CN102879124A - Temperature acquisition module - Google Patents
Temperature acquisition module Download PDFInfo
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- CN102879124A CN102879124A CN2012103811362A CN201210381136A CN102879124A CN 102879124 A CN102879124 A CN 102879124A CN 2012103811362 A CN2012103811362 A CN 2012103811362A CN 201210381136 A CN201210381136 A CN 201210381136A CN 102879124 A CN102879124 A CN 102879124A
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Abstract
The invention discloses a temperature acquisition module. The temperature acquisition module, an external upper computer, an external direct-current power source and at least one PT100 probe are electrically connected with one another, and the temperature acquisition module comprises a microcontroller, a PT100 acquisition channel selecting address wire, a single-channel differential ADC (analog-to-digital converter), two precision constant-current sources, an analog multiplexer, a two-path precision voltage signal amplification circuit and at least one two/three-wire selector switch. The temperature acquisition module has the advantages that temperature data can be effectively and accurately acquired by the aid of a combination of circuits and elements such as the single-channel differential ADC, the precision constant-current sources and the double-path precision voltage signal amplification circuit and a constant-current and differential sampling principle, free switching between a two-wire temperature data acquisition mode and a three-wire temperature data acquisition mode can be realized owing to the two/three-wire selector switches of the temperature acquisition module, and accordingly the temperature acquisition module is adaptive to the two temperature data acquisition modes.
Description
Technical field
The present invention relates to a kind of temperature collect module, relate in particular to a kind of can between two-wire system temperature acquisition pattern, three-wire system temperature acquisition pattern, the switching arbitrarily, and the temperature collect module that adopts constant current, difference sampling pattern to sample.
Background technology
In the wind-powered electricity generation industry, need to gather the Primary Components such as motor, bearing, oil temperature, automatically controlled device, indoor environment, extravehicular environment or environment temperature, require simultaneously the temperature acquisition device to possess higher antijamming capability, and PT100 have temperature-measuring range wide, be easy to encapsulation, good stability, precision than high, temperature collect module is widely used in the temp measuring system of wind-powered electricity generation industry.
Yet, in the PT100 of routine temperature collect module, usually adopt the method for constant voltage bridge-drive PT100 to realize temperature survey, in the method, the constant voltage type of drive is because electric current is less, and line impedance is large, therefore poor anti jamming capability, and require very high to power quality; Realize multi pass acquisition in order to satisfy single acquisition module simultaneously, need several constant voltage electric bridges, ADC passage, so that cost increases exponentially, structure is also more complicated, has also further reduced the interference free performance of using in industrial environment like this; Simultaneously the conformity error between the different ADC passages needs production firm's calibration, has further increased the time cost of production, detection.
And, when temperature collect module collecting temperature data, can't eliminate the impact that is connected to the cable resistance between PT100 probe and the temperature collect module, be the large problem that temperature collect module need to solve so how to guarantee the accuracy of image data.
Summary of the invention
The objective of the invention is the defective for the existence of above-mentioned background technology, a kind of temperature collect module that utilizes constant current, difference sampling principle to carry out temperature sampling is provided.
For achieving the above object, a kind of temperature collect module of the present invention is electrically connected mutually with outside host computer, external dc power and at least one PT100 probe, and described temperature collect module comprises a microcontroller, PT100 sampling channel selection address wire, a single channel difference ADC, two precision constant current sources, a multi-channel analog multiplexer, a two-way accurate voltage signal amplification circuit and at least one or two/three-wire system selector switch; Described multi-channel analog multiplexer further comprises at least one multi-channel analog multiplexer switches group; Described microcontroller (one) is used for receiving the control command of host computer, and to host computer transmission sample temperature Value Data, (2) be used for the shutoff of control two/three-wire system selector switch with the adaptive two-wire system temperature acquisition pattern of difference and three-wire system temperature acquisition pattern, (3) be used for calculating corresponding sample temperature value and storage constantly according to the encoded radio that single channel difference ADC sends into, (4) be used for control two precision constant current sources and produce respectively a steady current and control two steady currents and pour into synchronously in the same PT100 probe, (five) are used for the calculated address signal and control same group of shutoff that is connected in the multi-channel analog multiplexer switches of same PT100 probe pouring in the same PT100 probe selectively two precision constant current sources are produced respectively steady current; Described PT100 sampling channel selects address wire as the address signal transmission channel of microcontroller; Described precision constant current source is to described PT100 probe supply steady current; Close when described multi-channel analog multiplexer () is used for generating the switching value signal and controlling selectively same group of built-in multi-channel analog multiplexer switches that is connected in same PT100 probe by the switching value signal according to address signal and disconnect, (2) be used for to receive the address signal that microcontroller sends and be translated into current output signal, realize the electric current that two precision constant current sources are exported is poured in the PT100 probe synchronously; Described two-way accurate voltage signal amplification circuit is used for gathering respectively the terminal voltage of two precision constant current source output terminals, and the terminal voltage of amplifying synchronously two precision constant current source output terminals; The voltage that described single channel difference ADC is used for two-way accurate voltage signal amplification circuit is sent into carries out the difference computing, and the sampled voltage that obtains by the difference computing is encoded accordingly.
In sum, a kind of temperature collect module of the present invention is because merging nationality can be realized temperature data effectively by the sampling principle of constant current, difference accurate collection by circuit elements set of devices such as single channel difference ADC, precision constant current source and two-way accurate voltage signal amplification circuits, and two/three-wire system selector switch of temperature collect module of the present invention can realize freely switching of two-wire system temperature data acquisition pattern and three-wire system temperature data acquisition pattern, so can adaptive two kinds of temperature data acquisition patterns.
Figure of description
Fig. 1 is the high-level schematic functional block diagram of a kind of temperature acquisition mould of the present invention.
Fig. 2 is the equivalent circuit diagram of popping one's head in the interconnective PT100 of temperature collect module of the present invention.
Embodiment
By describing technology contents of the present invention, structural attitude in detail, reached purpose and effect, below hereby exemplify embodiment and cooperate accompanying drawing to give in detail explanation.
See also Fig. 1, a kind of temperature collect module 100 of the present invention is electrically connected mutually with outside host computer 200, external dc power 400 and at least one PT100 probe (platinum resistance thermometer sensor, probe) 300.Described each PT100 probe 300 is all realized being electrically connected and the signal transmission with this temperature collect module 100 by three cables, and the resistance value of described cable is
A kind of temperature collect module 100 of the present invention comprises a microcontroller (MCU) 1, PT100 sampling channel selection address wire 2, a single channel difference ADC3, two precision constant current sources 4, a multi-channel analog multiplexer 5, a two-way accurate voltage signal amplification circuit 6, at least one or two/three-wire system selector switch 7, a digital-to-analog power supply 8 and a RS485 transceiver 9.
Particularly, temperature collect module 100 of the present invention passes through described RS485 receiver and realizes being electrically connected and the signal transmission such as outside host computers 200 such as wind turbine control systems, particularly, described RS485 transceiver 9 is used for the RS485 control signal of transmitting-receiving host computer 200 and transmits to realize that to microcontroller 1 microcontroller 1 transmits the sample temperature Value Data to host computer 200; By described digital-to-analog power supply 8 electric energy of external dc power 400 is supplied with to temperature collect module 100 of the present invention; At least articulate PT100 probe 300 by described multi-channel analog multiplexer 5.
Described multi-channel analog multiplexer 5 is the multi-channel analog multiplexer of two-way synchronized model.Described multi-channel analog multiplexer 5 further comprises a code translator 51, at least one multi-channel analog multiplexer switches group 52.
Described multi-channel analog multiplexer switches group 52 further comprises the first multi-channel analog multiplexer switches group 521, the second multi-channel analog multiplexer switches group 522.The number of switches of first, second multi-channel analog multiplexer switches group 521 is equal, and corresponding one by one.Described the first multi-channel analog multiplexer switches group 521 further comprise some switches 5211 ..., 521N, wherein N
8, and N is natural number.The second multi-channel analog multiplexer switches group 522 further comprise some switches 5221 ..., 522N, wherein N
8, and N is natural number.The common multi-channel analog multiplexer switches group 52 that consists of wherein of a pair of inductive switch among a switch in described the first multi-channel analog multiplexer switches group 521 and the second multi-channel analog multiplexer switches group 522N.For example, the switch 5211 in the first multi-channel analog multiplexer switches group 521 and the 5221 common multi-channel analog multiplexer switches groups 52 that consist of wherein of the switch in the second multi-channel analog multiplexer switches group 522; Switch 5222 common another multi-channel analog multiplexer switches group 52...... that consist of wherein in switch 5212 in the first multi-channel analog multiplexer switches group 521 and the second multi-channel analog multiplexer switches group 522
Described precision constant current source is the 2mA precision constant current source.For ease of difference, special with described two precision constant current sources difference called after: precision constant current source-A41 and precision constant current source-B42.
Described microcontroller 1(one) for the control command that receives host computer 200, and to host computer 200 transmission sample temperature Value Datas, (2) be used for the shutoff of control two/three-wire system selector switch 7 with the adaptive two-wire system temperature acquisition pattern of difference and three-wire system temperature acquisition pattern, (3) be used for receiving encoded radio and the sample temperature value that calculates the corresponding moment and the storage that single channel difference ADC3 sends into, (4) be used for control two precision constant current sources 4 and produce respectively a steady current and control two steady currents and pour into synchronously in the same PT100 probe 300, (five) are used for the calculated address signal and control a shutoff that is connected in the multi-channel analog multiplexer switches group 52 of same PT100 probe 300 pouring in the same PT100 probe 300 selectively two precision constant current sources 4 are produced respectively steady current.
Described microcontroller 1 further comprises an EEPROM11 (EEPROM (Electrically Erasable Programmable Read Only Memo)), a UART12(Universal Asynchronous Receiver ﹠ dispensing device), an I/O interface 13(signal input/output interface), a SPI interface 14 and a SRAM15(static RAM).
Described UART12 realizes being electrically connected and the signal transmission with upper level host computer 200 by described RS485 transceiver 9 and RS485 bus.
Described PT100 sampling channel selects address wire 2 as the transmission channel of the address signal of microcontroller 1, and this described PT100 sampling channel selects address wire 2 to be connected between microcontroller 1 and the multi-channel analog multiplexer 5.
In this preferred embodiment, described single channel difference ADC3 is one 16 single channel difference ADC.Described single channel difference ADC3 is by SPI interface 14 realizations of described microcontroller 1 and being electrically connected and the signal transmission of microcontroller 1.
In addition, described microcontroller 1 selects address wire 2 to realize being electrically connected and the signal transmission with the code translator 51 of multi-channel analog multiplexer 5 by I/O interface 13, PT100 sampling channel.
Close when described this multi-channel analog multiplexer 5(one) being used for generating the switching value signal and controlling selectively same group of built-in multi-channel analog multiplexer switches that is connected in same PT100 probe 300 52 by the switching value signal according to address signal and disconnect; (2) be used for receiver address signal and be translated into current output signal, can realize the steady current that precision constant current source-A41 and precision constant current source-B42 export is poured in the PT100 probe 300 synchronously.
Described code translator 51 is used for receiving the address signal that microcontroller 1 sends and is translated into described switching value signal and current output signal.
In this preferred embodiment, described code translator 51 can adopt 38 line code translators, also can adopt 4 16 line code translators.In the specific embodiment, when described code translator 51 adopted 38 line code translators, multi-channel analog multiplexer 5 can be mounted with 8 PT100 probes 300 at the most; When described code translator 51 adopted 4 16 line code translators, multi-channel analog multiplexer 5 can articulate 16 PT100 probes 300 at the most.
Slower because being changed by collecting temperature, so that the sampling period of temperature data is also insensitive, therefore temperature sampling module 100 of the present invention is for these reasons, used multi-channel analog multiplexer 5.This multi-channel analog multiplexer 5 can guarantee that the precision of collecting temperature is enough high in the situation that only have a single channel difference ADC3, two precision constant current sources 4 and a two-way accurate voltage signal amplification circuit 6; On the basis of error in tolerance interval, with
The pop one's head in quantity of 300 cut-in temperature acquisition modules 100 of Expansion PT100.
The output terminal of described wherein one precision constant current source-A41 connects a wherein input end of two-way accurate voltage signal amplification circuit 6, simultaneously, the first multi-channel analog multiplexer switches group 521 each switch are connected to the output terminal of above-mentioned precision constant current source-A41 in the mode in parallel with two-way accurate voltage signal amplification circuit 6; The output terminal of another precision constant current source-B42 connects another input end of two-way accurate voltage signal amplification circuit 6, simultaneously, the second multi-channel analog multi-channel analog multiplexer switches group 522 each switch are connected to the output terminal of precision constant current source-B42 in the mode in parallel with two-way accurate voltage signal amplification circuit 6.
Described precision constant current source 4 is used for to PT100 probe 300 supply steady currents.Particularly, described precision constant current source-A41 and precision constant current source-B42 be used for to receive current output signal that multi-channel analog multiplexer 5 sends and export respectively corresponding electric current by the control of current output signal
, electric current
Give the same PT100 probe 300 that is articulated on the temperature collect module 100 of the present invention.In this specific embodiment, precision constant current source-A41 and precision constant current source-B42 output current is equal and constant, namely
Because temperature collect module 100 of the present invention and each PT100 probe 300 are all realized interconnecting by one group of cable, every group of three cables, when actual temperature gathers, because of the resistance sizes of every cable on the sampling precision impact of the sample temperature Value Data of temperature collect module 100 of the present invention greatly, therefore need to adopt the identical cable of length resistance of same model.
Particularly, see also Fig. 2, an opposite end X of described PT100 probe 300 is electrically connected with precision constant current source A41 realization wherein by the switch in described the first multi-channel analog multiplexer switches group 521 and a cable; Another opposite end Y of described PT100 probe 300 is electrically connected with another precision constant current source B42 realization wherein by a pair of inductive switch in described the second multi-channel analog multiplexer switches group 522 and a cable; Simultaneously, after described cable, 7 series connection of one or two/three-wire system selector switch, another opposite end Y of the free end of cable and described PT100 probe 300 interconnects, free time of two/three-wire system selector switch 7 end be connected in the second multi-channel analog multiplexer switches group 52 on the inductive switch, namely wherein a cable with after two/three-wire system selector switch 7 is connected first, in parallel with a cable again, the circuit of above-mentioned formation is connected between another opposite end Y of the switch of the second multi-channel analog multiplexer switches group 522 and PT100 probe 300, and at resistance
Pass through a wire ground connection with two/three-wire system selector switch 7.
Setting the pop one's head in resistance of resistance of 300 particular moments of PT100 is
The resistance of the single switch resistance of multi-channel analog multiplexer switches group is
The terminal voltage of precision constant current source-A41, precision constant current source-B42 output terminal is respectively
,
Particularly, two-way accurate voltage signal amplification circuit 6 is used for gathering respectively the terminal voltage of two precision constant current sources, 4 output terminals, and the terminal voltage of two precision constant current sources, 4 output terminals is with respect to the voltage difference between the terminal voltage of earth terminal.Described two-way accurate voltage signal amplification circuit 6 differences according to two/three-wire system temperature acquisition pattern,
, the steady current that produces of two precision constant current sources 4
, single cable resistance value
, the PT100 300 specified temps resistance constantly of popping one's head in
And the single switch resistance of multi-channel analog multiplexer switches group 52
Respectively with the terminal voltage of two precision constant current sources, 4 output terminals
,
Show, and amplify synchronously respectively the terminal voltage of precision constant current source A41 and precision constant current source B42 output terminal
,
Doubly to obtain respectively
,
And can guarantee output voltage
,
In the sampled voltage scope of single channel difference ADC3.
When temperature collect module 100 of the present invention switched to two-wire system temperature acquisition pattern, the terminal voltage of two precision constant current sources, 4 output terminals was respectively and can be expressed as:
And
When temperature collect module 100 of the present invention switched to three-wire system temperature acquisition pattern, the terminal voltage of two precision constant current sources, 4 output terminals can be expressed as respectively:
And
Enlargement factor
Can also can be less than 1 greater than 1.In this specific embodiment,
Greater than 1.
In a preferred embodiment, the input impedance of the two-way accurate voltage signal amplification circuit 6 of temperature collect module 100 of the present invention at least greater than
Ω is because described two-way accurate voltage signal amplification circuit 6 is realized mutual electric connection in parallel with multi-channel analog multiplexer 5, therefore enter the electric current of two-way accurate voltage signal amplification circuit 6
,
Minimum; And the input impedance of two-way accurate voltage signal amplification circuit 6 is enough large, therefore enter into the electric current of two-way accurate voltage signal amplification circuit 6
,
Can ignore.
The voltage that described single channel difference ADC3 is used for two-way accurate voltage signal amplification circuit is sent into carries out the difference computing, and the sampled voltage that obtains by the difference computing is encoded accordingly.Particularly, described single channel difference ADC3 is for the voltage that two-way accurate voltage signal amplification circuit 6 is sent into
, voltage
Carry out the difference computing and obtain sampled voltage
, and described single channel difference ADC3 is to voltage
And
Carry out following calculating:
(when two-wire system gathers mould,
For:
During the three-wire system drainage pattern,
For:
), and by built-in output encoder rule to sampled voltage
Encode accordingly, and then draw corresponding encoded radio
The built-in coding rule of described single channel difference ADC3 is
(wherein,
Be known number).
Described two/three-wire system selector switch 7 is used for closing selectively and disconnecting with freely switching between two-wire system temperature acquisition pattern, three-wire system temperature acquisition pattern respectively according to the drainage pattern of temperature collect module 2.
Temperature collect module 100 described sample temperature Value Datas of the present invention are principles of utilizing constant current, difference sampling, and draw corresponding sample temperature data by precision constant current source-A41, precision constant current source-B42, two-way accurate voltage signal amplification circuit 6, single channel difference ADC3, microcontroller 1 and built-in corresponding algorithm.Described each sample temperature Value Data is stored among the SRAM15 of microcontroller 1.
Described digital-to-analog power supply 8 is used for by external power source 400 to microcontroller 1, RS485 transceiver 9, single channel difference ADC3, two-way accurate voltage signal amplification circuit 6 and multi-channel analog multiplexer 5 supply electric energy.
The course of work of a kind of temperature collect module 100 of the present invention is as follows:
When a kind of temperature collect module 100 of the present invention switches to three-wire system temperature acquisition pattern, two/three-wire system selector switch 7 is in off-state, and described microcontroller 1 selects address wire 2 address signal to be sent to the code translator 51 of multi-channel analog multiplexer 5 by the PT100 sampling channel; Described code translator 51 is translated into address signal respectively corresponding switching value signal and current output signal and sends, and the same multi-channel analog multiplexer switches of described switching value signal controlling group 52 is turn-offed simultaneously; Simultaneously, the current output signal control precision constant current source-A41 that is translated by address signal, the corresponding output current of precision constant current source-B42
, electric current
And pour into synchronously same PT100 probe 300; Described two-way accurate voltage signal amplification circuit 6 gathers respectively the terminal voltage of precision constant current source-A41, precision constant current source-B42 output terminal
,
And according to the circuit relationships of three-wire system temperature acquisition pattern,
, the steady current that produces of two precision constant current sources 4
, single cable resistance value
, the PT100 300 specified temps resistance constantly of popping one's head in
And the single switch resistance of multi-channel analog multiplexer switches group 52
Respectively with the terminal voltage of precision constant current source-A41, precision constant current source-B42
,
Show, namely have following relation:
The terminal voltage of 6 couples of precision constant current source-A41 of described two-way accurate voltage signal amplification circuit
And the terminal voltage of precision constant current source-B42
Amplify
Doubly, namely
,
, described
,
Be sent in the single channel difference ADC3 by two-way accurate voltage signal amplification circuit 6; Single channel difference ADC3 is to sending
,
Carry out the difference computing, and then obtain sampled voltage
, described single channel difference ADC3 is in conjunction with built-in output encoder rule
(wherein,
Be known number) sampled voltage is carried out
Coding is also exported corresponding encoded radio
, described encoded radio
Further send microcontroller 1 to and calculate corresponding temperature resistance constantly by microcontroller 1 by single channel difference ADC3
Resistance
After microcontroller 1 reception, microcontroller 1 divides kilsyth basalt and calculates corresponding sample temperature Value Data and storage by the piece-wise linearization algorithm by inquiry microcontroller 1 built-in PT100; Described microcontroller 1 transmits the sample temperature Value Data according to the data demand of outside host computer 200 to outside host computer 200.
When a kind of temperature collect module 100 of the present invention switches to the two-wire system drainage pattern, two/three-wire system selector switch 7 is in closed condition, and described microcontroller 1 selects address wire 2 address signal to be sent to the code translator 51 of multi-channel analog multiplexer 5 by the PT100 sampling channel; Described this code translator 51 is translated respectively switching value signal and current output signal with address signal and is sent, and same group of multi-channel analog multiplexer switches of described switching value signal controlling group 52 is closed simultaneously; Simultaneously, the current output signal control precision constant current source-A41 that is translated by address signal, the electric current of the corresponding output of precision constant current source-B42
, electric current
And pour into synchronously same PT100 probe 300; Described two-way accurate voltage signal amplification circuit 6 gathers respectively the terminal voltage of precision constant current source-A41, precision constant current source-B42 output terminal
,
And according to the circuit relationships of two-wire system drainage pattern,
, the steady current that produces of two precision constant current sources 4
, single cable resistance value
, the PT100 300 specified temps resistance constantly of popping one's head in
And the single switch resistance of multi-channel analog multiplexer switches group 52
Respectively with the terminal voltage of precision constant current source-A41, precision constant current source-B42
,
Show, namely have following relation:
The terminal voltage of 6 pairs of precision constant current sources of described two-way accurate voltage signal amplification circuit-A41 output terminal
And the terminal voltage of precision constant current source-B42 output terminal
Amplify
Doubly, namely
,
, described
,
Be sent in the single channel difference ADC3 by two-way accurate voltage signal amplification circuit 6; Single channel difference ADC3 is to sending
,
Carry out the difference computing, and then obtain sampled voltage
, described single channel difference ADC3 is in conjunction with built-in output encoder rule
(wherein,
Be known number) sampled voltage is carried out
Coding is also exported corresponding encoded radio
, described encoded radio
Further send microcontroller 1 to and calculate right resistance by microcontroller 1 by single channel difference ADC3
(should
Be defaulted as is that PT100 probe 300 is at relevant temperature resistance constantly), the PT100 during microcontroller 1 is further built-in by inquiry microcontroller 1 divides kilsyth basalt and calculates corresponding sample temperature Value Data and storage by the piece-wise linearization algorithm; Described microcontroller 1 transmits the sample temperature Value Data according to the data demand of outside host computer 200 to outside host computer 200.
Need to prove because of in the two-wire system temperature acquisition pattern, the corresponding temperature that calculates resistance value constantly is essentially
, and this resistance
In
Can't be eliminated, therefore there is error in the temperature value that calculates therefrom, but because of the resistance value of single cable
Be far smaller than
, so that the temperature value that calculates therefrom remains in the relatively accurate scope.
In sum, a kind of temperature collect module 100 of the present invention is because merging nationality can be realized temperature data effectively by the sampling principle of constant current, difference accurate collection by circuit elements set of devices such as single channel difference ADC3, precision constant current source 4 and two-way accurate voltage signal amplification circuits 6, and two/three-wire system selector switch 7 of temperature collect module 100 of the present invention can realize freely switching of two-wire system temperature data acquisition pattern and three-wire system temperature data acquisition pattern, so can adaptive two kinds of temperature data acquisition patterns.
Above-described technical scheme only is the preferred embodiment of a kind of temperature collect module 100 of the present invention, within any equivalent transformation or the scope of the replacement claim that is included in this patent doing on a kind of temperature collect module of the present invention 100 bases.
Claims (18)
1. a temperature collect module is electrically connected mutually with outside host computer, external dc power and at least one PT100 probe, it is characterized in that:
This temperature collect module comprises a microcontroller, PT100 sampling channel selection address wire, a single channel difference ADC, two precision constant current sources, a multi-channel analog multiplexer, a two-way accurate voltage signal amplification circuit and at least one or two/three-wire system selector switch;
Described multi-channel analog multiplexer further comprises at least one multi-channel analog multiplexer switches group;
Described microcontroller (one) is used for receiving the control command of host computer, and to host computer transmission sample temperature Value Data, (2) be used for the shutoff of control two/three-wire system selector switch with the adaptive two-wire system temperature acquisition pattern of difference and three-wire system temperature acquisition pattern, (3) be used for calculating corresponding sample temperature value and storage constantly according to the encoded radio that single channel difference ADC sends into, (4) be used for control two precision constant current sources and produce respectively a steady current and control two steady currents and pour into synchronously in the same PT100 probe, (five) are used for the calculated address signal and control same group of shutoff that is connected in the multi-channel analog multiplexer switches of same PT100 probe pouring in the same PT100 probe selectively two precision constant current sources are produced respectively steady current;
Described PT100 sampling channel selects address wire as the address signal transmission channel of microcontroller;
Described precision constant current source is to described PT100 probe supply steady current;
Close when described multi-channel analog multiplexer () is used for generating the switching value signal and controlling selectively same group of built-in multi-channel analog multiplexer switches that is connected in same PT100 probe by the switching value signal according to address signal and disconnect, (2) be used for to receive the address signal that microcontroller sends and be translated into current output signal, realize the electric current that two precision constant current sources are exported is poured in the PT100 probe synchronously;
Described two-way accurate voltage signal amplification circuit is used for gathering respectively the terminal voltage of two precision constant current source output terminals, and the terminal voltage of amplifying synchronously two precision constant current source output terminals;
The voltage that described single channel difference ADC is used for two-way accurate voltage signal amplification circuit is sent into carries out the difference computing, and the sampled voltage that obtains by the difference computing is encoded accordingly.
2. a kind of temperature collect module according to claim 1, it is characterized in that: described single channel difference ADC is one 16 single channel difference ADC.
3. a kind of temperature collect module according to claim 1, it is characterized in that: described multi-channel analog multiplexer is two-way synchronized model multi-channel analog multiplexer.
4. a kind of temperature collect module according to claim 1, it is characterized in that: described precision constant current source is the 2mA precision constant current source.
5. a kind of temperature collect module according to claim 1 is characterized in that: described PT100 sampling channel selects address wire to be connected between microcontroller and the multi-channel analog multiplexer.
6. a kind of temperature collect module according to claim 1, it is characterized in that: described multi-channel analog multiplexer further comprises a code translator, this code translator is used for receiving the address signal that microcontroller sends and is translated into switching value signal and current output signal.
7. a kind of temperature collect module according to claim 6, it is characterized in that: described code translator can adopt 38 line code translators, and when described code translator can adopt 38 line code translators, multi-channel analog multiplexer device can be mounted with 8 PT100 probes at the most.
8. a kind of temperature collect module according to claim 6, it is characterized in that: described code translator can adopt 4 16 line code translators, and when described code translator adopted 4 16 line code translators, the multi-channel analog multiplexer can articulate 16 PT100 probes at the most.
9. a kind of temperature collect module according to claim 1, it is characterized in that: described temperature collect module further comprises a RS485 transceiver, and described RS485 transceiver is used for the RS485 control signal of transmitting-receiving host computer and transmits to realize that to microcontroller microcontroller transmits the sample temperature Value Data to host computer.
10. a kind of temperature collect module according to claim 1, it is characterized in that: described temperature collect module further comprises a digital-to-analog power supply, and this digital-to-analog power supply is used for external external power source to realize microcontroller, two-way accurate voltage signal amplification circuit, single channel difference ADC, multi-channel analog multiplexer and the RS485 transceiver supply electric energy to temperature collect module.
11. a kind of temperature collect module according to claim 1 is characterized in that: described microcontroller further comprises an EEPROM, a URAT, an I/O interface, a SPI interface and a SRAM.
12. reach according to claim 11 13 described a kind of temperature collect modules, it is characterized in that: described UART realizes being electrically connected and the signal transmission with the upper level host computer by described RS485 transceiver and RS485 bus, described microcontroller selects address wire and the code translator of multi-channel analog multiplexer to realize being electrically connected and the transmission of coded signal by I/O interface, PT100 sampling channel, described single channel difference ADC by described microcontroller the SPI Interface realization and microcontroller be electrically connected and signal transmits.
13. a kind of temperature collect module according to claim 11 is characterized in that: described sample temperature Value Data is stored among the SRAM of microcontroller.
14. a kind of temperature collect module according to claim 1 is characterized in that: described multi-channel analog multiplexer switches group further comprises the first multi-channel analog multiplexer switches group, the second multi-channel analog multiplexer switches group.
15. a kind of temperature collect module according to claim 14, it is characterized in that: the number of switches of first, second multi-channel analog multiplexer switches group equates, and corresponding one by one, the common multi-channel analog multiplexer switches group that consists of wherein of the switch in described the first multi-channel analog multiplexer switches group and a pair of inductive switch in the second multi-channel analog multiplexer switches group.
16. a kind of temperature collect module according to claim 14, it is characterized in that: the output terminal of a described wherein precision constant current source connects a wherein input end of two-way accurate voltage signal amplification circuit, simultaneously, first each switch of multi-channel analog multiplexer switches group is connected to the above-mentioned wherein output terminal of a precision constant current source in the mode in parallel with two-way accurate voltage signal amplification circuit.
17. a kind of temperature collect module according to claim 14, it is characterized in that: the output terminal of another precision constant current source connects another input end of two-way accurate voltage signal amplification circuit, simultaneously, second each switch of multi-channel analog multi-channel analog multiplexer switches group is connected to the output terminal of above-mentioned another precision constant current source in the mode in parallel with two-way accurate voltage signal amplification circuit.
18. a kind of temperature collect module according to claim 1 is characterized in that: the input impedance of described two-way accurate voltage signal amplification circuit at least should greater than
Ω.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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| CN106444905A (en) * | 2016-09-19 | 2017-02-22 | 中国科学院合肥物质科学研究院 | High-temperature superconducting welding temperature synchronous measurement controller |
| CN107655586A (en) * | 2017-10-11 | 2018-02-02 | 珠海格力电器股份有限公司 | Temperature measuring circuit and detection method thereof |
| CN107655586B (en) * | 2017-10-11 | 2024-03-29 | 珠海格力电器股份有限公司 | Temperature measuring circuit and detection method thereof |
| CN107990994A (en) * | 2017-11-09 | 2018-05-04 | 中国科学院长春光学精密机械与物理研究所 | A kind of multichannel Pt Resistance Temperature Measuring Circuit and method |
| CN107941363A (en) * | 2017-12-28 | 2018-04-20 | 重庆工商大学 | Temperature pick-up device and method based on program-controlled double constant-current supplies |
| CN107941363B (en) * | 2017-12-28 | 2019-11-26 | 重庆工商大学 | Temperature pick-up device and method based on program-controlled double constant-current supplies |
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