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The Design and Application of Conductance Rate Virtual Instrument

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1. mol dm and 0 0031mol dm The real time acquiring data is shown in Fig 5a Calling the built in program to process the testing data and the dissociation constant of K 1 817 10 is obtained Comparing to the reference Wu 2000 the relative error is 0 94 and the relative errors of handwork are mostly more than 4 The VI of system is applied in the alkali NaOH titration with the strong acid 0 1000mol dm Precisely taking the 2ml solution of sodium hydroxide the titration experiment is performed three times with the hydrochloric acid of 0 1000mol dm By the corresponding built in program of data processing the three hydrochloric volume 2 02ml 2 04ml and 2 02ml of being expended are obtained and the RSD is 0 57 The panel of data processing is shown in Fig 6b In the same experiment the results of manual testing are 2 01ml 2 05ml and 2 04ml The RSD is 1 02 The above applications indicate that the VI system not only has function of real time data acquiring displaying storage but also realizes different the analyzing and processing of data reporting of result according to the different testing task moreover the veracity and repeatability of data processing result are higher than the results of manual data processing On the real time acquiring panel of VI for example Fig 3a 4a 5a the real time curve and the digital value are displayed and the needle meter that real time display the value of testing is placed on
2. concentration of tested matter are obtained automatically 330 4 The results of application and discussion The VI of conductivity is applied in the detection for simulation of moving water The real time conductivity value and time is shown in Fig 3a When the testing value is out of the range set by the user the conductivity value and the corresponding time will be recorded and the system will give an alarm automatically Obviously the VI system also can be applied to the water detection of industrial and environmental occasion VI stores the conductivity and time in the format of text or binary system which is convenient for the user to further process the data The VI system is applied in testing the rate constant of second order reaction When the temperature is 298 C the concentration of NaOH is 0 0104mol dm and CH3 CH OOCH gt CH is 0 0092mol dm the conductivity and time are shown in Fig 4a The testing data is processed by the built in program and the constant of second order reaction is 6 944mol dm min Comparing to reference value Wu et al 1995 the relative error is 1 28 and the correlation coefficient of line fitting is 0 9996 And for the same experiment relative errors of most results obtained by handwork are more than 5 This VI system is applied to determine the dissociation constant of acetic acid and to test six samples e g 0 1000 mol dm 0 0500 mol dm 0 0250 mol dm 0 0125 mol dm 0 0062
3. the top left corner which improve the lifelike and vivid image of VI The knob of range choice on the top right corner of VI is matched with the testing range of conductivity meter The emulational knob of channel choice is matched with the channel of DAQ board When the user chooses a channel the operating panel of VI will real timely display the data of corresponding channel This function can meet need of multi channel determining synchronously in the research and production the DAQ board has 16 single channels or 8 double channels The operation of knob is operated only by clicking mouse and this offers the more convenience to users The VI can be packed as a stand alone application by using the Application Builder of LabVIEW and the application can run separately from the LabVIEW just like other the executable programs If the 33 conductivity meter connected with computer is different the VI can work after just adjusting the circuit which improves the practical application of VI Obviously when the traditional conductivity meter is used to perform the other testing task the system can be upgraded from the traditional apparatus to high performance VI and intelligently performs the testing task by only changing some LabVIEW programs according to the principle of testing and special requirement To sum up the conductivity VI based on LabVIEW 8 0 Express is developed with a computer connecting to the general conductivity meter homemade ad
4. LabVIEW has not been reported yet The VI of conductivity meter developed by authors is developed in graphical programming language LabVIEW 8 0 Express which not only has advantages of easy expandability friendly interface easy operation et al but also realizes the multitask measuring real time The result is satisfying 2 Structure of testing system The diagram of test system is showed in Fig 1 The system consists of hardware and software in general The hardware deals the amplification filtering acquiring and display of analog signal As the central part of VI the software realizes the driving of DAQ board data display real time designing of VI panel analysis and processing of data generation of result report and so on Conductivity meter gt Adjusting circuit gt DAQ board gt C gt LabVIEW Fig 1 The structure diagram of the system Conductivity meter The type of conductivity meter is D307 which has function of output of direct analog signal The direct analog signal which expresses the value of conductivity is automatically acquired by computer with the DAQ board after being pretreated by adjusting circuit The other conductivity meter which has function of direct signal output can be acceptable as well Adjusting circuit The adjusting circuit consists of differential amplifier which is mainly made of a low drift operational amplifier Op07 and first order active filter which is mainly made of a high gain operat
5. MATCH MATCH Commun Math Comput Chem 60 2008 325 331 Communications in Mathematical and in Computer Chemistry ISSN 0340 6253 The Design and Application of Conductance Rate Virtual Instrument Based on LabVIEW 8 0 Express LI Jiang yuan LI Yuan wen GUO De peng College of Chemistry and Chemical Engineering China West Normal University Nanchong 637002 China Received December 17 2007 Abstract The conductance rate Virtual Instrument is developed based on LabVIEW 8 0 Express and applied to multitask testing by using the easy expandability of Virtual Instrument The result of application indicates that this test system not only has advantages of friendly interface easily operating a computer for multipurpose easy expandability of function etc but also has function of real time data acquisition data storage data display and data processing avoids personal error of data record and data processing by handwork in process of testing improves the veracity and the automaticity and expands the function of traditional instrument 1 Instruction As a common electrochemical testing apparatus the conductivity meter is widely used The testing data of traditional conductivity meter is obtained by handwork or recorder Obviously the analysis and processing of testing data obtained by traditional conductivity meter can only be done by manual work and it is difficult to avoid man made error which may restrict the application of conductiv
6. an be realized The operating panel of data acquiring is shown in Fig 4a and the host program is in Fig 4b The Event Structure of host program is associated with corresponding button of operating panel Clicking the button on panel and the host program will call correlative Event Structure The While Structure of outermost program performs the continually running until the testing ends te _ 7 a 7 g PH Disabled o g T oo0oo0ooocooocoooocoocoooooooooaooooooaoooaooooaooo0oooooadL Fig 4a Operating panel of data acquisition Fig 4b Main program of determining rate constant of second order reaction 3 5 The VI for determining dissociation constant of weak monoacid by conductivity 329 The dissociation constant of weak monoacid is obtained by testing conductivity of different concentration weak acid solution As to a concentration solution the VI system should determine whether the testing completes and inform the user to change the testing sample The testing panel is Shown in Fig 5a and the block program is in Fig 5b The methods of determining whether the testing has completed is to detect five times in a time interval to a concentration sample and if every RSD is not higher than 0 01 the VI system will take the testing as completed and inform the user to change testing sample with the light of change sample The mean of five testing value is saved as final testing value in file automatically The concentration o
7. f solution and the corresponding conductivity value are processed by linear fit At last the dissociation constant of weak monoacid is determined by the slope of line Operating Panel of Determining Dissociationconstant of Weak Acid Condantance yuS cm Cursor fie o Bal ol curve J eins West Neral Universit Fig 5a Operating panel of determining dissociation Fig 5b Block program of determining dissociation constant of monoatomic weak acid constant of monoatomic weak acid 3 6 The VI of conductometric titration The conductometric titration is broadly applied in electrochemical analysis The host program of VI of conductometric titration based on the VI conductivity is shown in Fig 6a and the data processing panel is in Fig 6b The two temporary files are created to save the conductivity value and the titration volume automatically in the host program During the data processing the user is informed to input the ratio of titration matter and the matter to be tested Joop opoooDoOoOooDoooooD oo0oo0o0oo0oo0ooo0o0o0og0oo0oo0o0o0o0 z as R 1 0 11 P Data Processing Panel of Conductivity Titration alue Change ir i k Titrant J2 02 Tested Matter 0 1008 mo voum a f7 x conduc a2 r 1 1 i 1 1 0 Ts 20 25 Volume mL Fig 6a Main program of operating panel of Fig 6b Data processing panel of conductivity conductivity titration titration Then the volume of end point and the
8. ional amplifier CA741 And they jointly realize the analog signal amplification and filter which could make the gain value reach as high as possible but not exceed the input range of DAQ board Thus not only the precision and accuracy of testing is enhanced but also the data of testing can be not lost DAQ board DAQ board PCI2005 is produced by Beijing Art Science and Technology Development Corp Ltd And it is a 16 bits A D analog digital converter based on PCI bus It can acquire the data through 16 single channels or 8 double channels It has an input resistance of 100MQ a sampling frequency of 200KHz and a range of analog input of 10V Inserting DAQ board into built in PCI plug of computer and calling the corresponding driving program the real time data acquisition is obtained with LabVIEW programming For the other type DAQ board the data acquisition can be realized by the same way plus a corresponding driving program Computer it has an available PCI plugs 256M memory or more 220M hard disk or more 486 DX or more advanced CPU 600x800 or more resolution The general computer is acceptable 3 The design and realization of LabVIEW 8 0 Express In accordance with the practical application of conductivity and configuration of VI 327 developed by authors the VI tracks and acquires the analog direct signal outputted from the outlet that is used to connect with recorder Calling the driving program to do the A D converting and cha
9. ity meter in a sense Wu et al 1998 Wang et al 2001 Virtual Instrument VI expands functions of traditional apparatus and improves traditional apparatus intelligently The technology of virtual instrument not only improves the functions of real time veracity and automatization of testing apparatus but also realizes single computer for multitask Liu et al 2005 LabVIEW is a graphical programming language developed by National Instruments and is widely applied in instrument controlling automatic testing processing data and et al It is the excellent software to develop VI LabVIEW has advantages of friendly interface vivid panel of Virtual Instrument and programming mode of flowing which greatly enhances the efficiency of developing VI LabVIEW is more and more widely applied in different fields of instrument measuring and controlling Lei et al 2004 Zhang et al 1998 Correspondence Li Jiangyuan College of Chemistry and Chemical Engineering China West Normal University Nanchong 637002 P R China E mail lijy5649 yahoo com cn 326 The research about conductivity meter connected to computer has been reported in recent years Kang et al 2002 Kuang et al 2004 but the software is mostly developed in text based programming language for example C Turbo Pascal VB and so on The text based language has disadvantage of long developing periods difficult maintenance and difficultly expanding The VI of conductivity meter based on
10. justing circuit DAQ board The functions such as data acquiring automatically real time displaying automatically processing of testing data and obtaining the report of result immediately are realized The examples of application indicate that the VI not only realizes a computer of multipurpose but also avoids the complication and the manual error during the recording and processing of testing data and further improves the veracity and repeatability of testing result At the same time the practice shows that using the LabVIEW 8 0 Express to develop the VI also has the advantages of high efficiency friendly interface easy operating and wide expandability of functions etc 5 Acknowledgment The authors are grateful to the important research item of China West Normal University 200201 and Sichuan provincial Department of education 2005 198 for financial support Reference 1 ZR WU D W QI Y T WANG On line Conductivity Titration Technique Analytical Laboratory 17 1998 No 5 90 93 2 Y T WANG W Q ZHANG R B HOU Measuring Rate Constant of Saponification of Ethyl Acetate with On line Electric Conductivity Instrument Journal of Guangxi Normal University 19 2001 No 3 50 54 3 J Y LI Z R LIU Y C WANG Virtual Instrument of Electrochemistry Based on LabVIEW 7 Express Computers and Applied Chemistry 22 2005 No 10 918 920 4 Z S LEI LabVIEW Practical and Technologic Student Edition 7 0 Express China Railway Publishi
11. m E 3 H Low limit 355 Low alarm gt Dm Fig 3a Operating panel of on line measurement Fig 3b Block program of on line measurement value with the top limit and low limit set by the user if the real time value is out of the range of top and low limit the warning lighter and the warning sound are switched on and the measuring VI saves the value of conductivity automatically This VI also saves the conductivity value exceeding a range and the corresponding time according to the user setting in advance At the same time the user can set the sampling interval for long time real time measure continually 3 4 The VI of determining rate constant of second order reaction in electric conductivity The data processing of second order reaction rate constant is complicated especially when the initial concentrations of two different reactors are not equal In accordance with the principle of determining rate constant for second order in electric conductivity Fu 2004 using the powerful build in function of LabVIEW data analyzing and processing each data processing program is developed into corresponding sub program based on which the module of program for determining the constant of second order reaction is further built Importing the module of sub program into the system of conductivity VI and the data acquiring and processing automatically for determining the constant of second order reaction with electric conductivity c
12. ng House Beijing 2004 5 Y ZHANG F L LONG Compare of Three Newest Software in System of Test and Control Control and Instruments in Chemical Industry 25 1998 No 3 25 27 6 X Y KANG H LIU Quantitative Determination of Potassium by On line Conductivity titration Technique Journal of shanxi Normal University 30 2002 140 141 7 L KUANG L WU Studying Kinetics of Saponification of Ethyl Acetate with Computer College Chemistry 19 2004 No 4 39 43 8 National Instruments Corporation LabVIEW User Manual Edition 20 1 2003 9 Fudan University Physical Chemistry Experiments Third Edition Higher Education Press Beijing 2004 10 Z S WU Z YAN Instructor of Physical Chemistry Experiments Northeast Normal University Publishing House Changchun 1995 11 Wuhan University Analytical Chemistry Fourth Edition Higher Education Press Beijing 2000
13. nging the voltage signal into digital value of conductivity at last the real timely value is expressed by programming of LabVIEW For the different application the real time display image and the method of data processing are different So the LabVIEW program of VI includes a common program which is composed of a DAQ board driver and a real time data displayer and a data processing and analysis LabVIEW program which performs the corresponding different testing task 3 1 The design of DAQ board driving program Because this testing system uses a domestic made DAQ board LabVIEW can not call the driving program automatically and needs to call the Function gt Advanced gt gt CLF Call Library Function Node National 2003 to realize the data acquiring The driving program is realized by Stacked Sequence Structure that consists of seven subprograms The seven subprograms independently perform DAQ board parameter assigning equipment initializing A D equipment activating obtaining the result of A D converting adjourning A D equipment releasing the A D and closing the equipment Details of this driving program are not provided in this article 3 2 The design of data acquiring and real time displaying program The data acquiring and displaying program is showed in Fig 2 and it mainly performs the function of data acquiring the converting of signal voltage to conductivity value real time expressing of conductivity value and so on The voltage signal acqui
14. red from DAQ board is converted to conductivity value by function of Formula Node in which the relation of voltage and conductivity is pre adjusted The function of Case Structure performs the range choice matching to corresponding relation of voltage and conductivity value The graph of conductivity value G and time t is real time presented by function of XY graph The outer Ja 3 0 6 pe E structure of While Loop Hi of program ensures the continually running of testing and the sampling interval also can be set by users The above two program they are directly Fig 2 Program of real time display of data acquisition called as sub program in following program act as general program in this testing system They respectively perform driving of DAQ board and converting of analog signal to conductivity value For the different testing task by adjusting the corresponding data processing program of LabVIEW to above two general programs the testing task can be performed conveniently 3 3 The on line measuring system of conductivity The operational panel of on line measuring system is showed in Fig 3a and the corresponding block program in Fig 3b In this program the conductivity value acquired by conductivity VI the top limit and low limit of conductivity value set by the user are bundled and are expressed by the function of Waveform Chart together Comparing the real time acquired 328 EE M False vb E Top alar

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