CN103954652B - A kind of Intelligent methane all range sensor and full scale methane concentration measuring method thereof - Google Patents

Abstract

The invention discloses a kind of Intelligent methane all range sensor and full scale methane concentration measuring method thereof, its Intelligent methane all range sensor includes four line sockets, bridge-operative power supply, light current circuit power, communication interface circuit, methane bridge-operative circuit, single chip circuit and ambient temperature measurement circuit, two power lines of four line sockets connect bridge-operative power supply, and light current circuit power connects bridge-operative power supply；Two order wires of four line sockets are I²C order wire, and connect communication interface circuit, communication interface circuit connects single chip circuit, and the single-chip microcomputer STM32L151C8 of single chip circuit includes eeprom memory, for running parameter and the I of setting of storage sensor²C address, single chip microcomputer is integrated with required DAC, ADC and I²C peripheral hardware；Methane bridge-operative circuit and ambient temperature measurement circuit connect single chip circuit respectively.This Intelligent methane all range sensor can realize gamut and measure methane concentration, it is not necessary to carries out straightened up in place, is I with the communication interface of external connection²C interface, easy to use.

Description

A kind of Intelligent methane all range sensor and full scale methane concentration measuring method thereof

Technical field

The present invention relates to the technical field of intelligence sensor, refer in particular to a kind of Intelligent methane all range sensor And full scale methane concentration measuring method.

Background technology

The measurement of methane concentration is extremely important for coal and petrochemical industry, and metering system currently mainly is to urge Change combustion method.The detecting element of catalysis burning is connected by the black element of platinum resistance and the white element of platinum resistance, black unit Part surface contains catalyst, after by electrical heating detecting element being heated to the high temperature of about 400 DEG C, if black element Around containing methane gas, then methane can occur flameless catalytic combustion, and releases heat, and this heat can make black The resistance value of element raises further.The size that black element resistance rises is proportional with the concentration of methane, passes through The change measuring resistance value i.e. can determine that gas concentration.But, when gas concentration reaches more than 4%, measure Deterioration in accuracy, and easily spontaneous combustion, burn out whole sensor.Catalytic combustion method is only suitable for methane concentration and exists Measure in the range of 0%～4%.

In order to reach full scale methane measurement of concetration, people are thermal conductivity measuring method and catalytic combustion method Combine, on the basis of catalysis burning, increase heat-conduction component, utilize methane concentration and the coefficient of heat conduction in just The relation of ratio measures the methane gas of high concentration (4%～100%).In catalysis unit during combination sensor work Switching between part and heat-conduction component, this quadrat method can partly solve gamut and measure problem, but also deposits , even there is diadic question, simultaneously because do not urge in the smooth transition problem when two kinds of measuring cells are in switching Change the temperature control mechanism of the black element that burns, the temperature or higher when catalysis burning, shorten whole sensing The service life of device.Additionally, general methane analog sensor need with special transmitter with the use of, do not carry For general Interface for digital communication.

Summary of the invention

It is an object of the invention to overcome the deficiencies in the prior art and shortcoming, it is provided that a kind of intelligence the most reliably Methane all range sensor and full scale methane concentration measuring method thereof, utilize methane catalytic combustion sensor to hold concurrently As thermal conductivity sensors, it is respectively directed to its conduction of heat mode of operation and catalysis burner's operation mode sets up two Temperature operating point, carrys out stable detection element manipulation point temperature by the running voltage changing electric bridge.

For achieving the above object, its Intelligent methane all range sensor of technical scheme provided by the present invention, bag Four line sockets, bridge-operative power supply, light current circuit power, communication interface circuit, methane bridge-operative are included Circuit, single chip circuit and for calculating the methane detection element ambient temperature relative to ambient temperature temperature rise Measuring circuit, wherein, two power lines of described four line sockets connect bridge-operative power supply, by described electric bridge Working power provides the working power of 3.6V, works for bridge circuit, simultaneously also in addition to bridge circuit Light current circuit power power, described light current circuit power connect bridge-operative power supply；Described four line sockets Two order wires are I²C order wire, and connect communication interface circuit, it is dynamo-electric that described communication interface circuit connects monolithic Road, the single-chip microcomputer STM32L151C8 of described single chip circuit includes eeprom memory, is used for storing The running parameter of sensor and the I of setting²C address, single chip microcomputer is integrated with required DAC, ADC and I²C peripheral hardware；Described methane bridge-operative circuit and ambient temperature measurement circuit connect single chip circuit respectively.

Described methane bridge-operative circuit selects methane catalytic combustion sensor MJC4/3.0L, includes field effect Pipe, amplifier, NPN audion, the first resistance, the second resistance, the 3rd resistance, the 4th resistance, the 5th Resistance, the 6th resistance, the 7th resistance；Wherein, described methane catalytic combustion sensor MJC4/3.0L's is black Element is the platinum resistance of band catalyst, and its white element is the platinum resistance without catalyst；Described field effect transistor Grid connects the I/O switching signal output of single-chip microcomputer STM32L151C8, and its drain electrode connects bridge-operative power supply, by Described bridge-operative power supply provides the working power of 3.6V, and described field effect transistor is parallel with the first resistance；Described Amplifier, NPN audion and the second resistor group success rate are amplified and voltage follower circuit, described amplifier In-phase input end connects the DAC output of single-chip microcomputer STM32L151C8；Described 3rd resistance, the 4th resistance, Black element, white element and the 5th resistance composition one electric bridge, described black element, the 6th resistance, white element and 7th resistance forms another electric bridge.

Described bridge-operative power supply and light current circuit power be respectively adopted LDO power supply chip SPX1117 and SPX3819, reference power source uses REF3020, and described reference power source connects single-chip microcomputer STM32L151C8's ADC pin, and use the method for comparison to correct the measured value of other analog input signal.

Described communication interface circuit is by the I of single-chip microcomputer STM32L151C8²C pin, pull-up resistor and ESD Chip PRTR5V0U2X forms.

Described ambient temperature measurement circuit uses DS18B20 to measure ambient temperature.

Full scale methane concentration measuring method of the present invention, as follows:

After powering on, Intelligent methane all range sensor carries out system initialization, outside on I/O initialization and sheet If initializing, peripheral hardware initializes and includes ADC, DAC and I²C initializes, distribution provisional communication relief area, Reception data buffer, starts I²C receives interruption, and to arrange duty be conduction of heat duty；Then Judge current duty, if conduction of heat duty, then being in series by black element and white element Measuring cell temperature control at 200 DEG C, otherwise enter catalysis burning duty, black component temperature is controlled At about 400 DEG C；In conduction of heat duty, measure voltage by heat-conduction principle and calculate methane concentration, so After carry out concentration judgement, if concentration is less than 3.5%, then proceeds to catalysis burning duty, the most directly carry out I²C communication process；In catalysis burning duty, measure voltage by principle of catalyst combustion and calculate methane concentration, Then carry out methane concentration judgement, if concentration is more than 4%, is then operated state transfer, proceeds to conduction of heat work Make state, so circulate.

When being in conduction of heat duty, single-chip microcomputer STM32L151C8 exported by DAC change defeated Enter the HeatVoltage voltage of the in-phase input end of amplifier, to black element and white power elements, it is carried out Being heated and maintained at 200 DEG C, the phasing meter of platinum resistance is saved in the Flash of single-chip microcomputer STM32L151C8, Can not revise, methane concentration can be calculated when thermal balance according to following formula (1):

${\mathrm{\α}}_{CH4}=312.5(\frac{P-P_0}{k(T_d-T_0)}-1)---\left(1\right)$

In formula, α_CH4For methane concentration, P is the electrical power that detecting element consumes, following formula (2) calculate, T_dFor measuring cell temperature, T₀For ambient temperature, measure DS18B20, P₀With k it is and Intelligent methane The parameter that all range sensor structure is relevant, by test determination, is saved in single-chip microcomputer STM32L151C8 EEPROM in；

$P=\frac{{V_1}^2}{RTb+RTw}---\left(2\right)$

When being in catalysis burning duty, single-chip microcomputer STM32L151C8 is exported by DAC and changes The HeatVoltage voltage of the in-phase input end of input amplifier, to black element and white power elements, enters it Row is heated and maintained at 400 DEG C, then methane occurs catalyst combustion reaction on black element, releases heat and makes black unit The temperature of part raises, the resistance of the most black element by higher than the resistance of white element, the resistance of black element and white element Difference is proportional with methane concentration, obtains black element and the numerical value of white element accordingly by following formula (3), by following formula (4) resistance is obtained poor；

$\{\begin{array}{c}\begin{array}{cc}{V}_0=2V_2,& V_1=2V_3\end{array}\\ \frac{V_0}{R311+RTb+RTw}(RTb+RTw)=V_1\\ \frac{V_0}{R311+RTb+RTw}RTw=V_4\end{array}---\left(3\right)$

Δ RT=RTb-RTw (4)

In formula, R311 is the 3rd resistance, and RTb is black element；RTw is white element；Δ RT is black element RTb Difference with white element RTw；V₀For by the 3rd resistance R311, the 4th resistance R312, RTb+RTw and the 5th The running voltage of resistance R313 composition electric bridge；V₂It is the output of the 5th resistance R313；V₁For RTb+RTw's Output, is RTb, RTw, the 6th resistance R314 and the work electricity of the 7th resistance R315 composition electric bridge simultaneously Pressure；V₃It is the output of the 7th resistance R315, V₄Output for white element RTw；

In EEPROM in single chip microcomputer, preserve the relation table of black-and-white component resistance difference and methane concentration, By the concentration that i.e. can get methane of tabling look-up.

Use I²C interrupts receiving data, interrupts the data after receiving and processes in communication module, router Complete the most in the module；I²The application layer data bag of C agreement by address, function number, variable name, variate-value and Check code forms；When Intelligent methane all range sensor does not the most carry out address initialization or needs again to set When putting address, can be in communication with by broadcast address, including carrying out address distribution, Intelligent methane full dose Journey sensor is saved in the address of distribution in the EEPROM of its single-chip microcomputer STM32L151C8, after power down Without again initializing；After the distribution of address, the Intelligent methane all range sensor with different address can connect It is connected into I²C Web vector graphic, transmitter can connect multiple has I²The dissimilar Intelligent methane of C interface is complete Range sensors.

The present invention compared with prior art, has the advantage that and beneficial effect:

1, compared with traditional analog sensor, this Intelligent methane all range sensor is made without on-the-spot school Just；

2, this Intelligent methane all range sensor is I with the communication interface of external connection²C interface, easy to use；

3, this Intelligent methane all range sensor is when realizing gamut and measuring methane concentration, it is ensured that conduction of heat The operating temperature of mode of operation and catalyst operation pattern is stable, and between mode of operation, conversion steadily, extends biography Sensor service life, it is to avoid natural phenomena and possible peril occur.

Accompanying drawing explanation

Fig. 1 is the structural representation of Intelligent methane all range sensor.

Fig. 2 is the methane bridge-operative circuit theory diagrams of Intelligent methane all range sensor.

Fig. 3 is the state machine diagram of Intelligent methane all range sensor.

Fig. 4 is the workflow diagram of Intelligent methane all range sensor.

Detailed description of the invention

Below in conjunction with specific embodiment, the invention will be further described.

As it is shown in figure 1, the Intelligent methane all range sensor described in the present embodiment, include four line sockets M100, bridge-operative power supply M101, light current circuit power M102, communication interface circuit M103, methane Bridge-operative circuit M104, single chip circuit M105 and be used for calculating methane detection element relative to environment The ambient temperature measurement circuit M106 of temperature temperature rise；Wherein, this Intelligent methane all range sensor passes through four lines Socket M100 is connected with outside use equipment (transmitter or controller)；Described four line socket M100's Two power lines connect bridge-operative power supply M101, provide 3.6V's by described bridge-operative power supply M101 Working power, works for bridge circuit, simultaneously also to the light current circuit power M102 in addition to bridge circuit Power supply, described light current circuit power M102 connects bridge-operative power supply M101；Described four line socket M100 Two order wires be I²C order wire, and connect communication interface circuit M103, described communication interface circuit M103 Connect single chip circuit M105, the single-chip microcomputer STM32L151C8 of described single chip circuit M105 to include Eeprom memory, for running parameter and the I of setting of storage sensor²C address, in single chip microcomputer It is integrated with required DAC, ADC and I²C peripheral hardware；Described bridge-operative power supply M101 and light current circuit electricity Source M102 is respectively adopted LDO power supply chip SPX1117 and SPX3819, and reference power source uses REF3020, Owing to the single-chip microcomputer STM32L151C8 used is without reference power source pin, therefore refers to power supply and connect single-chip microcomputer The ADC pin of STM32L151C8, and use the method for comparison to correct the survey of other analog input signal Value；Described communication interface circuit M103 is by the I of single-chip microcomputer STM32L151C8²C pin, pull-up resistor Form with ESD chip PRTR5V0U2X；Described methane bridge-operative circuit M104 and ambient temperature measurement Circuit M106 connects single chip circuit M105 respectively；Described ambient temperature measurement circuit M106 uses Ambient temperature is measured by DS18B20.

As in figure 2 it is shown, methane bridge-operative circuit M104 described in the present embodiment selects methane catalytic combustion sensing Device MJC4/3.0L, include field effect transistor Q301, amplifier U301A, NPN audion Q302, One resistance R301, the second resistance R302, the 3rd resistance R311, the 4th resistance R312, the 5th resistance R313, 6th resistance R314, the 7th resistance R315；Wherein, described methane catalytic combustion sensor MJC4/3.0L The platinum resistance that black element RTb is band catalyst, its white element RTw is the platinum resistance without catalyst；Institute The grid stating field effect transistor Q301 connects the I/O switching signal output of single-chip microcomputer STM32L151C8, its drain electrode Meet bridge-operative power supply M101, described bridge-operative power supply M101 the working power of 3.6V, institute are provided State field effect transistor Q301 and be parallel with the first resistance R301；Described amplifier U301A, NPN audion Q302 With the second resistance R302 composition power amplification and voltage follower circuit, the homophase of described amplifier U301A is defeated Enter to terminate the DAC output of single-chip microcomputer STM32L151C8；Described 3rd resistance R311, the 4th resistance R312, Black element RTb, white element RTw and the 5th resistance R313 one electric bridge of composition, described black element RTb, 6th resistance R314, white element RTw and the 7th resistance R315 form another electric bridge.MeasureSwitch The I/O switching signal exported for single-chip microcomputer STM32L151C8, when Chip Microcomputer A/D C needs measuring bridge defeated When going out voltage, arranging MeasureSwitch is low level, controls the conducting of field effect transistor Q301, and single-chip microcomputer leads to Cross ADC and measure V₂～V₄Value.After bridge output voltage has been measured, MeasureSwitch is set for high electricity Flat, turn off field effect transistor Q301, by NPN audion Q302 to detecting element black element RTb and white element RTw powers.HeatVoltage connects the DAC output of single-chip microcomputer, for controlling the running voltage of detecting element, Thus control the operating temperature of detecting element.3rd resistance R311 is 25 ohm, remaining the 4th resistance R312, the 5th resistance R313, the 6th resistance R314 and the 7th resistance R315 are 2000 ohm.Due to V₀ And V₁V may be therefore passed through beyond the optimum measurement scope of ADC₂～V₄Measurement calculate V₀With V₁.By bridge circuit and corresponding resistance parameter, black element RTb and Bai Yuan can be calculated by following formula (1) The resistance of part RTw, further according to conduction of heat or the measurement methane concentration principle of catalysis burning, i.e. can get methane Concentration.

$\{\begin{array}{c}\begin{array}{cc}{V}_0=2V_2,& V_1=2V_3\end{array}\\ \frac{V_0}{R311+RTb+RTw}(RTb+RTw)=V_1\\ \frac{V_0}{R311+RTb+RTw}RTw=V_4\end{array}---\left(1\right)$

When being in conduction of heat duty, single-chip microcomputer STM32L151C8 is exported by DAC and changes The voltage of HeatVoltage, powers to black element RTb and white element RTw, is heated and maintained at it T_d(about 200 DEG C), T_dConcrete numerical value obtain by looking into the resistance phasing meter of platinum resistance, the phasing meter of platinum resistance It is saved in the Flash of single-chip microcomputer, can not revise.Methane can be calculated according to following formula (2) when thermal balance Concentration.

${\mathrm{\α}}_{CH4}=312.5(\frac{P-P_0}{k(T_d-T_0)}-1)---\left(2\right)$

In formula, α_CH4For methane concentration, P is the electrical power that detecting element consumes, following formula (3) calculate, T_d For measuring cell temperature, T₀For ambient temperature, measure DS18B20, P₀It is complete with Intelligent methane with k The parameter that range sensors structure is relevant, by test at experimental determination, is saved in the EEPROM of single-chip microcomputer In.

$P=\frac{{V_1}^2}{RTb+RTw}---\left(3\right)$

When being in catalysis burning duty, single-chip microcomputer STM32L151C8 is exported by DAC and changes The voltage of HeatVoltage, powers to black element RTb and white element RTw, is heated and maintained at it T_r(about 400 DEG C), then there is catalyst combustion reaction in methane on black element, releases heat and makes the temperature of black element Degree raises, the resistance of the most black element by higher than the resistance of white element, the resistance difference of black element and white element and first Alkane concentration is proportional, can obtain black element and the numerical value of white element accordingly by above formula (1), following formula (4) obtain Poor to resistance.

Δ RT=RTb-RTw (4)

In EEPROM in single chip microcomputer, preserve the relation table of black-and-white component resistance difference and methane concentration, By the concentration that i.e. can get methane of tabling look-up.This relation table is on the basis of MJC4/3.0L sensing data handbook Determined by test.

As it is shown on figure 3, after Intelligent methane all range sensor powers on, be introduced into conduction of heat duty, it After conduction of heat duty and catalysis burning duty between change.When Intelligent methane all range sensor When being in conduction of heat duty, single-chip microcomputer controls the operating temperature of detecting element at T_d(about 200 DEG C), Measure methane concentration by heat-conduction principle, when concentration is less than 3.5%, then proceed to catalysis burning duty. In catalysis burning duty, it is T that Single-chip Controlling detects the operating point temperature of black element_r(about 400 DEG C), Measure methane concentration by principle of catalyst combustion, when concentration is more than 4.0%, the most again proceed to conduction of heat work shape State.

As shown in Figure 4, described Intelligent methane all range sensor realizes the concrete of full scale methane measurement of concetration Process is: M400 is that Intelligent methane all range sensor powers on, and after powering on, enters M401 and carries out system Initializing, initialize including I/O and On-Chip peripheral initializes, peripheral hardware initializes and includes ADC, DAC and I²C Initialize, distribute provisional communication relief area, reception data buffer, start I²C receives interruption, and arranges intelligence The duty of energy methane all range sensor is conducting operations state；Current intelligence is judged subsequently into M402 Energy methane all range sensor duty, if conduction of heat duty, then enters M403 measuring cell (black element and the series connection of white element) temperature controls at 200 DEG C；Otherwise enter catalysis burning duty, black Component temperature controls at about 400 DEG C.In conduction of heat duty, surveyed by heat-conduction principle in M404 Amount voltage calculates methane concentration, enters M405 afterwards and carries out concentration judgement, if concentration is less than 3.5%, then enters Enter M406 and proceed to catalysis burning duty, be otherwise directly entered M411 and carry out I²C communication process.Urging Change burning duty, in M408 by principle of catalyst combustion measure voltage calculate methane concentration, laggard Entering M409 and carry out methane concentration judgement, if concentration is more than 4%, enter in M410, the state of being operated turns Move, proceed to conduction of heat duty.After the communication module of M411, complete a program circulation, again enter Enter M402 and carry out next program circulation.

In order to ensure I²The real-time of C communication, uses I²C interrupts receiving data, interrupts the data after receiving and exists M411 communication module processes, and router completes the most in the module.I²The application layer data bag of C agreement It is made up of address, function number, variable name, variate-value and check code, as shown in table 1 below.

Table 1-application layer data bag

1 byte	1 byte	1 byte	4 bytes	N byte	2 bytes
						Address	Function number	Data length	Variable name	Variate-value	Check code

When Intelligent methane all range sensor does not the most carry out address initialization or needs to reset address Time, can be in communication with by broadcast address (broadcast address is 0), including carry out address distribution (be 2～ Address between 127), Intelligent methane all range sensor is saved in its single-chip microcomputer the address of distribution In EEPROM, without again initializing after power down.After the distribution of address, there is the Intelligent methane of different address All range sensor can connect into I²C Web vector graphic, transmitter can connect multiple has I²C interface Dissimilar Intelligent methane all range sensor.

Embodiment described above is only the preferred embodiments of the invention, not limits the enforcement model of the present invention with this Enclose, therefore the change that all shapes according to the present invention, principle are made, all should contain within the scope of the present invention.

Claims (8)

1. an Intelligent methane all range sensor, it is characterised in that: include four line sockets (M100), Bridge-operative power supply (M101), light current circuit power (M102), communication interface circuit (M103), methane Bridge-operative circuit (M104), single chip circuit (M105) and to be used for calculating methane detection element relative In the ambient temperature measurement circuit (M106) of ambient temperature temperature rise, wherein, described four line sockets (M100) Two power lines connect bridge-operative power supply (M101), by described bridge-operative power supply (M101) provide The running voltage of 3.6V, works for bridge circuit, the most also to the light current circuit electricity in addition to bridge circuit Source (M102) powers, and described light current circuit power (M102) connects bridge-operative power supply (M101)；Institute Two order wires stating four line sockets (M100) are I²C order wire, and connect communication interface circuit (M103), Described communication interface circuit (M103) connects single chip circuit (M105), described single chip circuit (M105) Single-chip microcomputer STM32L151C8 include eeprom memory, for storage sensor running parameter and The I set²C address, single chip microcomputer is integrated with required DAC, ADC and I²C peripheral hardware；Described methane Bridge-operative circuit (M104) and ambient temperature measurement circuit (M106) connect single chip circuit respectively (M105)。

A kind of Intelligent methane all range sensor the most according to claim 1, it is characterised in that: described Methane bridge-operative circuit (M104) selects methane catalytic combustion sensor MJC4/3.0L, includes field effect Should manage (Q301), amplifier (U301A), NPN audion (Q302), the first resistance (R301), Two resistance (R302), the 3rd resistance (R311), the 4th resistance (R312), the 5th resistance (R313), Six resistance (R314), the 7th resistance (R315)；Wherein, described methane catalytic combustion sensor MJC4/3.0L The platinum resistance that black element (RTb) is band catalyst, its white element (RTw) be without catalyst platinum electricity Resistance；The grid of described field effect transistor (Q301) connects the I/O switching signal output of single-chip microcomputer STM32L151C8, Its drain electrode connects bridge-operative power supply (M101), described bridge-operative power supply (M101) provide the work of 3.6V Making power supply, described field effect transistor (Q301) is parallel with the first resistance (R301)；Described amplifier (U301A), NPN audion (Q302) and the second resistance (R302) form power amplification and voltage follower circuit, described The in-phase input end of amplifier (U301A) connects the DAC output of single-chip microcomputer STM32L151C8；Described Three resistance (R311), the 4th resistance (R312), black element (RTb), white element (RTw) and the 5th electricity Resistance (R313) forms an electric bridge, described black element (RTb), the 6th resistance (R314), white element (RTw) Another electric bridge is formed with the 7th resistance (R315).

A kind of Intelligent methane all range sensor the most according to claim 1, it is characterised in that: described Bridge-operative power supply (M101) and light current circuit power (M102) are respectively adopted LDO power supply chip SPX1117 And SPX3819, reference power source uses REF3020, and described reference power source meets single-chip microcomputer STM32L151C8 ADC pin, and use the method for comparison to correct the measured value of other analog input signal.

A kind of Intelligent methane all range sensor the most according to claim 1, it is characterised in that: described Communication interface circuit (M103) is by the I of single-chip microcomputer STM32L151C8²C pin, pull-up resistor and ESD Chip PRTR5V0U2X forms.

A kind of Intelligent methane all range sensor the most according to claim 1, it is characterised in that: described Ambient temperature measurement circuit (M106) uses DS18B20 to measure ambient temperature.

6. the gamut first of the Intelligent methane all range sensor described in claim 1 to 5 any one Alkane concentration measuring method, it is characterised in that: after powering on, it is initial that Intelligent methane all range sensor carries out system Changing, initialize including I/O and On-Chip peripheral initializes, peripheral hardware initializes and includes ADC, DAC and I²At the beginning of C Beginningization, distributes provisional communication relief area, reception data buffer, starts I²C receives interruption, and arranges work State is conduction of heat duty；Then current duty is judged, if conduction of heat duty, then The measuring cell temperature being in series by black element and white element is controlled at 200 DEG C, otherwise enters catalysis burning Duty, controls black component temperature at 400 DEG C；In conduction of heat duty, surveyed by heat-conduction principle Amount voltage calculates methane concentration, then carries out concentration judgement, if concentration is less than 3.5%, then proceeds to catalysis burning Duty, the most directly carries out I²C communication process；In catalysis burning duty, burn former by catalysis Reason is measured voltage and is calculated methane concentration, then carries out methane concentration judgement, if concentration is more than 4%, then carries out work Make state transfer, proceed to conduction of heat duty, so circulate.

A kind of full scale methane concentration measuring method the most according to claim 6, it is characterised in that:

When being in conduction of heat duty, single-chip microcomputer STM32L151C8 exported by DAC change defeated Enter the Heat Voltage of the in-phase input end of amplifier, to black element and white power elements, it is heated And it being maintained at 200 DEG C, the phasing meter of platinum resistance is saved in the Flash of single-chip microcomputer STM32L151C8, no Can revise, methane concentration can be calculated when thermal balance according to following formula (1):

${\mathrm{\α}}_{CH4}=312.5(\frac{P-P_0}{k(T_d-T_0)}-1)---\left(1\right)$

In formula, α_CH4For methane concentration, P is the electrical power that detecting element consumes, following formula (2) calculate, T_dFor measuring cell temperature, T₀For ambient temperature, measure DS18B20, P₀With k it is and Intelligent methane The parameter that all range sensor structure is relevant, by test determination, is saved in single-chip microcomputer STM32L151C8 EEPROM in；

$P=\frac{{V_1}^2}{RTb+RTw}---\left(2\right)$

When being in catalysis burning duty, single-chip microcomputer STM32L151C8 is exported by DAC and changes The HeatVoltage voltage of the in-phase input end of input amplifier, to black element and white power elements, enters it Row is heated and maintained at 400 DEG C, then methane occurs catalyst combustion reaction on black element, releases heat and makes black unit The temperature of part raises, the resistance of the most black element by higher than the resistance of white element, the resistance of black element and white element Difference is proportional with methane concentration, obtains black element and the numerical value of white element accordingly by following formula (3), by following formula (4) resistance is obtained poor；

$\left\{\begin{array}{c}\begin{array}{cc}{V}_0=2V_2,& V_1=2V_3\end{array}\\ \frac{V_0}{R311+RTb+RTw}(RTb+RTw)=V_1\\ \frac{V_0}{R311+RTb+RTw}RTw=V_4\end{array}\right.---\left(3\right)$

Δ RT=RTb-RTw (4)

In formula, R311 is the 3rd resistance, and RTb is black element；RTw is white element；Δ RT is black element RTb Difference with white element RTw；V₀For by the 3rd resistance R311, the 4th resistance R312, RTb+RTw and the 5th The running voltage of resistance R313 composition electric bridge；V₂It it is the output voltage of the 5th resistance R313；V₁For RTb+RTw Output voltage, be that RTb, RTw, the 6th resistance R314 and the 7th resistance R315 form electric bridge simultaneously Running voltage；V₃It is the output voltage of the 7th resistance R315, V₄Output voltage for white element RTw；

In EEPROM in single chip microcomputer, preserve the relation table of black-and-white component resistance difference and methane concentration, By the concentration that i.e. can get methane of tabling look-up.

A kind of full scale methane concentration measuring method the most according to claim 6, it is characterised in that: adopt Use I²C interrupts receiving data, interrupts the data after receiving and processes in communication module, and router is also at mould Block completes；I²The application layer data bag of C agreement is by address, function number, variable name, variate-value and check code Composition；When Intelligent methane all range sensor does not the most carry out address initialization or needs to reset address Time, can be in communication with by broadcast address, including carrying out address distribution, Intelligent methane gamut senses Device is saved in the EEPROM of its single-chip microcomputer STM32L151C8, the address of distribution without again after power down Secondary initialization；After the distribution of address, the Intelligent methane all range sensor with different address can connect into I²C Web vector graphic, transmitter can connect multiple has I²The dissimilar Intelligent methane gamut sensing of C interface Device.