Oscilloscope Control with PC
Contents
1. Fig 5 The signal txt file with some random numbers forming a random signal In Fig 6 we can see the graphical user interface running and acquisitioning a square waveform The plotted signal is generated with the oscilloscope internal generator with plugging the oscilloscope probe in the calibrate input The measured signal has more samples but we acquisitioned only 256 samples signal information because the RS 232 interface has a buffer of 512 samples For more samples we have to make multiple acquisitioning 38 Issue 3 Volume 3 2009 Disconnect POS Y POS II VOLTSIDIV VOLTS DIV II ah c nv d TIME DIV Read VVavet ll Write Wawvef 11 Read VVavef Write Wavef Fig 6 The graphical user interface for the HAMEG HM 407oscilloscope running when acquisitioning a square signal IV THE NI OSCILLOSCOPE COMMAND The NI oscilloscope differs more from the HAMEG oscilloscope It s not a stand alone oscilloscope it only a card that can be used just connected to a PC this way the drivers are compulsory so National Instruments provided them The drivers were used and worked very well The oscilloscope card is in a PXI chassis Fig 7 This chassis 1s connected to the PC via the MXI interface which has speed up to 132 MB s Our chassis is the NI PXI 1044 with 14 slots Fig 7 NI PXI 1044 chassis for acquisition cards INTERNATIONAL JOURNAL OF COMPUTERS AND COMMUNICATIONS2. The chosen oscilloscope is the NI PXI 5412 Fig 8 This oscilloscope is traditional National Instruments equipment It uses the NI SCOPE driver Musis a Fig 8 NI PXI 5412 oscilloscope from National Instruments The Front Panel of the NI PXI 5412 oscilloscope command made in LabVIEW is shown in Fig 9 As we can see we have the resource name which shows the card number in the PXI chassis Two vertical adjust dials for each channel and a horizontal adjust dial We have two Waveform Graphs which shows the signals at each channel The Block Diagram is shown in Fig 10 As we can see we have a While loop Its timing is set to 100 ms Outside of the loop is the initialize and close VIs ending everything with simple error handler We have one horizontal adjust VI and to vertical adjust VIs with two read VIs for the two channels from the oscilloscope channel 0 and 1 At the second channel we have a Bessel filter We used a Build Array VI and Shift resource name Horizontal adjust Vertical adjust CHO 1321 119 o_o i Issue 3 Volume 3 2009 Registers to make the static Waveform Graph dynamic otherwise we would see a graph just after the While loop ends CHO 7 resource name g DAQ 8 4 Vertical adjust CHO Amplitude CHI Pto veritcal adjust CH1 0 5 E y MAL x 1 iF 4 0 z 3 7 9 3 E 2 10 o E Horizontal adjust 0 2 4000 6000
3. Company Timisoara Romania The direct customers of Timteh Ltd was Rada Electronic Industries Tel Aviv Israel and Elbit Systems Ltd Haifa Israel Activities development and implementation of software for testing Boeing 737 Boeing 777 DC 10 and Concorde airplane electronics units on the specific Automatic Test Equipment ATE development and implementation of hardware for digital video recorder collaboration with Metrys Gmbh Germany regarding Hardware and Software solutions for Water Meters Heat Costs Allocators Transit Time Ultrasonic Liquid Flow Meters AMR Automatic Meter Reading and RFID He has over 30 papers 2 books and 8 grants Interests Electronic Design Automation Methods and Implementations for Ultrasonic Measurement and Testing Programmable Logic Microcontrollers and Microprocessors Automatic Test Equipments Software for applications Assoc Prof Ioan Lie PhD is at Applied Electronics Department Faculty of Electronics and Telecommunications Politehnica University of Timisoara Romania Mircea Babaita is lecturer in the Faculty of Electronics and Telecommunications Politehnica University of Timisoara Romania He was born in Or tie Hunedoara Romania in July 18 1964 He had 6 weeks scholarship at University of Strathclyde Glasgow Scotland 2000 2 weeks scholarship at University of Mannheim Germany 2002 Activities development and implementation of hardware and software for regar
4. S Baglio N Pitrone Teaching Advanced Technologies to Undergraduates Engineering Education EE 08 5th WSEAS IASME International Conference 2008 pp 360 365 1 2 3 4 2 6 7 8 9 10 11 12 15 14 40 Issue 3 Volume 3 2009 Roland Szab is a Master student in the Faculty of Electronics and Telecommunications Politehnica University of Timisoara Romania He was born in Timisoara Romania in April 14 1986 He is an electrical engineer since 2009 with LabVIEW Basics I amp II Certificate from National Instruments Hungary 2009 with Software Quality Engineer certificate from Continental Automotive Romania 2009 He is a Hardware Engineer at Continental Automotive Romania located in Timisoara He is research laboratory responsible in the Faculty of Electronics and Telecommunications Politehnica University of Timisoara Rom nia He had summer job also in Alcatel Lucent located in Timisoara Romania He has 5 papers Areas of interest robots creating computer interfaces for electronic equipments servers web programming Eng Roland Szabo is a Hardware Engineer at Continental Automotive Rom nia Aurel Gontean is professor and vicedean in the Faculty of Electronics and Telecommunications Politehnica University of Timi oara Rom nia He was born in June 26 1961 He had 3 months scholarship at Central Lancashire University Preston Englan
5. 4 F F Tus ml a LI EI Ur m mal Foe gu HI 10 al H p V ot 4 ar 4 EE FHI 779 TELE AF E Ek n d sa EP HI H TP TE Fari chee ik Hir i E EE HII LE TM I t r TU LL berari E n LU 3 EP HM AT TNT M x z 1 T TNI i c F ETH Fig 4 The HHD Serial Monitor program obtaining SPCI commands from and existing program TABLE I shows the used SCPI commands These commands are obtained from the user guide or from an existing program using the Free Serial Monitor program We obtained them from the user manual because we couldn t find an existing program for our oscilloscope INTERNATIONAL JOURNAL OF COMPUTERS AND COMMUNICATIONS TABLE I USED SCPI COMMANDS Command Description AUTOSET AUTO SET function will be carried out YzPOS w Sets Y 1 2 POSITION settings XPOS w Sets X POSITION settings CHz b Sets CH1 2 settings like amplitude TBA b Sets TIMEBASE settings STRMODE b Delivers STORE MODE RDWFMz ww READ WAVE FORM 1 2 WRREFz ww WRITE REFERENZ 1 2 RMO Exit REMOTE mode The functions used for write and read data from the serial port are fwrite and fread For example the Autoset button has the following code function autos Callback hObject eventdata handles cmdb double AUTOSET b 13 10 fwrite handles obj1 cmdb b bl2fread handles obj1 3 Every button h
6. and edit text axe indicators were used INTERNATIONAL JOURNAL OF COMPUTERS AND COMMUNICATIONS Issue 3 Volume 3 2009 ae as ee LAN AUTRET Pise o Da ca HT 0 END CT vPO05 1 ANALOG O DIGITAL SCOPE HM407 VOLTS EHV 3 4 CHI DUAL cH EB ee a 2 ad Wr ug LI THLOMETK 2 ADANAN 27 5 GEM pereant REPT CHi HOR In 40 MHz iNT CHI m er File Edit view Layout Tools Help sg ir ane PIME Paap Ra ORME CheckBox H Button Group 5 m W Activex Contral FE ESSEC see Fig 2 Front panel creation of the oscilloscope in MATLAB This window can be accessed when the guide command is introduced to the command prompter 34 INTERNATIONAL JOURNAL OF COMPUTERS AND COMMUNICATIONS As we can see we have a Connect button for connecting the computer to the oscilloscope This buttons sends the command which puts the equipment in remote mode During this time the physical buttons from the oscilloscope are not functional it pressed they make an error beep An LED indicator on the oscillo
7. bit is not activated manually on the oscilloscope the saving of a signal will not work and an error beep will be received C The Code behind the buttons In this section the code behind the buttons is explained Every SCPI command needs to be ended with carriage return CR 0D 13d There are exceptions too some of them needs only CR and other CR and LF depends on the SCPI command These SCPI commands can be obtained from the oscilloscopes user manual or from an existing program with the HHD Free Serial Monitor program Fig 3 and Fig 4 With this program we can obtain the SCPI commands that the existing program uses Device CO File Edit View Tools Window Help DFAS 2 0860 0 m Reque D ce 0 m Ed Ordi Function Direct Data P Status Dal lt gt Seles Read Requests lt gt Write Requests lt gt lt gt Ready RTS CTS DSR DCD DTR RI Fig 3 The HHD Serial Monitor program configured BUT Data Fas Mien wHh aarp Fens teria Peet erim ink A fem pie ume DD a 7 a Paget rares aena Sae Fan nis ui aae 1 il TER E T T m I avs T PA x r dee 299 ee prd Bi PEL F T Vigne 29 04 DET PTh PA L2 CODO pacc ul BG ook Ex m ins 281 ud h GE jaj DODO pcne Port laur 7
8. f 3 0 4 2000 8000 0 5 1 i i i 0 20 40 60 80 100 120 100 10000 STOP Fig 9 The Front Panel of the NI PXI 5412 oscilloscope program made in LabVIEW Fig 10 The Block Diagram of the NI PXI 5412 oscilloscope program made in LabVIEW V CONCLUSION These days the instruments have simple SCPI commands where no need for binary calculation is Some instrument s vendors provide even drivers where some functions gather the SCPI commands with the binary values and the user just calls the functions and enter decimal values As we saw almost any instrument can be programmed as the user wants and in any programming language The datasheet needs to be analyzed well and with a little binary calculation and some programming trick almost everything can be done The goal was achieved We wanted to program an instrument and we needed some functions that are not possible without a computer like signal sending to the oscilloscope or saving from it Further enhancements would be to make a button for every setting on the oscilloscope maybe try program it in other INTERNATIONAL JOURNAL OF COMPUTERS AND COMMUNICATIONS programming language like C and make an official driver with all function of the oscilloscope so this way programmers will not have to do so many binary calculations and read all the datasheets The whole idea of this oscilloscope programming 15 that we wanted to see if we are capable of programming a
9. have 10110006 88d and for reference memory 2 we will have 100110005 152d This way we don t need to push the reference button manually all the time and stop the program After it we need to lot de received data to the axe so the program section will be function rdwfl Callback hObject eventdata handles cmdi double STRMODE i 16 13 fwrite handles objl cmdi 1 il fread handles obj1 3 cmdj double RDWFM1 jer D fwrite handles objl cmdj j 1 jl fread handles obj1 267 1 1 for kz12 207 INTERNATIONAL JOURNAL OF COMPUTERS AND COMMUNICATIONS V 1 J1 k 1 1 1 plot For writing a signal to the memory is quite similar to reading it The used SCPI command is WRREFz ww where z is the number of channels or 2 and the first w word is the offset and the second is the length The signal is written by some numbers in one colon in the signal txt file The function should be the following function wtwfl Callback hObject eventdata handles cmdmezdouble STRMODE 2 m 88 13 fwrite handles objl cmdm m mi fread handles obj1 3 load ascii cmdnzdouble WRREF1 0 4 0 1 signal 13 fwrite handles objl cmdn n nl fread handles obj1 3 The signal it s transposed with signal it is more simple to write values in a colon in a txt file than in a row The file must contain exactly 256 values Fig 5 P signal Notepad File Edit Format wiew Help
10. timebase For amplitude we have 14 values between 1 mV DIV and 20 V DIV this way 1 mV DIV means 1 but we need to send 16 and 20 V DIV means 14 but we need to send 29 so we have to add 15 to every value Same thing for TIME DIV but we have 26 values between 1 us DIV and 0 5 s DIV so we need to add 3 to every value Maybe a little more complicated is the reading of the waveforms the used SCPI command is RDWFMz ww where z is the number of channels or 2 and the first w word is the offset and the second is the length The offset we will set to 0 so the first two bytes are 00 and 00h The length we will set to 256 samples 256 points the serial has a 512 sample buffer 256 0100h we split the word in two bytes and we get 01A and 00A after all we need to send it in reversed order so 00 and 01 4 All the numbers from the offset and length in reversed order in decimal and with CR termination character 15 000113 Where we plot the information from the 12 sample because these samples in the start are information about the waveform but the waveform data starts from 12 and ends at 267 For this signal acquisition to work we have to be careful with the STOR MODE bits using the STRMODE b SCPI command D7 REF2 REFI D5 PRE TRIGGER 011 0 and D2 D1 STOR MODE 000 REF This way for signal acquisition we need no reference memory so we have 110005 24d for sending signals to reference memory 1 we will
11. INTERNATIONAL JOURNAL OF COMPUTERS AND COMMUNICATIONS Issue 3 Volume 3 2009 Oscilloscope Control with PC Roland Szab Aurel Gontean Ioan Lie Mircea Babaita Abstract In this paper two different oscilloscope control methods are presented The first method is the classic method to send the SCPI commands via RS232 serial interface The second method is to use the LabVIEW divers The first oscilloscope is the HAMEG HM407 which has its control program implemented in MATLAB The second oscilloscope is the NI PXI 5412 with the control program in LabVIEW The second control program is much faster and mare simple but with the classic method we can configure more and have a better control over the oscilloscope The classic method is also general because it can be controlled any oscilloscopes and equipment even if they have no driver In the first method the driver is made in the second method a driver is used Keywords Communication equipment control equipment driver oscilloscope protocol remote handling serial port I INTRODUCTION HIS paper presents the creation of an oscilloscope driver To test the driver the HAMEG HM 407 40 MHz 100MS s cathode ray tube oscilloscope Fig 1 is connected with the PC to be controlled via the RS232 serial port The oscilloscope is an analog digital oscilloscope It has an RS232 serial port and a microcontroller with implemented SCPI Standard Commands for Programmable Instruments com
12. as similar code to this example obj is set to COMI the first serial port installed on the computer but it can be set to any COM port desired with the following command handles objl serial COM1 The information is sent decimal Comments are generated automatically by MATLAB which can be cleared Here the SCPI command is AUTOSET The command need to be ended with carriage return CR ODA or 13d and line feed LF OAA or 10d too The AUTOSET command is concatenated with the carriage return and line feed bits The number 3from the fread function 1s the number of bits read Modifying this function we can make the functions for all buttons just by reading the specific SCPI command from datasheet and being attentive to some bits The Connect button has a similar function but no SCPI commands are used only sending the 20 4 32d and the CR termination character The serial port is opened with the fopen and closed with fclose functions and set to its default values baud rate 9600 data bits 8 parity none stop bits 1 flow control none fopen handles objl fclose handles obj1 The serial port is activated with the following command set handles objl FlowControl hardware The ON OFF indicator 1s commanded where needed with the following commands 36 Issue 3 Volume 3 2009 sect handles sts String ON set handles sts String OFF Where sts is the indicator s identifier and String is th
13. command and for horizontal position with the XPOS w SCPI command For the amplitude the used SCPI command is CHz b where z in the number of channel or 2 and 5 is the value in byte There are 4 bytes for other settings to the channel and 4 bytes for setting the amplitude D7 GND D6 AC D5 INV D4 ON D4 are the setting for amplitude between 00005 11015 0d 13d All bits can be 0 logic but the ON bit must be at 1 logic so the number we need to send are between 100005 111015 16d 29d This way the slider s value is set to 22 and the minimum value to 16 and the maximum value to 28 The same thing can be made for the channel 2 but with the CH2 b SCPI command and a similar function will work for the timebase but with the TBA b SCPI command where A is the A timebase because this model has no B timebase The program for the amplitude is the following function vdivl Callback hObject eventdata handles voldlzget hObject Value ce ndfedoublet oHlet 7 ftelroundTvolol 13 fwrite handles objl cmdf f fl fread handles obj1 3 37 Issue 3 Volume 3 2009 The program for the timebase is the following function tdiv Callback hObject eventdata handles timedzget hObject Value cmdhzdouble TBA h round timed 13 fwrite handles objl cmdh h hl2fread handles obj1 3 For pop up menu the programming is a little more complicated because we ne exact amplitude and
14. d VLSI Design oriented 1996 a 3 months scholarship at Fachhochschule Wiesbaden Germany Programmable Logic Design oriented 1995 a 3 days FPGA Workshop Texas Instruments Germany 1993 He is an IEEE member since 1999 Activities Invited Professor DH Loerrach Germany EU Expert appointed grant reviewer in Bulgaria Initiates the Remote Access Electronic Lab in Electronics Faculty Timisoara Romania International Program Committee member Programmable Devices and Systems conferences IFAC National reviewer for Romanian grants Workshops and trainings dedicated to Digital Electronics Fundamentals and Microcontrollers at Solectron Timisoara Workshops and trainings dedicated to Digital Electronics Fundamentals and Microcontrollers at Siemens VDO Timisoara IEEE Member 1994 Member in the x TEAM research team Texas Instruments Europe 1993 Appointed lecturer for Texas Instruments FPGA Workshops and Seminars in Romania He has over 70 papers 5 books and over 20 grants Interests VHDL FPGA C NET programming Prof Aurel Gontean PhD is a PhD advisor in the Faculty of Electronics and Telecommunications Politehnica University of Timisoara Romania Ioan Lie is associate professor in the Faculty of Electronics and Telecommunications Politehnica University of Timisoara Romania He was born in Recea Brasov Rom nia in October 28 1961 Other jobs Engineer at Electrotimis Ltd Timisoara Timteh Electronics Ltd
15. ding DSP Utilization for MCC Motor Drives development and implementation of hardware and software for E learning Distance Interactive Practical Education in Power Electronics He has over 50 6 books and over 20 grants Interests Digital Logic Microcontrollers and Microprocessors Power Electronics Motor Drives Fuzzy Logic Lect Mircea Babaita 15 at Applied Electronics Department Faculty of Electronics and Telecommunications Politehnica University of Timisoara Rom nia
16. e parameter that is changed and after that is the value ON or OFF With this command almost every parameter can be changed like size or position The whole initialization program is the following function HM407 OpeningFcn hObject eventdata handles varargin handles objl serial COM1 handles output hObject guidata hObject handles function varargout HM407 OutputFcn hObject eventdata handles varargout i handles output function 1 CreateFcn hObject eventdata handles function con Callback hObject eventdata handles 1 1 set handles objl FlowControl hardwa re a 32 13 fwrite handles objl a al fread handles obj1 3 set handles sts String ONTI The Disconnect button is made similar but it uses the RMO remote 0 SCPI command and the serial port is closed with the fclose function function discon Callback hObject eventdata handles cmdz double RMO z 13 10 fwrite handles objl cmdz z zl fread handles objl 3 set handles sts String fclose handles objl YOFE 3 For the horizontal position setting first we read the value of the slider with the following command ypl get hObject Value Then we use the YZPOS w SCPI command where z is the number of channel 2 and w is the distance in word The only problem is that the oscilloscope is like a coordinate system and it has positive and negative position The goal wa
17. e used Because sliders were fuzzy a more accurate solution was needed to set exactly the timebase and the amplitude this way pop up menus were used For timebase between 1 wus DIV and 0 5 s DIV for amplitude between 1 mV DIV and 20 V DIV The values can be set exactly For the timebase and amplitude both controls are functional for exact and for fuzzy setting of the signal For saving the signal form the oscilloscope two buttons are used Read Wavef I for CH I and Read Wavef II for CH The signal will be shown on the axe The acquisitioned signal has 256 samples 256 points for larger signals more samples need to be combined The serial interface has a buffer of 512 samples For writing a saved waveform from the computer to the oscilloscope the Write Wavef I and Write Wavef II buttons were used The oscilloscope has two memories and this way it can memorize to signals The signals are saved in a text file signal txt as points This can be used for saving each signal from each channel to the computer make some signal processing and after that send it back to the equipment In the signal txt file also is a signal with 256 samples 256 points Here also a little trick 1s needed to make it work the oscilloscope need to be put in STOR MODE so the REF bit has to be put on 1 logic by software otherwise it will not work This is very important to be done because otherwise if 35 Issue 3 Volume 3 2009 the REF
18. ions vol 44 2001 C Bhunia S Giri S Kar S Haldar P Purkait A low cost PC based virtual oscilloscope Education IEEE Transactions vol 47 2004 pp 295 299 S A Chickamenahalli Hall Interfacing a digital oscilloscope to a personal computer using GPIB Frontiers in Education Conference 1997 27th Annual Conference Teaching and Learning in an Era of Change Proceedings vol 2 1997 MATLAB Creating Graphical User Interfaces MATLAB Instrument Control Toolbox 2 User s Guide HAMEG Instruments Description of Interface Commands Muhammad Sharfi Najib Mohd Shawal Jadin Mohd Razali Dau Development of Real Time Signal Generator Graphical User Interface Using Matlab 6 5 Software Engineering Parallel and Distributed Systems SEPADS 08 7 WSEAS International Conference 2008 pp 103 106 Vladislav Slavov Tasho Tashev Data Acquisition Units Using For Student Labs System Science and Simulation in Engineering 5 WSEAS International Conference 2006 pp 228 231 S M Potirakis M Rangoussi G E Alexakis Exploiting Multimedia for the instruction of Analog Electronics Applied Acoustics and Electro Acoustics undergraduate courses WSEAS International Conference A Etxebarria R Barcena Real Experiments Remotely Controlled Through The World Wide Web Engineering Education EE 08 5th WSEAS IASME International Conference 2008 pp 259 264 A Ascia B Ando
19. mands Its commands are presented in the product datasheet Some commands are quite complicated and need a lot of binary calculation to make them work Some of them are not complete or not well explained and need programming tricks to make them fully functional Some commands are related to other commands These dependencies are explained in another datasheet so to command this equipment a lot of prior study is needed The oscilloscope has a quite old microcontroller and this makes it a little more difficult to program then other equipments Its commands are not standardized the commands are closer to binary code This equipment was chosen because it s not common equipment like the Agilent equipments which quite really simple to program and most of them have drivers for all common communication ports present on an equipment like GPIB RS232 USB or Ethernet 33 PROBLEM FORMULATION The most often used functions needed to be implemented in the computer interface of this HAMEG HM 407 oscilloscope Some functions that are not possible without a computer like saving a graph from the oscilloscope or sending a graph to the oscilloscope were the main target On the computer interface the buttons needed to have similar name as those present on the oscilloscope III PROBLEM SOLUTION A Programming Language Presentation The goal was clear to make a simple but efficient computer interface for the oscilloscope via RS232 in
20. n oscilloscope with complicated SCPI commands with binary calculations With this knowledge now we are capable communicating with almost any equipment It s an old equipment but it still needs to be connected to the computer and it still needed to be programmed As mentioned in the introduction these older equipments are still needed On the other hand somebody needs to make drivers for the instruments for simpler programming This paper s goal is to show how to interpret the SCPI commands and this way to make an instrument driver This paper is just an example how to program more complicated instruments With this knowledge we hope that the communication with instruments will not be a problem REFERENCES N Sulaiman N A Mahmud Designing the PC Based 4 Channel Digital Storage Oscilloscope by using DSP Techniques Research and Development 2007 SCOReD 2007 5 Student Conference 2007 pp 1 7 Tew Yiqi Goi Bok Min Oscilloscope A PC based Real Time Oscilloscope nnovative Technologies in Intelligent Systems and Industrial Applications 2008 CITISIA 2008 IEEE Conference 2008 pp 92 97 R Lincke I Bull A Trutia B Logofatu PC based oscilloscope Semiconductor Conference 1995 CAS 95 Proceedings 7 995 International 1995 pp 229 232 M O Hagler D Mehrl A PC with sound card as an audio waveform generator a two channel digital oscilloscope and a spectrum analyzer Education IEEE Transact
21. s to change the position with only one button so a little trick was needed The program that does the trick is the following INTERNATIONAL JOURNAL OF COMPUTERS AND COMMUNICATIONS function yposl Callback hObject eventdata handles ypl get hObject Value cmdc double Y1POS if ypl gt 15 1 1 15 if ypl lt 15 cypl yp1t 240 end c 160 cypl 13 fwrite handles obj1 cmdc cl fread handles obj1 3 cl As we can see the program is similar but with if statement insertion The whole idea is that the information that we have to send is 16 bits long so we need two decimal numbers The slider is set to the value of 15 and the minimum value to 0 and maximum to 30 The whole screen height 15 40804 the inserted string is the LF 0AA so this way we have FFOAA We split the word in two bytes and get FF and OA we reverse them and get FFh 255d and AOh 160d and these need to be sent in reversed orders With the implemented algorithm we will be able to change the vertical position in brute values changing the MSB In binary the positive values for the second byte are between 000000006 000011115 00h OFh Od 15d and the negative values between 11110000 11111111 FOA FFA 240d 255d the negative values are in the complement of 2 so the lowest value is FFA 255d and the highest is FOA 240d A same program can be made to the channel 2 but using Y2POS w SCPI
22. scope indicates that the equipment is in remote mode and can be commanded just with a computer On the graphical interface the status of the oscilloscope is shown with and edit text indicator where the information ON or OFF is shown depending on the state of the oscilloscope remote or local To return to local mode the Autoset button from the oscilloscope need to be pushed for a few seconds and the oscilloscope will return in local mode The Autoset button s secondary function is returning the oscilloscope in local mode After this operation the oscilloscope will not be commanded eth the PC just with the buttons physically present on the equipment and the remote LED will be turned off To return the oscilloscope in local mode the disconnect button from the computer interface can be used too The Autoset button from the user interface has the same effect as the Autoset button physically present on the oscilloscope it sets the Time DIV and Volt DIV parameters most optimal to the acquisitioned signal For setting the horizontal X POS and vertical Y POS I and Y POS II positions of the signal sliders were used Here a little trick need to be used because for positive vertical position was one command and for negative vertical position was another command but only one slider was used so the two commands needed to be merged in one For setting the timebase TIME DIV and the amplitude VOLTS DIV I and VOLTS DIV also sliders wer
23. terface The software used for programming was MATLAB This software is simple and powerful MATLAB has also a graphical interface which was very useful for our oscilloscope s user interface creation The only inconvenience is that MATLAB has only Windows style controls like sliders buttons check boxes and radio buttons When for example a TIME DIV dial is needed we had to use slider not so suggestive but functional Maybe for a better user interface some National Instrument s software can be more convenient like LabVIEW LabWindows CVI or Measurement Studio for Visual Studio because these software packages have dials LEDs graphs and other controls and indicators which look like the ones on electronic equipments MATLAB has its own advantages too The thing that is very useful in MATLAB graphical interface is that any change on button makes change immediately a change in the MATLAB m code file No need for generate callbacks like in other programming languages like Visual Studio or LabWindows CVI This can be very useful when a complicated code is made B MATLAB Graphical Interface MATLAB graphical interface can be accessed when the guide command is introduced at the command prompter This command will open a window like the one in Fig 2 Here the user can drag and drop buttons sliders and other Windows style controls and indicators needed In the oscilloscope interface sliders Push buttons pop up menus controls
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