Digital communication apparatus and method, the mass flowmenter of a kind of mass flowmenterTechnical field
The present embodiments relate to digital communication apparatus and the side of digital communicating field, more particularly to a kind of mass flowmenterMethod, mass flowmenter.
Background technology
At present, in industrial stokehold instrument simulate instrument use still occupy an leading position, its with unified two-wire system 4~20mA analog signals are used as standard signal.It is more and more wider with the application of intelligence instrument so that field apparatus and control room equipmentBetween the mutual transmission of information be also continuously increased.
Because existing Coriolis force mass flowmenter uses 4~20mA analog currents loop, so in a cableLast time unidirectionally can only transmit a parameter to control room equipment, can not meet digitlization, the communication control procedure of multi-parameter.SoAnd, it is difficult to realize to replace simulation instrument with digital intellectualization instrument in a short time.
In view of the above-mentioned problems, not yet proposing effective solution at present.
The content of the invention
The present invention provides a kind of digital communication apparatus and method, mass flowmenter of mass flowmenter, can be in compatibility biographyWhile simulation system of uniting, realize that multi-parameter is transmitted using digital communication.
In a first aspect, the embodiments of the invention provide a kind of digital communication apparatus of mass flowmenter, including：MicroprocessorDevice, HART (Highway Addressable Remote Transducer, the opening of highway addressable remote transducerCommunication protocol) modem and digital analog converter, wherein：
The microprocessor, is connected to the digital analog converter and the HART modem, for the digital-to-analogueConverter sends the first data, and sends the second data to the HART modem；
The HART modem, is connected to the digital analog converter, for being modulated to second data, toThe digital analog converter sends the signal after modulation；
The digital analog converter, for handling first data, obtains analog current signal, superposition output instituteState the signal after analog current signal and the modulation.
Second aspect, the embodiment of the present invention additionally provides a kind of mass flowmenter, including such as any embodiment institute of the present inventionThe digital communication apparatus stated.
The third aspect, the embodiment of the present invention additionally provides a kind of digital communication method of mass flowmenter, applied to such as originallyThe digital communication apparatus of mass flowmenter described in invention any embodiment, methods described includes：
Digital analog converter receives the first data that microprocessor is sent, and first data are handled, simulatedCurrent signal；
The digital analog converter receives the signal after the modulation that HART modem is sent, wherein the letter after the modulationNumber it is that the HART modem is modulated what is obtained to the second data that the microprocessor is sent；
The digital analog converter superposition exports the signal after the analog current signal and the modulation.
The present invention is modulated the data signal after being modulated to parametric variable by HART modem, and digital-to-analogue turnsParallel operation handles parametric variable progress and obtains analog current signal, after digital analog converter superposition output analog current signal and modulationData signal, to solve existing mass flowmenter can only export single parameter variable, it is impossible to meet multi-parameter output demandProblem, can realize that multi-parameter is transmitted while compatible conventional analog systems using digital communication, same on a cableWhen transmission of analogue signal and data signal superposed thereon, both do not interfere with each other.In addition, using superposition output, without newly-builtLink, is transformed simple and convenient so that the Reconstruction in field cost of existing mass flowmenter is relatively low.
Brief description of the drawings
Fig. 1 is the structured flowchart of the digital communication apparatus of the mass flowmenter in the embodiment of the present invention one；
Fig. 2 is the flow chart of the digital communication method of the mass flowmenter in the embodiment of the present invention two；
Fig. 3 is the system block diagram of the mass flowmenter in the embodiment of the present invention three；
Fig. 4 is the schematic diagram of the A5191HRT cake cores in the embodiment of the present invention three；
Fig. 5 is the schematic diagram of the AD421 cake cores in the embodiment of the present invention three；
Fig. 6 is the schematic diagram of filter circuit in the embodiment of the present invention three and power supply selection circuit.
Embodiment
The present invention is described in further detail with reference to the accompanying drawings and examples.It is understood that this place is retouchedThe specific embodiment stated is used only for explaining the present invention, rather than limitation of the invention.It also should be noted that, in order to justPart related to the present invention rather than entire infrastructure are illustrate only in description, accompanying drawing.
Embodiment one
Fig. 1 is the structured flowchart of the digital communication apparatus for the mass flowmenter that the embodiment of the present invention one is provided, the present embodimentBe applicable to transmit while the multiple parameter variables of mass flowmenter, can on a cable simultaneous transmission analog signal and foldedData signal thereon is added in, both do not interfere with each other.The digital communication apparatus may be mounted in the transmitter of mass flowmenter.As shown in figure 1, the digital communication apparatus can specifically include：Microprocessor 110, HART modem 120 and digital-to-analogue conversionDevice 130, is illustrated to its 26S Proteasome Structure and Function below.
Microprocessor 110, is connected to digital analog converter 130 and HART modem 120, for digital analog converter130 send the first data, and send the second data to HART modem 120；
Wherein, the first data can be differed with the second data, and the first data can be set as required transmissionMajor parameter, such as mass flow parameter, the second data can be set as the other parameters of required transmission, and such as volume flow is joinedNumber, temperature parameter, density parameter etc..In addition, above-mentioned first data and the second data can be carried out in digital voltage signal formData transfer.
HART modem 120, is connected to digital analog converter 130, for being modulated to the second data, turns to digital-to-analogueParallel operation 130 sends the signal after modulation；
Wherein, specific modulated process is：HART modem 120 receives the second data that microprocessor 110 is sent, warpOvennodulation device is modulated to fsk signal, i.e., represent logical one with " 1200Hz ", and " 2200Hz " represents logical zero, afterwards by rippleShape shaping circuit exports satisfactory signal, and the effect of waveform shaping circuit here is to make fsk signal meet signal waveformThe requirement of rising edge and trailing edge, this is due to that shallower rising edge and trailing edge waveform can reduce the string with other signalsDisturb.
Digital analog converter 130, for handling the first data, obtains analog current signal, superposition output simulation electricityFlow the signal after signal and modulation.
Wherein, if the first data are transmitted in digital voltage signal form, concrete processing procedure is：First data are firstAnalog voltage signal first is converted into through D/A converting circuit, then above-mentioned analog voltage signal turns through voltage-current converter circuit againChange analog current signal into.In addition, the first data can also be transmitted in digital current signal form, it is corresponding specific treatedJourney can be changed, and the first data are converted into analog current signal through D/A converting circuit.Analog current signal can be 4~20mA signals.
Above-mentioned described superposition is specifically referred to：It is to refer to fsk signal based on the signal after modulation, it is the amplitude of Phase ContinuationFor ± 0.5mA sinusoidal modulation wave signal, in a cycle, the average value of fsk signal is 0, thus its do not interfere with it is above-mentionedThe transmission of analog current signal, i.e. analog current signal and fsk signal can be with simultaneous transmission and this principles that is independent of each other, directlyBy the output end of the signal output after modulation to digital analog converter 130, wherein, digital analog converter 130 is without any processing to its.
The technical scheme of the present embodiment, the number after being modulated is modulated to parametric variable by HART modemWord signal, digital analog converter handles parametric variable progress and obtains analog current signal, digital analog converter superposition output simulation electricityThe data signal after signal and modulation is flowed, single parameter variable can only be exported by solving existing mass flowmenter, it is impossible to meet manyThe problem of parameter exports demand, can realize that multi-parameter is transmitted while compatible conventional analog systems using digital communication,Superposed transmission analog signal and data signal on one cable, both do not interfere with each other.In addition, using superposition output, without newLink connection, is transformed simple and convenient so that the Reconstruction in field cost of existing mass flowmenter is relatively low.It can wherein be passed by analog signalDefeated main parameter, digital data transmission other parameters.
In addition, after analog current signal is obtained, digital analog converter 130 can individually export the analog current signal.I.e. above-mentioned digital communication apparatus can individually perform existing single parameter variable output, can also be superimposed output multi-parameter and becomeAmount.
In addition, HART modem 120 may also connect to host computer, the control letter for receiving host computer transmissionNumber, the control signal is demodulated, the signal after demodulation is sent to microprocessor 110, wherein control signal is used to indicateSecond data of required acquisition.
Wherein, specific demodulating process is：Transmitted after the above-mentioned received bandwidth-limited circuit of control signal, carrier detecting circuitTo demodulator input, wherein carrier detecting circuit is used to determine whether demodulator input has the effective fsk signal of amplitude,Demodulated device exports the data signal of corresponding control signal.The two-way biography of data signal can be realized by HART modemIt is defeated, meanwhile, communicated using HART relative to other communication modes, transmission range is farther, up to 500m.
HART modem 120 can be that HART modem 120 provides power supply with external power supply chip.
On the basis of above-mentioned technical proposal, digital communication apparatus can also include：Filter circuit, the input of filter circuitEnd is connected to the output end of digital analog converter 130, for filtering out the electromagnetic interference signal in above-mentioned digital communication apparatus so that matterThe communication of amount flowmeter is effectively stably carried out.The output end of the filter circuit as digital analog converter 130 final output end.
On the basis of above-mentioned technical proposal, it is preferred that digital communication apparatus can also include：Power supply and power supply are openedClose.Power supply is connected to digital analog converter 130, under the control of power control switch, being powered to digital analog converter 130；ElectricitySource controlling switch, is connected to above-mentioned power supply, for controlling being turned on and off for the power supply.For example, can be connect in current loopEnter 24V power supplys.
This preferred embodiment adds two kinds of optional functions of the active output of electric current and the passive output of electric current, and user can be withActive passive function is switched by power control switch (can be hardware switch), user closes power control switch, i.e., activeThe situation of output, the power supply of digital analog converter is provided by transmitter；User's power-on controlling switch, i.e., the feelings of passive outputCondition, the 24V power supplys accessed in current loop are to loop service.User can utilize power control switch according to field conditionOpening and closing, two kinds of way of outputs of free switching.
Certainly, the digital communication apparatus of the present embodiment can include filter circuit, power supply and power control switch simultaneously.
On the basis of above-mentioned technical proposal, host computer can be also used for receiving the information of user's input, according to the informationAdjust the capacitance of the output end of digital analog converter 130 so that the signal after modulation meets preparatory condition.Wherein, preparatory condition bagIncluding makes suitable, stable output signal of signal waveform amplitude size of output etc..Signal is adjusted using the electric capacity in circuit,The interference free performance of signal that can be after enhanced modulation.
Embodiment two
Fig. 2 is the flow chart of the digital communication method for the mass flowmenter that the embodiment of the present invention two is provided, and this method can be byThe digital communication apparatus of embodiment one is performed, and this method is specifically included：
Step S210, digital analog converter receive the first data that microprocessor is sent, and first data are handled, obtainedTo analog current signal；
Step S220, digital analog converter receive the signal after the modulation that HART modem is sent, wherein after modulationSignal is that the HART modem is modulated to the second data that microprocessor is sent and obtained；
Step S230, digital analog converter superposition export the signal after above-mentioned analog current signal and above-mentioned modulation.
The technical scheme of the present embodiment, the number after being modulated is modulated to parametric variable by HART modemWord signal, digital analog converter handles parametric variable progress and obtains analog current signal, digital analog converter superposition output simulation electricityThe data signal after signal and modulation is flowed, single parameter variable can only be exported by solving existing mass flowmenter, it is impossible to meet manyThe problem of parameter exports demand, can realize that multi-parameter is transmitted while compatible conventional analog systems using digital communication,Superposed transmission analog signal and data signal on one cable, both do not interfere with each other.In addition, using superposition output, without newLink connection, is transformed simple and convenient so that the Reconstruction in field cost of existing mass flowmenter is relatively low.It can wherein be passed by analog signalDefeated main parameter, the effect of digital data transmission other parameters.
Further, before step S220, this method also includes：
HART modem receives the control signal that host computer is sent, and the wherein control signal is used to indicate required acquisitionThe second data；
HART modem is demodulated to above-mentioned control signal；
HART modem sends the signal after demodulation to microprocessor.
As can be seen here, the transmitted in both directions of data signal can be realized by HART modem, meanwhile, entered using HARTRow communication is relative to other communication modes, and transmission range is farther, up to 500m.
Further, after step S210, this method can also include：Digital analog converter individually exports the analog currentSignal.I.e. above-mentioned digital communication method can individually perform existing single parameter variable output, can also be superimposed many ginsengs of outputNumber variable
On the basis of above-mentioned technical proposal, before step S230, this method can also include：Filtered by filter circuitExcept the electromagnetic interference signal in digital communication apparatus so that the communication of mass flowmenter is effectively stably carried out.
On the basis of above-mentioned technical proposal, before step S230, this method can also include：Host computer receives userThe information of input, the capacitance of digital analog converter output end is adjusted according to the information so that the signal after modulation meets default barPart.Wherein, preparatory condition includes making suitable, stable output signal of signal waveform amplitude size of output etc..Using in circuitElectric capacity is adjusted to signal, the interference free performance of signal that can be after enhanced modulation.
Embodiment three
Fig. 3 is the system block diagram for the mass flowmenter that the embodiment of the present invention three is provided, on the basis of the various embodiments described above,The present embodiment provides a kind of Coriolis force mass flowmenter that digital communication is carried out using above-mentioned digital communication apparatus.
As shown in figure 3, the mass flowmenter includes sensing system 310 and transducer system 320, both are by connecting electricityCable 330 carries out data transmission.Transducer system 320 includes：Guard grating 3201, detection circuit 3202, drive circuit 3203, temperatureMeasuring circuit 3204, ferroelectric memory 3205, microprocessor 3206, keyboard 3207, analog output circuit 3208, digital communication mouldBlock 3209 and liquid crystal display 3210, wherein, analog output circuit 3208 equivalent to the digital analog converter described in embodiment one,Digital communications module 3209 equivalent to the HART modem 120 described in embodiment one, above-mentioned analog output circuit 3208,Digital communications module 3209 and microprocessor 3206 constitute the digital communication apparatus described in embodiment one, in addition, pick-upMiscellaneous part is existing part in mass flowmenter in device system 320, the embodiment of the present invention to its concrete structure and function notIt is described in detail.
Sensing system 310 is mainly used in the data such as measurement phase, temperature, and drive circuit 3203 sends drive signal toDriving coil 3103, opens whole measurement pipe and shakes, when there is fluid to flow through measurement pipe, and left coil 3102 and right coil 3101 can be withThe phase difference of two measurement pipes is detected, phase signal is transmitted to transducer system 320,320 pairs of collections of transducer systemPhase signal, temperature signal carry out calculating processing, and output drive signal, while obtaining flow information, density information etc..SpecificallyMeasurement procedure, calculate handling process and measuring principle dawn known to those skilled in the art, the present embodiment to this withoutDescribe in detail.
The digital communication apparatus that lower mask body is constituted using A5191HRT cake cores, AD421 cake cores and microprocessor 110 asExample is introduced.
Fig. 4 is the schematic diagram of A5191HRT cake cores, and Fig. 5 is the schematic diagram of AD421 cake cores, and the present embodiment is only to above-mentionedThe pin related to digital communication process is illustrated in chip, and the function of other pins and connection may refer to correspondence chipOperation instructions, the present invention is to this without describing in detail.
The general serial transceiver module UART of A5191HRT cake cores and microprocessor interface signal is detected including carrier waveOCD, HART demodulation output ORXD, HART modulation input ITXD, request send INRTS, pass through OTXA pins and AD421 cake coresC3 pins connection.Interface for digital communication clock line CLOCK, the data wire DATA of AD421 cake cores and latch line LATCH with it is micro-The serial communication interface of processor is joined directly together, and C1, C2 and C3 are filter capacitor, are connected with pottery between publicly COM respectivelyPorcelain electric capacity C31, C29 and C30.A5191HRT cake cores can provide power supply with external power supply chip for A5191HRT cake cores.
AD421 major functions are that driving current signal is externally exported, especially by clock line CLOCK, data wire DATA andLatch line LATCH and receive the first data that microprocessor is sent, the data are handled, analog current signal is obtained.
A5191HRT modulation and demodulation processes are specially：When it is high level that request, which sends INRTS, demodulated in A5191HRTDevice is worked, and modulator is closed, and A5191HRT receives the control signal that microprocessor is sent, and control signal passes through bandpass filtering electricityAfter road, amplified waveform circuit, incoming carrier detection circuit when detecting effective fsk signal, makes OCD export low level, enteredDemodulator, " 1 " is demodulated into by 1200Hz signal, and 2200Hz signals are demodulated into " 0 ", and through A5191HRT demodulation outputs ORXDMicroprocessor is transferred to, microprocessor receives command frame and makees corresponding data processing, then passes through data processing and produces and to send outThe data signal of the acknowledgement frame returned, i.e. the second data；When it is low level that request, which sends INRTS, modulator work in A5191HRTMake, demodulator is closed, A5191HRT receives the data signal that microprocessor is sent to ITXD, is modulated into after fsk signal, through waveformShaping circuit is exported by OTXA, is capacitively coupled to AD421 output end, is transmitted on the analog current signal that is then added to,So far sending and receiving for data signal is completed.
The Coriolis force mass flowmenter of digital communication is carried out using above-mentioned digital communication apparatus, can be in compatible traditionWhile simulation system, realize that multi-parameter is transmitted using digital communication, the superposed transmission analog signal sum on a cableWord signal, both do not interfere with each other.In addition, using superposition output, without new link connection, transforming simple and convenient so that existing qualityThe Reconstruction in field cost of flowmeter is relatively low.The transmitted in both directions of data signal can be realized by HART modem, is passed simultaneouslyIt is defeated distant.
Furthermore, it is possible to by adjusting electric capacity C31, C29 and C30, make the signal amplitude size that A5191HRT is exported more closeSuitable, output signal is more stable.It is experimentally confirmed, after adjustment electric capacity, the signal of output is stronger, allows model in HART protocolIn enclosing, its interference free performance is added.
Fig. 6 shows filter circuit, the power supply selection circuit of active passive and AD421 connection, as shown in fig. 6, filteringCircuit specifically includes F2, D3, L2, C8 etc., and the input of filter circuit is connected to AD421 output end, the output of filter circuitEnd is used to filter out the electromagnetic interference signal entered in digital communication apparatus as output end final AD421, filter circuit.ForElectric selection circuit is connected to AD421 output end (being herein the output end of filter circuit), for the control in power control switchPowered under system to AD421, user can control to be turned on and off 24V power supply by power control switch, so facilitate userAccording to field condition, the active output of free switching electric current and passive both modes of output of electric current.
Note, above are only presently preferred embodiments of the present invention and institute's application technology principle.It will be appreciated by those skilled in the art thatThe invention is not restricted to specific embodiment described here, can carry out for a person skilled in the art it is various it is obvious change,Readjust and substitute without departing from protection scope of the present invention.Therefore, although the present invention is carried out by above exampleIt is described in further detail, but the present invention is not limited only to above example, without departing from the inventive concept, alsoOther more equivalent embodiments can be included, and the scope of the present invention is determined by scope of the appended claims.