as described in FIG. 3, in other embodiments, 100 Hz may correspond to 100 g / s, for example. In this new example, each full pulse may correspond to 1 g. Thus, the present invention is not intended to be limited by any particular property of frequency (x) per rate.

Likewise, the invention is not limited by the frequency characteristics of the input clock period (p). As an example and mentioned in the above paragraph, the present invention provides information that accurately represents jitter at a given input clock period (p). The present invention can use the following equation to determine the percentage of maximum jitter:

Maximum jitter (%) = maximum output frequency (Hz) / input clock frequency (Hz)

Using the above equation, a 10 MHz input clock (p) is required if a frequency output of 0-10 kHz and a jitter of less than 0.1% are desired.

  A flowchart according to one embodiment of the present invention is shown in FIG. At step 401, an input clock signal having a predetermined period of a plurality of periods is initialized. Next, at step 402, it is judged if the input clock cycle has elapsed. At this time, the input clock is established as a predetermined constant frequency. For example, if the input clock is 1 MHz, each cycle of the input clock is 1 uS. Thus, the input clock is a user selectable part of the design and is therefore predetermined. In some embodiments of the present invention, the input clock may be the fastest clock in the flow meter. In operation, if the input clock is not the fastest clock, various methods such as polling or software interrupts can be used to determine when the input clock period has elapsed.

  If the input clock period has elapsed, then in step 403 it is determined whether a sufficient number of clock input periods have elapsed such that a new flow can be calculated. This relates to "a user-selectable flow rate calculation rate (m)". For example, if the input clock is 10,000 Hz and the user desires to calculate the flow rate at 10 Hz, then 100 (10,000 Hz / 10 Hz = 100) input clocks will elapse for each flow calculation.

If "YES" is determined in step 403, a new flow rate is calculated in step 404. Calculating the desired frequency (m * x) based on the calculated flow rate (m) and the predetermined flow rate frequency scale (x) input by the user by calculating the new flow rate It becomes possible. If "NO" in step 403, then in step 405 the fractional pulse period (FP) is based on the desired frequency (m * x), the initialized input clock period and the preceding fractional pulse (FP). Calculated (FP = FP + (m * x * p)). However, if the preceding fractional pulse is the first fractional pulse, the preceding fractional pulse may be set to zero.

In step 406, it is determined whether the fractional pulse period is equal to or greater than half of the output pulse period or 0.5. The output pulse period is determined in relation to frequency (p = 1 / f). Therefore, the fractional pulse period corresponds to the period in which the output period has elapsed. If the fractional pulse is not 0.5 or more, the obtained pulse period is input to step 402.
If the fractional pulse in step 406 is greater than or equal to 0.5, then in step 407 the fractional pulse is adjusted by the equation FP = FP−0.5. Here, the fractional pulse represents the remaining value and causes toggling of the output state.

At step 408, the output state is toggled to provide the desired frequency for the individual flow rates if the fractional pulse period is greater than or equal to half of the output pulse period. The resulting fractional pulse is then input to step 402 and operation in the loop is continued.
Some exemplary embodiments use serial output hardware that is typically "on-board" to a microcontroller to reduce processing load. This type of hardware may include, but is not limited to, I2S, SPI, USARTS / ARTS, "SPORTS" and several types of JTAG ports. Furthermore, DMA can also be used to reduce the processing load.

  To incorporate various types of serial output hardware (e.g., SPI, DMA, etc.), "blocks" of output states are precomputed, then presented to the hardware and output at "input clock rate." This is advantageous in that it reduces bandwidth requirements by reducing the overhead of each power calculation. For example, in the case of SPI, it is possible to pre-compute blocks of 8, 16 or 32 output states and then output "automatically" with standard SPI hardware. In addition, it is possible to use DMA to increase the block size to any desired size.

Advantageously, the invention can be easily enhanced by incorporating any of the "other features" (quadrature, pulse width, etc.).
Advantageously, the present invention is fully scalable over any desired frequency output range, limited only by the particular data type selected to perform the operation and the resolution of the input clock frequency. Ru. In some embodiments, the standard data types include integer types (eg, 8-bit, 16-bit, 32-bit or 64-bit) or floating-point types (typically, single precision or double precision according to IEEE 534). Can.

This specification describes specific embodiments to teach those skilled in the art how to make or use the best mode of the invention. Portions of the prior art have been simplified or omitted to teach the principles of the present invention. As will be apparent to those skilled in the art, variations of these embodiments are also included within the scope of the invention.
The detailed description of the embodiments described above is not exhaustive of all embodiments considered by the inventor as being within the scope of the present invention. Rather, as will be apparent to those skilled in the art, some components of the above-described embodiments may be variously combined or removed to create further embodiments, and such Additional embodiments are also within the teaching of the present invention. Also, as will be apparent to those skilled in the art, the embodiments described above may be combined in whole or in part to create further embodiments within the scope of the techniques, teachings of the present invention.
While specific embodiments or examples of the invention have been described for the purpose of illustration, it will be appreciated by those skilled in the art that various modifications can be made within the scope of the invention. The teachings described herein may be applied to embodiments different from the embodiments described above and in the corresponding figures. Accordingly, the scope of the invention is to be determined by the following claims.

The following table is an input clock period according to an example of the input clock period showing calculation and output of the algorithm when applied to FIG.

Temporal flow desired frequency m * x * p fractional pulse output state 0.00 s 100 g / s 10 Hz 0.5 0 + 0.5> = 0 low 0.05 s 0 + 0.5> = 0 high 0.10 s 0 + 0.5> = 0 Low 0.15s 0 + 0.5> = 0 High

0.95 s 0 + 0.5> = 0 high 1.00 s 8 g / s 0.8 Hz 0.04 0 + 0.04> =. 04 high 1.05 s. 04+. 04> =. 08 high 1.10s. 08+. 04> =. 12 high

1.15s. 12+. 04> =. 16 high 1.55 s. 44+. 04> =. 48 high 1.60 s. 48+. 04> =. 02 low 1.65s. 02+. 04> =. 06 low

1.95s. 26+. 04> =. 30 low 2.00 s 50 g / s 5 Hz 0.25. 30+. 25> =. 05 high 2.05 s. 05+. 25> =. 30 high 2.10 s. 30+. 25> =. 05 low 2.15 s. 05+. 25> =. 30 low 2.20 s. 30+. 25> =. 05 high

Claims (12)

A method of generating a frequency output with a microcontroller,
Initializing an input clock signal having a predetermined period;
Calculating parameters based on the predetermined period;
Calculating a desired frequency based on the parameters and a predetermined flow frequency scale;
Calculating a plurality of fractional pulses, wherein each fractional pulse of the plurality of fractional pulses is calculated based on the desired frequency, the predetermined period of the input clock signal and the value of the preceding fractional pulse , Step, and
Outputting the desired frequency by toggling an output state if each calculated fractional pulse is greater than or equal to half an output pulse period;
Method, including   The method according to claim 1, wherein the value of the preceding fractional pulse is set to 0 if the preceding fractional pulse is an initial fractional pulse.   The method of claim 1, wherein the output pulse period is calculated based on the predetermined period of the input clock signal, the calculated parameter and the predetermined flow rate frequency scale.   The method of claim 1, wherein the meter electronics are configured to measure an instantaneous flow rate.   The method according to claim 1, wherein the meter electronics are configured to measure a total integrated flow based on the number of togglings in the output condition and the predetermined flow frequency scale.   The method according to claim 1, wherein the parameter is a flow rate. A vibrating flow meter (5),
A flowmeter sensor assembly (10) having one or more flow tubes (103A, 103B) and first and second pickoff sensors (105, 105 ');
A driver (104) configured to vibrate the one or more flow tubes (103A, 103B);
Meter electronics (20) coupled with the first and second pickoff sensors (105, 105 ') and coupled with the driver (104);
Said meter electronics (20)
Initialize an input clock signal having a predetermined period,
Calculating parameters based on the predetermined period,
Calculate the desired frequency based on the parameters and the predetermined flow frequency scale,
Calculate multiple fractional pulses,
The calculation calculates each fractional pulse of the plurality of fractional pulses based on the desired frequency, the predetermined period of the input clock signal and the value of the preceding fractional pulse,
The apparatus is configured to generate a frequency output by being configured to output the desired frequency by toggling an output state when each calculated fractional pulse is greater than or equal to half an output pulse period. Vibration-type flow meter (5), which is a meter electronic device. The vibratory flow meter (5) according to claim 7, wherein the value of the preceding fractional pulse is set to 0 if the preceding fractional pulse is an initial fractional pulse.   8. The system of claim 7, wherein the output pulse period is configured to be calculated based on the predetermined period of the input clock signal, the calculated parameter and the predetermined flow rate frequency scale. Vibratory flowmeter (5).   8. The apparatus of claim 7, wherein the meter electronics are configured to measure instantaneous flow.   The vibratory flow meter (5) according to claim 7, wherein the meter electronics are configured to determine a total integrated flow based on the number of togglings in the output condition and the predetermined flow frequency scale.   The vibratory flow meter (5) according to claim 7, wherein the parameter is a flow rate.

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