CN103903412B - CAN (Controller Area Network) bus to 4-20mA data signal conversion device for NOx sensor - Google Patents
CAN (Controller Area Network) bus to 4-20mA data signal conversion device for NOx sensor Download PDFInfo
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- 238000006243 chemical reaction Methods 0.000 title claims abstract description 20
- 238000012545 processing Methods 0.000 claims abstract description 32
- 238000002955 isolation Methods 0.000 claims abstract description 29
- 238000000034 method Methods 0.000 claims description 16
- 238000013024 troubleshooting Methods 0.000 claims 1
- 230000008054 signal transmission Effects 0.000 abstract description 5
- 230000005540 biological transmission Effects 0.000 abstract description 3
- 230000005693 optoelectronics Effects 0.000 abstract 2
- 239000000872 buffer Substances 0.000 description 3
- 238000004891 communication Methods 0.000 description 3
- 238000013501 data transformation Methods 0.000 description 3
- 238000001514 detection method Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 241001269238 Data Species 0.000 description 1
- 206010033799 Paralysis Diseases 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
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- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000013213 extrapolation Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
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Abstract
The invention belongs to the field of industrial control, and particularly relates to a CAN (Controller Area Network) bus to 4-20mA data signal conversion device for a NOx sensor. The device is suitable for converting digital quantity signals based on a CAN protocol into industrially general 4-20mA signal based on the CAN protocol. The data signal conversion device comprises the NOx sensor 1, a first CAN bus interface 2, a second CAN bus interface 3, a data processing module 5, a first optoelectronic isolation module 4, a second optoelectronic isolation module 6 and a 4-20mA output circuit 7. The signal transmission of the NOx sensor in the device can be in two work patterns; when a redundant data conversion mode is adopted, one path of data transmission is converted into the other path of data transmission when a fault occurs, and the reliability of system operation is ensured.
Description
Technical field
The invention belongs to industrial control field, and in particular to a kind of suitable for will can be assisted based on CAN based on CAN protocol
The CAN for NOx sensor of the 4-20mA signals that the digital quantity signal dress of view is changed to industrial general turns the number of 4-20mA
According to chromacoder.
Background technology
With the development and the raising of environmental consciousness of society, the world is required the discharge capacity of NOx in internal combustion engine tail gas discharge
It is more and more stricter.In order to rapid accurately detection NOx content, the emission problem of NOx is solved, the application of NOx sensor becomes
It is more and more universal.At present major part NOx sensor inside is CAN control unit, and by CAN NOx concentration is exported
Size.CAN has higher bit rate, higher electromagnetism interference and very strong error-detection error-correction ability, and has
Low cost, reliability is high, install maintenance cost it is low the characteristics of, automobile, shipping industry, communications and transportation, work have been widely used in
The fields such as industry control.
But in Industry Control Application field, particularly PLC control system, CAN application is not extensive, even if having
CAN module, its price is also high.In industrial control system, 4-20mA analog signalses are widely used, and it uses 4mA
Zero-signal is represented, with 20mA the full scale of signal is represented, and being less than signals of the 4mA higher than 20mA is used for the warning of various failures.
4-20mA analog signalses have output distance remote, signal strong antijamming capability, advantage easy to use.
In order to NOx sensor is applied to into industrial control field, NOx sensor CAN data and 4- must be just realized
Conversion between 20mA analog signalses, therefore also it is accomplished by DTU.Chinese Patent Application No.
201020661289.9 propose a kind of analogue quantity output device, including power supply, microprocessor, CAN unit, Phototube Coupling
Circuit and DA change-over circuits, receive digital quantity signal and are converted to analog signalses, realize the process to signal.Chinese patent application
Numbers 201120349179.3 propose a kind of photoelectric isolation type 4-20 mA output device, including microprocessor, switch optocoupler, whole
Shape device, D/A converter and 4~20mA circulation generators, free from error conversion digital signal is 4~20mA analog signalses.Due to
Requirement of the industrial circle to reliability is higher, and above-mentioned patent is single channel conversion equipment, and reliability is not high, environmental suitability compared with
Difference, application is restricted.
A kind of two-way 4-20mA DC analogue quantity output devices, the dress are proposed in China Patent No. 200710132579.7
Put and be made up of high speed optoisolator, D/A converter, operational amplifier, voltage-reference;Wherein, high speed optoisolator, number/
Weighted-voltage D/A converter, the connection of operational amplifier sequential series, the circuit can simulate two-way SPI communication line by the I/O port of FPGA, will
The parallel digital information that microprocessor is given changes into the serial digital stream output of DAC requirements, realizes the DC analogue quantity of 4-20mA
Output.The conversion equipment defect is, when breaking down all the way, to cause corresponding opposite side to paralyse, and severe one can cause
Whole device cannot normal work.NOx sensor signal transmission in apparatus of the present invention can adopt two kinds of mode of operations, work as employing
During redundant data translative mode, another road is can switch to after all the way data transfer breaks down, it is ensured that system operation can
By property.
The content of the invention
It is an object of the invention to provide a kind of CAN for NOx sensor turns the data-signal conversion of 4-20mA
Device.
The object of the present invention is achieved like this:
The present invention include NOx sensor 1, the first CAN interface 2, the second CAN interface 3, data processing module 5,
First photoelectric isolation module 4, the second photoelectric isolation module 6,4-20mA output circuits 7, the output digital quantity signal of NOx sensor 1,
Through the signal isolation that two-way CAN passes through photoelectric isolation module 4, data processing module 5 is sent to, data processing module
Signal is sent to 4-20mA output circuits 7 and is converted into 4-20mA analog signalses through the second photoelectric isolation module 6.
Photoelectric isolation module adopts high speed optocoupler TLP521-4, data processing module to adopt the microprocessor of 16 bit
MC9S12XDP512,
The beneficial effects of the present invention is:
NOx sensor signal transmission in apparatus of the present invention can adopt two kinds of mode of operations, when being changed using redundant data
During pattern, another road is can switch to after all the way data transfer breaks down, it is ensured that the reliability of system operation.
Description of the drawings
Fig. 1 is the structural representation of the present invention.
Fig. 2 is the operating diagram of the present invention.
Fig. 3 is the redundant data fault treating procedure of the present invention.
Fig. 4 is the light-coupled isolation output circuit of the present invention.
Fig. 5 is the CAN transceiver circuit of the present invention.
Fig. 6 is the 4-20mA change-over circuits of the present invention.
Specific embodiment
The present invention is described further below in conjunction with the accompanying drawings.
The invention reside in the data-signal conversion equipment that a kind of CAN for NOx sensor turns 4-20mA is provided, tool
Body embodiment is as follows:
CAN for NOx sensor turns the data-signal conversion equipment of 4-20mA, including NOx sensor 1, and CAN is total
Line interface 2,3, data processing module 5, photoelectric isolation module 4,6,4-20mA output circuits 7, working method arrange 8 and LED
Indicate fault alarm 9 etc..Signal transmission between above-mentioned module, is started with NOx sensor 1, sequentially passes through CAN interface 2,3,
Photoelectric isolation module 4, data processing module 5, photoelectric isolation module 6,4-20mA output circuits 7 are converted into digital quantity signal
4-20mA analog signalses.
Wire jumper 8 is arranged by working method, makes this device realize that binary channels is independent and redundant data converts two kinds of work sides
Formula.
NOx sensor 1 exports digital quantity signal, and 4-20mA analog signalses are converted into after data processing, and 4mA is represented
The starting point of NOx sensor range, 20mA represents the terminal of NOx sensor range.
Data processing module 5 can be judged and be processed to the data of NOx sensor 1, adapt to this device in different works
Make to be worked under mode, it is ensured that the reliability of device work.If data processing module 5 judges to break down, LED indicates failure
Warning 9 sends light warning information alert.
Photoelectric isolation module 4,6 pairs of inputs, output datas carry out isolation processing, make this device that there is preferable environment to adapt to
Property, strong antijamming capability.
NOx sensor 1 in Fig. 1, CAN interface 2,3, photoelectric isolation module 4,6, data processing module 5,4-20mA is defeated
Go out circuit 7, working method arranges 8 and LED instruction fault alarm 9.
Present configuration as shown in figure 1, mainly include NOx sensor 1, CAN interface 2,3, data processing module 4,
Photoelectric isolation module 5,6,4-20mA output circuits 7, working method arranges 8 and LED instruction fault alarm 9 etc..Above-mentioned module
Between signal transmission, started with NOx sensor 1, sequentially pass through CAN interface 2,3, photoelectric isolation module 4, data processing mould
The digital quantity signal that NOx sensor 1 is exported is converted to 4-20mA moulds by block 5, photoelectric isolation module 6,4-20mA output circuits 7
Analog quantity signal output.
Present invention work is as shown in Fig. 2 mainly include power circuit, reset circuit, crystal oscillating circuit, microprocessor, optocoupler
Circuit, two-way CAN transmitting-receivings, On-off signal output, analog output composition.Two-way CAN transceiver by photoelectric coupled circuit with it is micro-
Processor exchange data, microprocessor is processed input data, exports 4-20mA analog signalses.On-off signal is exported
Including the working method of microprocessor, harmony visual alarm output etc. is set.
The core of data processing module of the present invention 5 is microprocessor, and microprocessor has more than two-way independent CAN controls
Device, is that the setting of two-way CAN receives interruption, gives corresponding interrupt priority, distributes different reception data buffers, sends out
Data buffer zone is sent, and completes data protocol conversion work.Data processing module 5 receives the data of NOx sensor transmission, deposits
Enter buffer area, according to protocol conversion.
Apparatus of the present invention have function switching signal more than two-way, and by working method 8 wire jumper is arranged, and are capable of achieving double
Independent and redundant data conversion the two kinds of working methods of passage.During independent data transformation mode, each passage can be independent
Work, realizes two-way input and output;During redundant data transformation mode, two passage NOx sensors gather the number of a point
According to through data processing and breakdown judge, data processing module 5 converts a relatively correct data and exports logical to two
Road, realizes the redundancy of passage, it is ensured that the reliability of device.
When the present invention is worked using redundant data transformation mode, data processing module 5 receives two-way CAN simultaneously
Data, to each passage, data processing module 5 first determines whether that data, then will be multiple before this passage whether beyond bound
The mean value and this secondary data of measurement data is compared, and beyond given threshold, judges failure;When two-way CAN data phase
When difference is larger, to each passage, then the extrapolation predicted value of multiple measurement data before this secondary data and this passage is compared,
Take error it is little all the way as right value, failure is thought on another road;When breaking down, LED indicates that fault alarm 9 sends light
Report to the police.
This device receives NOx sensor signal, and the signal isolation that two-way CAN passes through photoelectric isolation module 4 is sent to
Data processing module 5.Photoelectric isolation module adopts high speed optocoupler TLP521-4, makes the voltage pulsation in bus not interfere with control
Module, photoelectric isolation module output circuit is as shown in Figure 4.
Control module 5 adopts freescale companies microprocessor of 16 bit MC9S12XDP512, aboundresources in piece, with 5
The CAN controller of road independence, can be met using single chip mode and be required, it is to avoid external bus interface, enhance system
Reliability.The processor has XGATE modules, can undertake the process task of CPU ancillary equipment, supports more certainty
Interrupt processing, it is to avoid execution information receive send, communication conversion when Core Feature and interrupt processing conflict.
Data processing module 5 receives two-way CAN data, and unloading enters two-way CAN data buffering modules TJA1050, electricity
Road is as shown in Figure 5.The concrete length of receiving data can be assisted according to switching rate, the baud rate of CAN and CAN application layer
Depending on view, its effect is mainly the data stacking that different band of cancellation protocol modular converter baud rate is come, and for data processing
With the data segment that verification provides complete application layer protocol.
This device data processing detailed process is as follows:
(1)Data are read in from CAN interface 2,3;
(2)Data In about NOx concentration are proposed from the data read in;
(3)In is converted into into NOx concentration Data, the number range of Data=In × 0.005-200, Data is [0,1500];
(4)If Data>1500 or Data<0, send warning;
(5)By 4-20mA output circuit output currents.Using output valve OUT=65535 during 16 conversion circuits ×
Data/1500;
It is as follows that this device redundancey data fault processes detailed process:
(1)Data are read in from CAN interface 2,3;
(2)Obtain NOx concentration data Data1 and Data2 that two passages are processed;
(3)If Data1<0 or Data1>1500, send warning;
(4)If Data2<0 or Data2>1500, send warning;
(5)If | Data1-Data2 |≤E, the data of CAN interface 1 are exported;
(6)If | Data1-Data2 |>E, E are given threshold, and the first three data obtained using CAN interface 1 is entered
Row cubic equation interpolation, obtains prediction data value Data1* of this CAN interface 1;Obtained using CAN interface 2
First three data carries out cubic equation interpolation, obtains prediction data value Data2* of this CAN interface 2;
(7)| Data*1-Data1 | and | Data*2-Data2 | is calculated, taking the minimum channel data all the way of both errors is
True value;
(8)If | Data*1-Data1 |>E, and | Data*2-Data2 |>E, sends warning, and flow process is as shown in Figure 3.
4-20mA output conversions adopt AD421 chips, and it is a kind of monolithic high-performance digital to analog converter (DAC), by electric current
Loop service, 16 position digital signal serial inputs, 4-20mA electric currents output meets the requirement of industrial control standard signal output, can
Remote industrial control is preferably realized, circuit is as shown in Figure 6.
In addition the noise in system mostlys come from power supply, and processing of circuit is filtered to power supply, and power supply is reduced as far as possible
Noise.The utility model using muRata companies combined electrical source filter BNX002, have in the range of 0.5M-1GHz compared with
High insertion loss, can simultaneously suppress power line and ground wire noise.
Claims (1)
1. a kind of CAN for NOx sensor turns the data-signal conversion equipment of 4-20mA, including NOx sensor (1),
First CAN interface (2), the second CAN interface (3), data processing module (5), the first photoelectric isolation module (4),
Two photoelectric isolation modules (6), 4-20mA output circuits (7), it is characterised in that:NOx sensor (1) exports digital quantity signal, Jing
Signal isolation of the two-way CAN by photoelectric isolation module (4) is crossed, data processing module (5), data processing module is sent to
Signal be sent to 4-20mA output circuits (7) through the second photoelectric isolation module (6) and be converted into 4-20mA analog signalses;
The photoelectric isolation module adopts high speed optocoupler TLP521-4, data processing module to adopt the microprocessor of 16 bit
MC9S12XDP512;
Data processing detailed process is as follows:
(1.1) data are read in from CAN interface 2,3;
(1.2) data In about NOx concentration are proposed from the data read in;
(1.3) In is converted into into NOx concentration Data, the number range of Data=In × 0.005-200, Data is [0,1500];
(1.4) if Data>1500 or Data<0, send warning;
(1.5) by 4-20mA output circuit output currents, using output valve OUT=65535 × Data/ during 16 conversion circuits
1500;
Redundant data troubleshooting detailed process is as follows:
(2.1) data are read in from CAN interface 2,3;
(2.2) NOx concentration data Data1 and Data2 that two passages are processed are obtained;
(2.3) if Data1<0 or Data1>1500, send warning;
(2.4) if Data2<0 or Data2>1500, send warning;
(2.5) if | Data1-Data2 |≤E, the data of CAN interface 1 are exported;
(2.6) if | Data1-Data2 |>E, E are given threshold, and the first three data obtained using CAN interface 1 is carried out
Cubic equation interpolation, obtains prediction data value Data1* of this CAN interface 1;Before being obtained using CAN interface 2
Three data carry out cubic equation interpolation, obtain prediction data value Data2* of this CAN interface 2;
(2.7) | Data*1-Data1 | and | Data*2-Data2 | is calculated, it is true to take the minimum channel data all the way of both errors
Value;
(2.8) if | Data*1-Data1 |>E, and | Data*2-Data2 |>E, sends warning.
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CN106523079A (en) * | 2016-11-29 | 2017-03-22 | 深圳万发创新进出口贸易有限公司 | Disinfecting and exhausting device for internal combustion engine |
CN112332844B (en) * | 2020-11-03 | 2022-11-22 | 中国航空工业集团公司西安航空计算技术研究所 | Sensor data processing system |
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