1、 Flow meter circuit parameters

Power supply: external power12~24VDC/30mA(-20%~+15%)；Internal electricity3V6The lithium battery automatically switches between the two.

（1）Three lines4~20mALinear correction current output（IoutgiveGNDCircuit load≤600time）.

（2）Programmable pulse output: High level ≥5V(Supply voltage)-1V）； Low Level<0.5V; Including3KPull up the resistor to open the output.

（3）Temperature measurement supportPt100andPt1000Software selection.

（4）Pressure measurement support3KThe following silicon piezoresistive pressure sensors and4-20mASelection of jumper wires for pressure transmitters.

（5）Communication supportMODBUS-RTUprotocol485communication.

2、 Circuit Description

VT3WThree line system, new third generationvortex streetThe flow meter circuit has a signal measurement circuit divided intoMSPTwo types of mixed digital signal processing and improved classical analog amplification and filtering circuits are used to cope with various complex on-site environments.

(1)MSPHybrid adaptive digital signal processing front-end circuit:

Adopting a streamlined and efficient low-power new digital signal processing circuit, after years of research and improvement, we have abandoned the second-generation pure software filtering processing scheme that is difficult to solve the lower bound irregular waves.Creatively utilizing front-end pre-processing hardware with adjustable charge matching amplification, adjustable gain transformation, and fine partition filtering,Window function andFFTPerform time-domain and frequency-domain diversification software processing using wavelet signal theory such as spectrum analysis. The concept of partition restrictionsanswerA/DConvert the collected vortex street signalsMSP-Mixed digital signal processing, using16Interval limited filteringIt has been better resolved due toUncertainty of flow medium density and viscositySexual induced vortex circuit operationThe significant deviation in frequency causes the filtering frequency band to be inconsistent with the on-site work, leading to the problem of significant measurement distortion.And created a unique creation byFlow waveform analysis for determining measurement lower limit through waveform matching and signal-to-noise ratioConcept, for the long-term troubled vortex flowmeterPoor seismic resistance, unstable lower limit, resistant50HzPoor electromagnetic interference, etcThe problem has arisenSignificant improvementCan beAccurate setting of working parametersMixed processing of hardware and software, mixed calculation of time and frequency domains, and output frequency corresponding to the flow rateIt can accurately measure the flow rates of gases, liquids, and vapors over a wide range of flow rates.

（2） Improved classic analog amplification filtering front-end circuit:

The new analog amplification filtering front-end circuit increases the input impedance, thereby reducing waveform distortion at the low-frequency end. supportK1Simplify to6Position by,press1-2-5-10The admission rate has been readjustedK2andK3Filter capacitor parametersTake care of bothDN15-20Make it rightDN25The following small-diameter gas measurements have better applicability. But yesDN350The above filtering is slightly weakened. at the same timeK2andK3Symmetry is beneficial for synchronous adjustment. Improved the pulse output circuit, which has a certain degree of adaptability to high frequency and output driving. Added filtering and protection to the power input section, improving reliability and resistance to power noise interference.

（3） Two unified flow calculation display circuits:

MSPBoth digital and analog models use the same backend wiring board (the two amplification display processing circuits are interchangeable). Can be translated in Chinese/English prompt: Select the software menu to adapt to various calibers and measurement medium sections (only applicable)MSPType). After data processing, it is processed byLCD12864lcd. The signal remote transmission circuit can use a three wire system4-20mAoutputelectric currentSignal. There is also a versatile programmable pulse output signal that can be programmed into various output modes. Also available for pairingMODBUS485-RTUCommunication.

1） Pulse output mode:

A、 Signal frequency output: Directly output the frequency of the probe detection signal in real time, usually used for instrument calibration.

B、 Correction frequency output: the output of real-time monitoring signals corrected according to the flow coefficient

C、 Frequency output: Output the converted frequency, and the frequency value is output according to the full flow rate1000HzLinear calculation.

D、 Pulse output: Output converted pulses, and the number of pulses is calculated by dividing the cumulative flow rate of each calculation cycle by the pulse equivalent. Only output is allowed for each calculation cycle1000If the actual number of pulses within the calculation period is greater than one pulse1000If one, it will automatically accumulate and output to the next calculation cycle; Each small cycle only allows output4If the actual number of pulses within the calculation period is insufficient, the pulse count will be one pulse4If there are one pulse, it will automatically accumulate and output to the next calculation cycle; The effective level of the output pulse is high. pourMeaning: Engineers need to set appropriate pulse equivalent factors based on the current applicable object.

E、 Upper limit alarm output—When the alarm flow exceeds the set alarm output, the output transistor will conduct to ground at a low level during the alarm; When not in alarm mode, the output transistor is turned off, and the pull-up resistor causes the terminal to be at a high level.

F、 Lower limit alarm output—Output an alarm below the set alarm flow rate, and when the alarm occurs, the output transistor will conduct to ground at a low level; When not in alarm mode, the output transistor is turned off, and the pull-up resistor causes the terminal to be at a high level.

2） Current output:

The current output is linear4-20mAThe output range is[4-22.4]mAWhen the instantaneous flow rate is less than or equal to the lower cut-off flow rate, or the signal frequency is0When, output4mAelectric current. In other cases, the current is output according to the cut-off flow rate4mAFull flow output20mALinearly calculate the output current value, if the calculated current value exceeds22.4mA,The highest output22.4mA.

3） ModbusCommunication function:

The transmitter supportsModbusof4800and9600Baud rate communication, throughModbus-RTUprotocol3The command (read and hold register) dynamically reads various parameters of the instrument running in real-time, with a response time of50mSWithin;ModbusMinimum interval between consecutive commands100mS；

4） Usage environment:

Due to different environmental temperatures,LCDThe display response speed of the screen also changes, and if it is at low temperaturesLCDA fast refresh rate can cause unclear display. Use the "Environmental Temperature" option in the Engineer menu to set the selectionLCDThe refresh rate of the screen is-20℃Can be used in low-temperature environments.

5） Frequency band selection:

According to the frequency range division of vortex signals16The frequency bands are:1.6-45Hz、2.4-65Hz、3.6-90Hz、4.8-120Hz、6.4-160Hz、8.8-220Hz、11-275Hz、14-350Hz、18-450Hz、22-550Hz、28-700Hz、34-850Hz、42-1050Hz、52-1300Hz、64-1600Hz、96-2400HzUsers can set the appropriate frequency band in the engineer menu based on the intended use of the transmitter. Note that if the frequency band setting does not match the signal object, the transmitter will not function properly.

6） instrumentMSPParameter setting menu class:

existMSPIn the settings menu, you can set the signal input capacitance, gain, signal cut-off peak to peak voltage50Hz

Cut off switch, strong anti-interference mode, signal filtering and other mode parameters; Correctly set upMSPBeneficial and improved parameters

Instrument performance, incorrectMSPParameter settings can reduce instrument performance. soMSPThe items in the settings menu must be

Only professionals are allowed to operate!

Flow meter working interface

The working interface of the flowmeter includes two interfaces, one is the main interface and the other is the auxiliary interface. As shown in the picture:

chart 1Main work interface

Signal comparison mode:

l L=Low Zone0-1/4

l H=high area1/4-1/2

l S=narrow=denoise5%

l M=centre=denoise10%

l W=wide=denoise15%

l N=deny=close

The "plug" pattern displayed in the power supply mode indicates that the current power supply is from the power source; Display the "battery" pattern to indicate the current battery power supply

equalTTemperature andPThe pressure is displayed as“=”When indicates that the current temperature and pressure are measured values;

equalTTemperature andPWhen the pressure is displayed as "≡" after it, it indicates that the current temperature and pressure measurement have exceeded the limit, and the default is used

Set the value, pay attention to checking if the sensor is abnormal at this time!

equalTThe identity of temperature is“Tu≡ "indicates that the measured temperature exceeds500The upper limit of the temperature is fixed at the setting value of "default temperature" in the engineer menu.

equalTThe identity of temperature is“Td≡ "indicates that the measured temperature exceeds-200The lower limit of the temperature is set to the "default temperature" value in the engineer menu.

equalPThe identity of pressure is“Pd≡ "indicates that the measured pressure is lower than-101.3kPaAt this time, the pressure is fixed to the setting value of "default pressure" in the engineer menu.

equalPThe identity of pressure is“Pu≡ "indicates that the measured pressure exceeds the upper limit by one time of the range (the range is the difference between the upper pressure limit and the lower pressure limit). At this time, the pressure is fixed to the set value of" default pressure "in the engineer menu.

equalTTemperature orPWhen the pressure is followed by "≈", it indicates that the displayed temperature or pressure is the reverse calculation value of steam.

chart 2Auxiliary work interface

In the auxiliary interface, different names in the signal frequency row represent different operating states

² Fin—Normal signal frequency

² FinCV—The signal amplitude is weak and the output is cut off. At this time, the flow rate is not calculated

² FinC5—The signal belongs to50HzNoise, output is cut off, flow rate is not calculated at this time

² FinFL—The signal is below the frequency range, and the output is cut off. At this time, the flow rate is not calculated

² FinFH—The signal is higher than the frequency range, and the output is cut off. At this time, the flow rate is not calculated

² FinSL—The signal wavenumber is too low, the output is cut off, and the flow rate is not calculated at this time

² FinSM—The signal wave is too chaotic and the output is cut off. At this time, the flow rate is not calculated

² FinCS—The signal characteristics belong to noise, and the output is cut off. At this time, the flow rate is not calculated

In the auxiliary interface, different names in the output frequency row represent different output states

u F_bas—Basic signal output, i.e. output according to the measured signal frequency

u F_adj—Calibrate output by multiple pointsKFor detailed algorithms of value correction output, please refer to the following chapters

u F_out—Frequency output, based on the measured signal, calculates and outputs a signal of a certain frequency.

signal frequency=Instantaneous flow rate * 1000 / Full flow rate （Hz）

u Pulse—Pulse output, the number of output pulses calculated based on the "Pulse Factor" in the menu

u H-AL=0—High alarm not generated

u L-AL=0—Low alarm not generated

u H-AL=1—High alarm generated

u L-AL=1—Low alarm generated

u NO—The current output is invalid

In the auxiliary interface, the output current value is the actual output current value in the power supply mode; Fixed display in battery powered mode0.0(Because there is no current output at this time)

The main interface and auxiliary interface are connected by pressing‘+/S’LeftKeys and‘’RightKey switching.

Left click for+And flip down the page,Long press forSexit. Right click for<And flip up the page,Long press forEEnter and confirm.

Long press on the auxiliary interface‘’Left click to enter password input mode. Users can press continuously‘+/S’Press the key to select the password number that needs to be entered for the current input position, and then press‘’Press the key to move and input the cursor position. When I finish losing2After entering the password, long press‘’Enter the function settings menu corresponding to the password; Long press while in password input mode‘+/S’Press the key to return to the auxiliary interface and continue updating the displayed measurement values.

Regarding the refresh speed of the main and auxiliary work interfaces. In the engineer menu, there is a "ambient temperature" setting option,In the power supply mode,ifselect-10℃When,1.2Refresh once per secondIfselect-20℃，8Refresh once per second；In battery powered mode,4Refresh every second.