Abstrict Flow meter electronics are described for providing a flow rate
of a material flowing through a flow meter sensor of a Coriolis
flow meter. The flow meter electronics comprise a processing system
and a single output port. The processing system receives pick-off
signals from the flow meter sensor and processes the pick-off signals
to determine the flow rate. The processing system receives an instruction
for a frequency output signal or a digital communication protocol
signal. If the instruction is for a frequency output signal, then
the processing system processes the flow rate to generate a frequency
output signal and transmits the frequency output signal over the
single output port. If the instruction is for a digital communication
protocol signal, then the processing system processes the flow rate
to generate a digital communication protocol signal and transmits
the digital communication protocol signal over the single output
port.
Claims What is claimed is:
1. Flow meter electronics, comprising: a single port; and a processing
system coupled to said single port and configured to: process signals
from a flow meter to determine flow meter data; generate a frequency
output signal having a frequency that represents the flow meter
data and transmit the frequency output signal over the single port
if an output instruction comprises a frequency output instruction;
and generate a digital communication protocol signal that represents
the flow meter data and transmit the digital communication protocol
signal over the single port if an output instruction comprises a
digital communication output instruction.
2. The flow meter electronics of claim 1 wherein said processing
system is further configured to: determine a direction of flow of
said material; if said direction of flow is in a first direction,
then generate said frequency output signal to have a duty cycle
below 0.5; and if said direction of flow is in a second direction,
then generate said frequency output signal to have a duty cycle
above 0.5.
3. The flow meter electronics of claim 1 wherein said processing
system is further configured to: determine if a fault has occurred;
and generate said frequency output signal to have a predetermined
frequency responsive to determining said fault.
4. The flow meter electronics of claim 1 wherein said processing
system is further configured to receive an input signal through
the single port, with the input signal including the output instruction.
5. The flow meter electronics of claim 1 wherein said processing
system is further configured to receive an input signal through
the single port during a predetermined time period after a power
cycle event, with the input signal including the output instruction.
6. The flow meter electronics of claim 1 wherein said processing
system is further configured to receive an input signal through
the single port during a predetermined time period after a power
up event, with the input signal including the output instruction.
7. The flow meter electronics of claim 1 wherein said flow meter
data comprises a mass flow rate.
8. The flow meter electronics of claim 1 wherein said flow meter
data comprises a volumetric flow rate.
9. The flow meter electronics of claim 1 wherein said flow meter
data comprises a net volumetric flow rate.
10. A method of operating flow meter electronics, comprising: processing
signals from a flow meter to determine flow meter data; generating
a frequency output signal having a frequency that represents the
flow meter data and transmitting the frequency output signal over
a single port of the flow meter electronics if an output instruction
comprises a frequency output instruction; and generating a digital
communication protocol signal that represents the flow meter data
and transmitting the digital communication protocol signal over
the single port if an output instruction comprises a digital communication
output instruction.
11. The method of claim 10 further comprising: determining a direction
of flow of said material; if said direction of flow is in a first
direction, then generating said frequency output signal to have
a duty cycle below 0.5; and if said direction of flow is in a second
direction, then generating said frequency output signal to have
a duty cycle above 0.5.
12. The method of claim 10 further comprising: determining if a
fault has occurred; and generating said frequency output signal
to have a predetermined frequency responsive to determining said
fault.
13. The method of claim 10 further comprising: receiving an input
signal through the single port, with the input signal including
the output instruction.
14. The method of claim 10 further comprising: receiving an input
signal through the single port during a predetermined time period
after a power cycle event, with the input signal including the output
instruction.
15. The method of claim 10 further comprising: receiving an input
signal through the single port during a predetermined time period
after a power up event, with the input signal including the output
instruction.
16. The method of claim 10 wherein said flow meter data comprises
a mass flow rate.
17. The method of claim 10 wherein said flow meter data comprises
a volumetric flow rate.
18. The method of claim 10 wherein said flow meter data comprises
a net volumetric flow rate.
19. A software product for operating flow meter electronics, said
software product comprising: flow meter electronics software configured
when executed by a processing system to direct the processing system
to process signals from a flow meter to determine flow meter data,
generate a frequency output signal having a frequency that represents
the flow meter data and transmit the frequency output signal over
a single port of the flow meter electronics if an output instruction
comprises a frequency output instruction, and generate a digital
communication protocol signal that represents the flow meter data
and transmit the digital communication protocol signal over the
single port if an output instruction comprises a digital communication
output instruction; and a storage media configured to store said
flow meter electronics software.
20. The software product of claim 19 wherein said flow meter electronics
software is further configured to direct said processing system
to: determine a direction of flow of said material; if said direction
of flow is in a first direction, then generate said frequency output
signal to have a duty cycle below 0.5; and if said direction of
flow is in a second direction, then generate said frequency output
signal to have a duty cycle above 0.5.
21. The software product of claim 19 wherein said flow meter electronics
software is further configured to direct said processing system
to: determine if a fault has occurred; and generate said frequency
output signal to have a predetermined frequency responsive to determining
said fault.
22. The software product of claim 19 wherein said flow meter electronics
software is further configured to direct said processing system
to receive an input signal through the single port, with the input
signal including the output instruction.
23. The software product of claim 19 wherein said flow meter electronics
software is further configured to direct said processing system
to receive an input signal through the single port during a predetermined
time period after a power cycle event, with the input signal including
the output instruction.
24. The software product of claim 19 wherein said flow meter electronics
software is further configured to direct said processing system
to receive an input signal through the single port during a predetermined
time period after a power up event, with the input signal including
the output instruction.
25. The software product of claim 19 wherein said flow meter data
comprises a mass flow rate.
26. The software product of claim 19 wherein said flow meter data
comprises a volumetric flow rate.
27. The software product of claim 19 wherein said flow meter data
comprises a net volumetric flow rate.
Description RELATED APPLICATIONS
[0001] This application is a Continuation of U.S. patent application
Ser. No. 10/261057 filed on Sep. 30 2002.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention is related to the field of flow meters, and
in particular, to flow meter electronics capable of outputting either
a frequency output signal or a digital communication protocol signal
over a single output port.
[0004] 2. Statement of the Problem
[0005] Coriolis mass flow meters measure mass flow and other information
with respect to materials flowing through a pipeline as disclosed
in U.S. Pat. No. 4491025 issued to J. E. Smith, et al., of Jan.
1 1985 and Re. 31450 to J. E. Smith of Feb. 11 1982. These flow
meters typically comprise a flow meter electronics portion and a
flow meter sensor portion. Flow meter sensors have one or more flow
tubes of a straight or curved configuration. Each flow tube configuration
has a set of natural vibration modes, which may be of a simple bending,
torsional, radial, or coupled type. Each flow tube is driven to
oscillate at resonance in one of these natural vibration modes.
The natural vibration modes of the vibrating, material filled systems
are defined in part by the combined mass of the flow tubes and the
material within the flow tubes. When there is no material flowing
through a Coriolis flow meter sensor, all points along the flow
tubes oscillate with a substantially identical phase. As material
flows through the flow tubes, Coriolis accelerations cause points
along the flow tubes to have a different phase. The phase on the
inlet side of the flow meter sensor lags the driver, while the phase
on the outlet side of the flow meter sensor leads the driver.
[0006] Coriolis flow meter sensors typically include two pick-offs
for producing sinusoidal signals representative of the motion of
the flow tubes at different points along the flow tubes. A phase
difference of the sinusoidal signals received from the pick-offs
is calculated by the flow meter electronics. The phase difference
between the pick-off signals is proportional to the mass flow rate
of the material flowing through the flow meter sensor. An example
of a Coriolis flow meter is described below in FIG. 1.
[0007] The flow meter electronics receive the pick-off signals
from the pick-offs. The flow meter electronics process the pick-off
signals to compute a mass flow rate, a density, or another property
of the material passing through the flow meter sensor. The flow
meter electronics typically have multiple output ports or multiple
communication channels for outputting the mass flow rate, the density,
or other information. For instance, typical flow meter electronics
have a milliamp output, a discreet voltage output, a digital communications
protocol output, and a frequency output. Each output has its own
physical port. The flow meter electronics with multiple output ports
provide a great deal of versatility to users, which can be useful
for certain applications. Unfortunately, flow meter electronics
with multiple output ports can be expensive and may have more functionality
than is needed for simple applications.
[0008] To help solve this problem, less complex and cheaper flow
meter electronics have been developed. The less complex flow meter
electronics still receive the pick-off signals from the pick-offs,
and process the pick-off signals to compute a mass flow rate, a
density, or another property of the material passing through the
flow meter sensor. The less complex flow meter electronics differ
by having a single output port. The less complex flow meter electronics
only generate a digital communication protocol signal that represents
the mass flow rate, the density, or the other properties. Unfortunately,
some users have legacy systems that are configured to receive a
frequency or pulse signal and do not understand a digital communication
protocol signal.
[0009] Traditionally, the flow meter industry mainly involves mechanical
flow meters, such as positive displacement meters, oval gear, or
turbine flow meters. These mechanical flow meters generate a pulse
signal when the chamber, gear, or blade passes through a magnetic
field, or from a magnetic rotating component on a shaft. Legacy
systems receive the pulse signal and provide a read out of the flow
rate, adjust a valve based on the flow rate, or perform another
function. Newer electronic flow meters have also been configured
to generate a pulse signal proportional to a flow rate to interface
with these legacy systems. Unfortunately, no flow meter electronics
have been developed that will interface with legacy systems and
current flow systems, but are cost effective for less complex applications.
SUMMARY OF THE SOLUTION
[0010] The invention helps solve the above problems with flow meter
electronics that can be programmed to either output a frequency
output signal or a digital communication protocol signal over a
single output port. The invention advantageously provides flow meter
electronics that are cheaper and better suited for less complex
applications. The flow meter electronics are also capable of interfacing
with legacy systems with the frequency output signal or interfacing
with more modern systems with the digital communication protocol
signal.
[0011] One embodiment of the invention includes flow meter electronics
for providing a flow rate of a material flowing through a flow meter
sensor of a Coriolis flow meter. The flow meter electronics comprise
a processing system and a single output port. The processing system
receives pick-off signals from the flow meter sensor and processes
the pick-off signals to determine the flow rate of the material.
The processing system receives an instruction for a frequency output
signal or a digital communication protocol signal. If the instruction
is for a frequency output signal, then the processing system processes
the flow rate to generate a frequency output signal having a frequency
proportional to the flow rate, and transmits the frequency output
signal over the single output port. If the instruction is for a
digital communication protocol signal, then the processing system
processes the flow rate to generate a digital communication protocol
signal that represents the flow rate, and transmits the digital
communication protocol signal over the single output port.
[0012] In another embodiment, the processing system determines
a direction of flow of the material. If the direction of flow is
in a forward direction, then the processing system generates the
frequency output signal to have a duty cycle below 0.5. If the direction
of flow is in a reverse direction, then the processing system generates
the frequency output signal to have a duty cycle above 0.5.
[0013] In another embodiment of the invention, the processing system
determines if a fault has occurred. The processing system generates
the frequency output signal having a predetermined frequency responsive
to determining the fault.
[0014] The invention also includes other embodiments described
below.
[0015] The following depict aspects of the invention. One aspect
is flow meter electronics for providing a flow rate of a material
flowing through a flow meter sensor of a Coriolis flow meter, said
flow meter electronics comprising:
[0016] a single output port; and
[0017] a processing system coupled to said single output port and
configured to:
[0018] receive pick-off signals from said flow meter sensor,
[0019] process said pick-off signals to determine said flow rate
of said material,
[0020] receive an instruction for a frequency output signal or
a digital communication protocol signal,
[0021] if said instruction is for said frequency output signal,
then said processing system is further configured to process said
flow rate to generate said frequency output signal having a frequency
proportional to said flow rate, and transmit said frequency output
signal over said single output port, and
[0022] if said instruction is for said digital communication protocol
signal, then said processing system is further configured to process
said flow rate to generate said digital communication protocol signal
that represents said flow rate, and transmit said digital communication
protocol signal over said single output port.
[0023] Preferably, the processing system is further configured
to:
[0024] determine a direction of flow of said material;
[0025] if said direction of flow is in a first direction, then
generate said frequency output signal to have a duty cycle below
0.5; and
[0026] if said direction of flow is in a second direction, then
generate said frequency output signal to have a duty cycle above
0.5.
[0027] Preferably, the processing system is further configured
to:
[0028] determine if a fault has occurred; and
[0029] generate said frequency output signal having a predetermined
frequency responsive to determining said fault.
[0030] Preferably, the processing system is further configured
to receive said instruction over said single output port from a
user.
[0031] Preferably, the flow rate comprises a mass flow rate.
[0032] Alternatively, the flow rate comprises a volumetric flow
rate.
[0033] Alternatively, the flow rate comprises a net volumetric
flow rate.
[0034] Another aspect is a method of operating flow meter electronics
for providing a flow rate of a material flowing through a flow meter
sensor of a Coriolis flow meter, said method comprising the steps
of:
[0035] receiving pick-off signals from said flow meter sensor;
[0036] processing said pick-off signals to determine said flow
rate of said material;
[0037] receiving an instruction for a frequency output signal or
a digital communication protocol signal;
[0038] if said instruction is for a frequency output signal, then
processing said flow rate to generate said frequency output signal
having a frequency proportional to said flow rate and transmitting
said frequency output signal over a single output port; and
[0039] if said instruction is for said digital communication protocol
signal, then processing said flow rate to generate said digital
communication protocol signal that represents said flow rate and
transmitting said digital communication protocol signal over said
single output port.
[0040] Preferably, the method further comprises:
[0041] determining a direction of flow of said material;
[0042] if said direction of flow is in a first direction, then
generating said frequency output signal to have a duty cycle below
0.5; and
[0043] if said direction of flow is in a second direction, then
generating said frequency output signal to have a duty cycle above
0.5.
[0044] Preferably, the method further comprises:
[0045] determining if a fault has occurred; and
[0046] generating said frequency output signal having a predetermined
frequency responsive to determining said fault.
[0047] Preferably, the method further comprises receiving said
instruction over said single output port from a user.
[0048] Preferably, the flow rate comprises a mass flow rate.
[0049] Alternatively, the flow rate comprises a volumetric flow
rate.
[0050] Alternatively, the flow rate comprises a net volumetric
flow rate.
[0051] Another aspect is a software product for providing a flow
rate of a material flowing through a flow meter sensor of a Coriolis
flow meter, said software product comprising:
[0052] flow meter software configured when executed by a processing
system to direct the processing system to receive pick-off signals
from said flow meter sensor, process said pick-off signals to determine
said flow rate of said material, receive an instruction for a frequency
output signal or a digital communication protocol signal, process
said flow rate to generate said frequency output signal having a
frequency proportional to said flow rate and transmit said frequency
output signal over a single output port if said instruction is for
said frequency output signal, and process said flow rate to generate
said digital communication protocol signal that represents said
flow rate and transmit said digital communication protocol signal
over said single output port if said instruction is for said digital
communication protocol signal; and
[0053] a storage media configured to store said flow meter software.
[0054] Preferably, the flow meter software is further configured
to direct said processing system to:
[0055] determine a direction of flow of said material;
[0056] if said direction of flow is in a first direction, then
generate said frequency output signal to have a duty cycle below
0.5; and
[0057] if said direction of flow is in a second direction, then
generate said frequency output signal to have a duty cycle above
0.5.
[0058] Preferably, the flow meter software is further configured
to direct said processing system to:
[0059] determine if a fault has occurred; and
[0060] generate said frequency output signal having a predetermined
frequency responsive to determining said fault.
[0061] Preferably, the flow meter software is further configured
to direct said processing system to receive said instruction over
said single output port from a user.
[0062] Preferably, the flow rate comprises a mass flow rate.
[0063] Alternatively, the flow rate comprises a volumetric flow
rate.
[0064] Alternatively, the flow rate comprises a net volumetric
flow rate.
DESCRIPTION OF THE DRAWINGS
[0065] The same reference number represents the same element on
all drawings.
[0066] FIG. 1 illustrates a Coriolis flow meter in the prior art.
[0067] FIG. 2 illustrates flow meter electronics having multiple
output ports in the prior art.
[0068] FIG. 3 illustrates flow meter electronics for a Coriolis
flow meter in an example of the invention.
[0069] FIG. 4 illustrates an example of a Coriolis flow meter connected
to a user system in an example of the invention.
[0070] FIG. 5 illustrates frequency output signals in an example
of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0071] FIGS. 1-5 and the following description depict specific
examples of flow meter electronics to teach those skilled in the
art how to make and use the best mode of the invention. For the
purpose of teaching inventive principles, some conventional aspects
of the flow meter electronics have been simplified or omitted. Those
skilled in the art will appreciate variations from these examples
that fall within the scope of the invention. Those skilled in the
art will appreciate that the features described below can be combined
in various ways to form multiple variations of the invention. As
a result, the invention is not limited to the specific examples
described below, but only by the claims and their equivalents.
[0072] Prior Art Coriolis Flow Meter--FIGS. 1-2
[0073] FIG. 1 illustrates a Coriolis flow meter 5 in the prior
art. Coriolis flow meter 5 comprises a Coriolis flow meter sensor
10 and Coriolis flow meter electronics 20. Flow meter electronics
20 is connected to flow meter sensor 10 via path 100 to provide
for mass flow rate, density, volume flow rate, totalized mass flow
information, and other information over path 26. Path 26 represents
multiple output ports carrying information on multiple channels
of communications as is depicted in FIG. 2. A variety of commercially
available Coriolis flow meters providing these measurements may
be purchased from Micro Motion of Boulder, Colo.
[0074] Flow meter sensor 10 includes a pair of flanges 101 and
101', manifold 102 and flow tubes 103A and 103B. Connected to flow
tubes 103A and 103B are driver 104 and pick-off sensors 105 and
105', and temperature sensor 107. Brace bars 106 and 106' serve
to define the axis W and W' about which each flow tube 103A and
103B oscillates.
[0075] When flow meter sensor 10 is inserted into a pipeline system
(not shown in FIG. 1) which carries a material that is being measured,
the material enters flow meter sensor 10 through flange 101 passes
through manifold 102 where the material is directed to enter flow
tubes 103A and 103B, flows through flow tubes 103A and 103B and
back into manifold 102 from where it exits flow meter sensor 10
through flange 101'.
[0076] Flow tubes 103A and 103B are selected and appropriately
mounted to the manifold 102 to have substantially the same mass
distribution, moments of inertia, and elastic modules about bending
axes W-W and W'-W', respectively. The flow tubes 103A-103B extend
outwardly from manifold 102 in an essentially parallel fashion.
[0077] Flow tubes 103A-103B are driven by driver 104 in opposite
directions about their respective bending axes W and W' at what
is termed the first out of phase bending mode of the flow meter.
Driver 104 may comprise any one of many well known arrangements,
such as a magnet mounted to flow tube 103A and an opposing coil
mounted to flow tube 103B and through which an alternating current
is passed for vibrating both flow tubes. A suitable drive signal
is applied by flow meter electronics 20 via lead 110 to driver
104.
[0078] Pick-off sensors 105 and 105' are affixed to at least one
of flow tubes 103A and 103B on opposing ends of the flow tube to
measure oscillation of the flow tubes. As flow tubes 103A-103B vibrate,
pick-off sensors 105-105' generate a first pick-off signal and a
second pick-off signal. The first and second pick-off signals are
applied to leads 111 and 111'.
[0079] Temperature sensor 107 is affixed to at least one of flow
tubes 103A and 103B. Temperature sensor 107 measures the temperature
of the flow tube in order to modify equations for the temperature
of the system. Path 112 carries temperature signals from temperature
sensor 107 to flow meter electronics 20.
[0080] Flow meter electronics 20 receive the first and second pick-off
signals appearing on leads 111 and 111', respectively. Flow meter
electronics 20 process the first and second pick-off signals to
compute the mass flow rate, the density, or other property of the
material passing through flow meter sensor 10. This computed information
is applied by meter electronics 20 over path 26 to a utilization
means (not shown in FIG. 1).
[0081] FIG. 2 illustrates flow meter electronics 20 having multiple
output ports 201-204 in the prior art. In FIG. 2 flow meter sensor
10 is depicted in block diagram form for the sake of simplicity.
Flow meter electronics 20 comprises processing system 208 and output
ports 201-204. Output ports 201-204 make up path 26 in FIG. 1. Processing
system 208 outputs different types of signals over output ports
201-204. Processing system 208 outputs a milliamp signal over output
port 201. Processing system 208 outputs a discreet voltage signal
over output port 202. Processing system 208 outputs a digital communication
protocol signal over output port 203. Processing system 208 outputs
a frequency signal or pulse signal over output port 204. Unfortunately,
flow meter electronics 20 with multiple output ports 201-204 can
be expensive and may have more functionality than is needed for
simple applications.
[0082] There also exists other prior art flow meter electronics
that are simpler and lower-cost than flow meter electronics 20.
The flow meter electronics have only one output port, such as output
port 203 that outputs a digital communication protocol signal.
One problem with these types of flow meter electronics is that they
can only output a digital communication protocol signal and some
legacy systems do not understand a digital communication protocol
signal.
[0083] Flow Meter Electronics--FIG. 3
[0084] FIG. 3 illustrates flow meter electronics 302 for a Coriolis
flow meter 300 in an example of the invention. Coriolis flow meter
300 is illustrated in block diagram form for simplicity. Flow meter
electronics 302 is coupled to flow meter sensor 10 over path 100.
Flow meter electronics 302 is comprised of processing system 304
coupled to a single output port 306. Single output port 306 provides
a single channel of communications out of flow meter electronics
302. Flow meter electronics 302 may have one or more power connections
(not shown) in addition to single output port 306.
[0085] Flow meter sensor 10 operates as described in FIG. 1 to
transmit pick-off signals to flow meter electronics 302 over path
100 as a material flows through flow meter sensor 10. Flow meter
sensor 10 could also transmit other signals, such as a temperature
signal, to flow meter electronics 302. Processing system 304 receives
the pick-off signals from flow meter sensor 10. Processing system
304 processes the pick-off signals to determine a flow rate of the
material flowing through flow meter sensor 10.
[0086] Processing system 304 also receives an instruction 318 for
a frequency output signal or a digital communication protocol signal.
The frequency output signal comprises any signal that represents
a single property of a material flowing through a flow meter sensor,
such as a square wave signal or a sinusoidal signal. The frequency
of the frequency output signal represents a property of a material
flowing through a flow meter sensor. For instance, a frequency output
signal may represent a mass flow rate, wherein the frequency of
the frequency output signal is proportional to the mass flow rate.
A digital communication protocol signal comprises any signal, that
represents multiple properties of a material flowing through a flow
meter sensor, that can be read by conventional digital processing
circuitry. For instance, a digital communication protocol signal
may represent a mass flow rate, a density, and other properties.
Instruction 318 could be transmitted to flow meter electronics 302
by a user who is programming flow meter electronics 302.
[0087] If instruction 318 is for a frequency output signal, then
processing system 304 processes the flow rate to generate a frequency
output signal 322. Frequency output signal 322 has a frequency proportional
to the flow rate of the material. Processing system 304 transmits
frequency output signal 322 over single output port 306.
[0088] If instruction 318 is for a digital communication protocol
signal, then processing system 304 processes the flow rate to generate
a digital communication protocol signal 324. Digital communication
protocol signal 324 represents the flow rate of the material. Processing
system 304 transmits digital communication protocol signal 324 over
single output port 306. Signal 326 represents either frequency output
signal 322 or digital communication protocol signal 324 depending
on which signal that processing system 304 transmitted over single
output port 306. Based on this disclosure, those skilled in the
art will appreciate how to modify existing flow meter electronics
to make flow meter electronics 302.
[0089] Flow meter electronics 302 is advantageously less expensive
to build and simpler to operate than flow meter electronics having
multiple output ports. At the same time, flow meter electronics
302 provides flexibility to a user by allowing the user to program
flow meter electronics 302 to output either a frequency output signal
322 or a digital communication protocol signal 324.
[0090] In one embodiment of the invention, processing system 304
determines a direction of flow of the material. If the direction
of flow is in a forward direction, then processing system 304 generates
frequency output signal 322 to have a duty cycle below 0.5. If the
direction of flow is in a reverse direction, then processing system
304 generates frequency output signal 322 to have a duty cycle above
0.5.
[0091] In another embodiment, processing system 304 determines
if a fault has occurred. The fault may have occurred in flow meter
sensor 10 flow meter electronics 302 or in the pipeline (not shown)
connected to flow meter sensor 10. Processing system 304 generates
frequency output signal 322 having a predetermined frequency responsive
to determining the fault.
[0092] In another embodiment of the invention, the above-described
flow meter electronics 302 may be comprised of instructions that
are stored on storage media. The instructions can be retrieved and
executed by a processor. Some examples of instructions are software,
program code, and firmware. Some examples of storage media are memory
devices, tape, disks, integrated circuits, and servers. The instructions
are operational when executed by the processor to direct the processor
to operate in accord with the invention. The term "processor"
refers to a single processing device or a group of inter-operational
processing devices. Some examples of processors are computers, integrated
circuits, and logic circuitry. Those skilled in the art are familiar
with instructions, processors, and storage media.
[0093] Example of Flow Meter Electronics--FIGS. 4-5
[0094] FIG. 4 illustrates an example of a Coriolis flow meter 400
connected to a user system 406 in an example of the invention. Flow
meter electronics 404 is coupled to flow meter sensor 402 over path
420. Flow meter electronics 404 is coupled to user system 406 over
path 422. Flow meter electronics 404 is comprised of processing
system 414 coupled to a single output port 416.
[0095] Flow meter electronics 404 is configured to output a frequency
output signal or a digital communication protocol signal. A user
430 can program flow meter electronics 404 to output the frequency
output signal or the digital communication protocol signal with
user system 406. User system 406 could be a computer, a display,
or any other system or apparatus that interfaces user 430 with flow
meter electronics 404.
[0096] On power up, single output port 416 acts as an input/output
port for a time period, such as 5 seconds. Single output port 416
also acts as an input/output port for a time period after a power
cycle. During this time period, processing system 414 waits for
digital signals received over single output port 416. User 430 can
program flow meter electronics 404 to operate in frequency mode
or digital mode, select other operating options, or transmit operating
parameters or other information to flow meter electronics 404 by
transmitting instructions to flow meter electronics 404. Frequency
mode means that flow meter electronics 404 outputs a frequency output
signal. Digital mode means that flow meter electronics 404 outputs
a digital communication protocol signal.
[0097] Following the time period after power up, processing system
414 operates in either frequency mode or digital mode. The operating
mode can be a default programmed into processing system 414 or be
programmed by user 430.
[0098] In frequency mode, processing system 414 receives the pick-off
signals from flow meter sensor 402 and processes the pick-off signals
to determine a flow rate of the material flowing through flow meter
sensor 402. The flow rate may represent a mass flow rate, a volumetric
flow rate, or a net volumetric flow rate. Processing system 414
generates frequency output signal 424 based on the flow rate of
the material. Frequency output signal 424 has a frequency proportional
to the flow rate of the material. Frequency output signal 424 may
be scalable to 10000 Hz.
[0099] Processing system 414 also determines a direction of flow
of the material flowing through flow meter sensor 402. Processing
system 414 generates frequency output signal 424 based on the direction
of flow of the material. If the direction of flow is in a forward
direction, then frequency output signal 424 has a duty cycle below
0.5. If the direction of flow is in a reverse direction, then frequency
output signal 424 has a duty cycle above 0.5. Examples of frequency
output signal 424 are depicted in FIG. 5. Processing system 414
transmits frequency output signal 424 to single output port 416.
[0100] Processing system 414 also determines if a fault has occurred.
If a fault has occurred, processing system 414 generates frequency
output signal 424 to have a fixed, high frequency. Processing system
414 operates in frequency mode until a power cycle occurs.
[0101] In digital mode, processing system 414 receives the pick-off
signals from flow meter sensor 402 and processes the pick-off signals
to determine the flow rate of the material flowing through flow
meter sensor 402. Processing system 414 generates digital communication
protocol signal 426 based on the flow rate of the material. Digital
communication protocol signal 426 represents the flow rate of the
material. Processing system 414 operates in digital mode until a
power cycle occurs.
[0102] In digital mode, processing system 414 can also determine
a direction of flow of the material flowing through flow meter sensor
402 and determine if a fault has occurred. Processing system 414
outputs digital communication protocol signal 426 representing the
direction of flow of the material or fault information. |