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1. b gt Main Panel l0 x Datei Settings Measure Display Help Fenster me eee o E EALCCEREE 0 0E 1 0E 0 2 0E 0 3 0E 0 4 0E 0 5 0E 0 6 0E 0 7 0E 0 8 0E 0 Po fects vc vcr vers vce vcns e r e e l j i i E al a J Jo Curse Cursor 2 Cursor 2 1 f Fig 2 Front panel of the new transient recorder software Below the menu bar is the symbol bar situated containing the most impor tant functions from the menu bar The screen s largest part is acquired for dis playing the signals of each channel The display settings of each channel can be chosen by using the change button on the left side of each channel or via the Display menu in the menu bar At the bottom of the front panel a table for cho sen parameters is situated The control panel of the data acquisition card is shown in Fig 3 All essen tial interfaces and displays can be found in the four index cards Timebase Input Amplifier Trigger and Physical Unit The auto sequence panel is shown in Fig 4 The available functions can be chosen from the corresponding interface and are copied into the auto sequence list The commands listed in there define the current auto sequence which is started by pressing the Auto Record button in the symbol bar The front panel s diagram structure is the code behind the above shown graphical user interface Fig 2 I2. diagram shown in Fig 6 contain an error input and an error output which is con nected to the error input of the following VI Error in and output are in form of a cluster which is comparable to a dataset or a structure in text based program ming languages This cluster contains a boolean a numerical and a string control or indicator If an error occurs the boolean element is set true the numerical element contains the error number and the string the error message The next SubVI which receives the error cluster has then the possibility to decide how to handle the further proceeding Fig 7 shows an example for such an error han dling in the SubVI Clock config If this SubVI receives an error cluster the case Fehler is selected from which the task ID and the error cluster are passed to the following VI Fig 7 right If no error occurs the subdiagram of this case called Kein Fehler is executed If an error occurs during the execution of this case the error cluster is set to error and the error number and the error message AI Clock Config is passed to the error output Fig 7 left The described part of the program containing configuration and routing must only be executed once if the configuration is not changed The next parts of the software which control the start of the data acquisition or the recording of the data can be repeated without re configuring and re routing gt Al Takt Konfiguration AI Clock Config
3. extrai apres l ex perience L avantage de ce system est que vraiment tous emissions acoustiques auraient enregistent A l otre cote on gagne des ensembles de donnees tres grand KEYWORDS Transient recorder acoustic emissions data acquision INTRODUCTION Acoustic emissions are defined as the spontaneous release of localised strain energy in stressed material Due to micro cracking in the material this en ergy release can be recorded by transducers on the material s surface GroBe 2002 Acoustic emission analysis is capable of revealing damage processes in material during the entire load history It is obvious that the recording of damage processes from the microscopic to the macroscopic scale produces a large num ber of events during relative short time spans The number of events can be about several thousands during one test Due to the large number of occurring acoustic emissions within short periods it is obvious that a fast recording system is needed Furthermore the events frequencies are in the ultrasonic frequency range Therefore the transient recorder needs a high sampling rate too The kernel of such a system is the data acquisition part Here a fast and high resolu tion A D converter in form of a measurement card is generally used In the case of that more than one card is used they need to be synchronised The data then 116 Concepts of transient recorder development for acoustic emission analysis is stored by a com
4. vi Diagramm J LAIC i lox Datei Bearbeiten Ausf hren Werkzeuge Durchsuchen Fenster Hilfe Datei Bearbeiten Ausf hren Werkzeuge Durchsuchen Fenster hilfe eek a BRI ol 9 kallot 13pt Anwendungsschriftart IE a n a kallot 13pt Anwendungsschriftart E WkeinFehler h 7 i task ID out which clock 0 no change A dock source no change dock frequency seth alternate clock rate specification no actual clock rate specification error out Fig 7 Error handling within the SubVI Clock config After configuration and start of the recording system the data acquisition cards wait for a trigger condition for data storage All available VIs concerning 125 Otto Graf Journal Vol 14 2003 KURZ WOLTER BAHR MOTZ the idle running time before an event occurs blocked the program i e no precast VI could be used Using a timeout function to stop the data acquisition if no event occurs did not produce satisfying results too Therefore the SubVI Read Data was developed Fig 8 left Data Available por waiting Standard P A Data Available v aster device data 116 FE fave device data Fe fis f iming Settings Blocklength Out Pretrigger Samples Out aster task Dout E a lave task ID out J ve fa ps2 Vv a rror out Fig 8 SubVI Read D
5. Concepts of transient recorder development for acoustic emission analysis CONCEPTS OF TRANSIENT RECORDER DEVELOPMENT FOR ACOUSTIC EMISSION ANALYSIS KONZEPTE DER TRANSIENTENREKORDER ENTWICKLUNG FUR DIE SCHALLEMISSIONSANALYSE DES CONCEPTES DU DEVELOPMENT D UN LECTEUR POUR ANA LYSER DES EMISSIONS ACOUSTIQUES J H Kurz V Wolter G Bahr und M Motz SUMMARY The large number of acoustic emissions occurring during an experiment re quire a fast and high resolution transient recorder system A standard personal computer with a RAID system and two data acquisition cards each has got 4 in put channels 5 MHz sampling rate and 12 bit amplitude resolution build the hardware platform Using this hardware two transient recorder software con cepts were realized The first one is an event controlled system where each event is triggered and stored immediately with a rate of up to 50 events per second The second one is a continuously recording system where the data flow is re corded and stored continuously and the events are extracted afterwards The ad vantage here is that really all events are recorded but really large datasets need to be handled ZUSAMMENFASSUNG Die groe Anzahl w hrend eines Versuches auftretenden Schallemissionen bedarf eines schnellen und hochaufl senden Transientenrekorders Ein Standard PC mit einem RAID System und zwei Messkarten jede mit 4 Kan len 5 MHz Sampling Rate und 12 Bit Amplitudenaufl sung bildet die H
6. RUNGSTECHNIK GMBH 1 AUFLAGE 2002 4 PCI 6110 6111 USER MANUAL NATIONAL INSTRUMENTS EDITION NOVEMBER 2000 2000 130
7. a moving coil instru ment Each control element or display creates automatically a terminal on the diagram surface Fig 1 right Within the diagram functions operators and structures are used which can also be placed by drag and drop operations The diagram s elements are then connected by virtual wires Fig 1 right shows a while loop grey border line and within the loop the two input elements factor 1 and factor 2 and the multiplication operator cross sign The multiplication op erator is connected to the two input elements and the output display product and the stop terminal is connected to the conditional terminal of the while loop After starting the program two number can be multiplied with each other until the STOP button is pressed which cancels the while loop This relative simple example shows the general procedure of programming in G The transient recorder software is a much more complex problem but it is in principal the same basic system The software s front panel Fig 2 has got a menu bar including the menus File Settings Measure Display and Help The menu Settings contains dialogs for the data acquisition settings and for the definition of the auto sequence The menu Measure is for starting and stop ping the measurement as well as the auto sequence The menu Display contains the possible display settings and the Help menu calls the help functions 119 Otto Graf Journal Vol 14 2003 KURZ WOLTER BAHR MOTZ
8. annels The reason is not completely clear If it is a software error the problem may be searched within the National Instruments software NI DAQ i e within the C libraries The problem might also be based within the buffer organisation and monitoring routine It is also possible that the data flow is around the limit of what the system bus of a standard personal computer is able to pass to the hard disk i e the problem is a hardware problem The disc space of 120 GB makes recording times of more than 30 minutes possible but the user has to take into consideration that for the acoustic emission extraction further disc space is needed The extraction is performed by a thresh olding algorithm The event extraction works automatically but however it is relatively slow Therefore removable hard discs are used in the transient re corder so the data analysis can be realised on another computer A further pos sibility would be to divide the raw data file containing the continuous data into several pieces and apply the extraction procedure on them Until now there is not much experience in handling the huge data sets gained with the continuous recording system The event controlled recording system is not able to record all acoustic emissions occurring during one experiment But is has got a much better per formance than the until now used event controlled system which was only able to record 1 event per second with 5 MHz sampling rate amplitud
9. ardware Plattform Auf Basis dieses Equipments wurden zwei Transientenrekorder Systeme umge setzt Das eine System zeichnet kontinuierlich den Datenfluss auf aus dem hin terher die einzelnen Schallemissionsereignisse extrahiert werden Der Vorteil dieses Prinzips ist dass wirklich alle Schallemissionen erfasst werden Aller 115 Otto Graf Journal Vol 14 2003 KURZ WOLTER BAHR MOTZ dings m ssen hier teilweise sehr grohe Datens tze bearbeitet werden Das ande re System arbeitet Ereignis basiert d h wird ein Ereignis durch die Triggerbe dingung als solches erkannt so wird es sofort abgespeichert Mit diesem System wird dabei eine Speicherrate von 50 Schallemissionen pro Sekunde erzielt RESUME Le grand numero des emissions acoustiques qui se manifestent pendant une experience a besoin d un lecteur pour des emissions acoustiques qui est vite et qui est en haute definition Un ordinateur normal avec un system RAID et deux cartes de mesure chaque avec 4 canals 5 MHz quote part de balayer et 12 bit resolution des amplitudes forment la base de hardware Deux systemes diffe rentes pour enregistrer des emissions acoustiques etait realiser a la base de ce hardware La premiere systeme enregistre chaque emission acoustique juste apres le determination Avec ce system un quote part de accumulation de 50 emissions acoustiques par seconde aura gagne La deuxieme systeme enregistre les carateristiques continu et chaque emission acoustique aura
10. ata left and Subdiagram Waiting right which corresponds to the Subdiagram Data Available on the left side for idle running time handling The SubVi Read Data Fig 8 left imports zero datapoints from the master device in a while loop by using the Sub VI AI Read i e the loop cannot be blocked The parameter Scan Backlog which is returned by this VI says how many datapoints are staying in the buffer after the SubVI s execution As long as no trigger condition is fulfilled the Scan Backlog value is zero and the subdiagramm Waiting Fig 8 right of the following case structure is passing only the master and slave IDs and the error cluster to the following loop execu tion where again Scan Backlog is read out The break switch within the subdi agramm which can be used via the VI server function by other VIs enables to stop the data acquisition if the corresponding control button is used on the main panel If the trigger condition is fulfilled and all data is in the buffer the Scan Backlog value is the value of the blocklength Then the subdiagram Data Available is executed where the data readout of the master and the slave device from the buffer is realised Activating the termination condition of the while loop within this subdiagramm the SubVI Read Data is ceased The data is now available in the terminals master device data and slave device data for storage or display 126 C
11. ceives data The Notifier s data output is connected to the input tube of a for loop whose auto indexing is activated The tube s output is connected to the selector of a case structure which is situated in the for loop The auto indexing affects that the elements of an array which is connected to the input tube of the for loop are passed one after the other to the loop The loop counter n terminal which normally controls the number of loop executions does not need to be connected to the loop The loop is executed with respect to the dimension of the array The mode of operation works as follows If the user initiates an event an array con sisting of symbolic constants is situated at the input tube of the for loop During each execution of the for loop one symbolic constant of the array is read i e During the firts loop execution the Config and Route constant which is passed to the selector of the case structure that executes the corresponding Config and 122 Concepts of transient recorder development for acoustic emission analysis Route subdiagram Fig 5 lower loop Having read all constants the Notifier lapses into a sleeping mode until a new event is initiated Other events create ar rays consisting of different symbolic constants which call certain case structures Such a programming architecture is called state machine The data transfer of subdiagrams of the state machine is realised by so called shift regist
12. data acquisition card Within the post trigger mode or if the pre trigger samples are set to zero this internal signal is the starting point for the data acquisition During the pre trigger mode the internal signal stops the acqui sition because the data acquisition has already started and the pre trigger sam ples must be seized before the trigger condition is fulfilled Each data acquisition card has got a 20 MHz time base from where the needed timing signals are send e g to the A D converter The board clock can also be routed by the RTSI bus though other data acquisition cards can use the same time base This is performed by the second call of the SubVI Route sig nal where the signal Board clock is send to the RTSI bus Fig 6 The next two SubVIs configure the slave device in the same manner as described for the master device Configuring the trigger of the slave device is different from the master device trigger configuration Herefore a digital trigger is used and the trigger channel is not an analog external signal but the RTSI 0 connection which uses the master device trigger signal Though the both cards are triggered si 124 Concepts of transient recorder development for acoustic emission analysis multaneously Finally the board clock of the slave device is set to the RTSI clock that the sampling is synchronised in phase and frequency A further important point is the error trapping Most of the SubVIs of the
13. e This leads to a sequential data flow which is useful here The left side of Fig 6 contains the controls Master device and Slave de vice which represent the two data acquisition cards The decision which trigger channel is chosen in the control panel determines which card will be master and which slave The parameters Master device Master channel scan list list of channels used for measurement coupling amp input config input configuration and input coupling and Blocklength are set in the control panel and passed to the SubVI AI Config which is executed first The sampling rate is set in the 123 Otto Graf Journal Vol 14 2003 KURZ WOLTER BAHR MOTZ SubVI Clock config Trigger channel trigger slope trigger level and hystere sis are set in the SubVI Trigger config Lene a EI ane ae ma tem a a E Error ou pa N EE EER PE a on a ae tl RTsi0 boo Fig 6 SubVI Config amp Route for configuration and routing The trigger procedure is very important for the whole process of data ac quisition Therefore a more detailed description will be given If the trigger condition is fulfilled the analog trigger on the data acquisition card generates an internal trigger signal This internal digital trigger signal is send by the SubVI Route signal to the RTSI bus connection RTSI 0 where it can be received by the second
14. e resolution 12 bit A performance test revealed that the new transient recorder system is able to trigger and store about 50 events per second with a sampling rate of 2 5 MHz and 12 bit amplitude resolution This transient recorder system produces large data sets too but much less disc space is needed than with the continuously re cording system The larger data sets enable a better analysis e g an automatic onset detection algorithm with a rate of success of about 40 leads generally to 129 Otto Graf Journal Vol 14 2003 KURZ WOLTER BAHR MOTZ more significant results with 3000 recorded events than having only recorded 300 Concerning the system s hardware performance better data acquisition cards are available 16 bit amplitude resolution 12 channels 10 MHz sampling rate 6 GB onboard memory but the price of one of the best systems available now is factor 10 higher than of the one we developed ACKNOWLEDGEMENTS These investigations are part of our work in the collaborative research cen ter SFB 381 at the University of Stuttgart which is financially supported by the Deutsche Forschungsgemeinschaft DFG We gratefully acknowledge this sup port REFERENCES 1 GRossE C U BASICS OF ACOUSTIC EMISSION MEASUREMENT TECH NIQUES KLUWER ACADEMIC PUBLISHERS HINGHAM MA USA CH 9 P 45 2002 2 LABVIEW BENUTZERHANDBUCH NATIONAL INSTRUMENTS EDITION JANUAR 2002 2002 3 OBJECTVIEW BENUTZERHANDBUCH VOGEL AUTOMATISIE
15. ers A shift register is a pair of connections which are situated on the vertical sides of the loop frame triangle signs in the lower loop of Fig 5 The connection on the right hand side triangle upwards stores the data at the end of one loop execution that it can be used in the next run as input by the other connection triangle downwards A shift register can be used with differ ent data types The advantage of such an architecture is the simple way of ex tending the program If further functions are needed the corresponding case structures are implemented in the state machine and if needed also in the event control Until now the used programming environment LabVIEW was introduced and the main features of the graphical user interface of the transient recorder software were shown In the following a few important details of the coding are presented Using 8 sensors two data acquisition cards are needed Herefore the syn chronisation of the cards is important Each card can be used separately for sig nal recording with up to 4 sensors But for an acoustic emission analysis it is important that the cards have got the same timebase i e they need to be syn chronised Therefore the SubVI Config amp Route was developed Fig 6 Further SubVIs are implemented in this routine and connected by the Daisy Chain Procedure Object VIEW 2002 That means the output parameters of one VI represent the input parameters for another on
16. file Kanalprofil Neu Profil2 L schen Umbenennen Einstellen OK 0 0244 Y Fig 10 Screenshot of DevTRec The data visualisation is performed using the above shown conversion for mula Using the menu bar it is possible to decide how many values are shown and how many values per redrawing will be shown That means it is possible to view even huge signal in a kind of film PERFORMANCE OF THE DEVELOPED SOFTWARE AND CON CEPTS FOR THE DATA ANALYSIS The two described transient recorder systems on one hardware platform were developed to be able to store as much events per second as possible The 128 Concepts of transient recorder development for acoustic emission analysis continuous recording system records all occurring acoustic emissions But they need to be extracted from the continuous data stream That means the user has to deal with large data sets The point of concern using this system is not the stor ing rate but the effective handling of the data Each data acquisition card is able to use a sampling rate of 5 MHz If the two cards are used coupled and synchronised the sampling rate for the event controlled system is reduced to 2 5 MHz The reason herefore seems to be that the onboard FIFO First In First Out memory which has got a capacity of 8 kB is not able to pass the data fast enough via the PCI bus However the continu ously recording system is only able to sample with 2 MHz using all 8 ch
17. igger mode one input channel or an external signal is the trigger source The trigger level has got a resolution of 8 bit Within the digital trigger mode an external TTL signal is used Furthermore triggering by a software signal is also possible and pre and posttrigger are supplied too A flexible interface which can be used for generating a timing signal is also implemented on the measuring card This interface can be used for routing the timing signal to other data acquisition systems or to an external output The routing possibility is essential for a transient recorder system with two or more cards because there is a need of sending the clock pulse as well as the trigger pulse from the trigger channel to the other measurement cards This is realised via the RTSI Real Time System Integration bus which is a simple connection between the data acquisition cards PCI 6110 6111 2000 The up to now short description of the chosen hardware will be completed by a brief description of the two software systems in the following which control the whole recording implemented on the data acquisition unit The first one is an event controlled program while the second one is a continuous recording system DEVELOPMENT OF AN EVENT CONTROLLED TRANSIENT RE CORDER SOFTWARE The event controlled transient recorder software was developed with Lab VIEW 6 1 using the Programming language G which is widespread in the field of data acquisition and measurement sy
18. oncepts of transient recorder development for acoustic emission analysis DEVELOPMENT OF A CONTINUOUSLY RECORDING TRANSIENT RECORDER SOFTWARE The continuously recording transient recorder system is based on the same hardware platform as the event controlled one The software DevTRec is written in Visual C The data acquisition cards are approached by the C libraries of National Instruments NI DAQ Lab VIEW 2002 The data acquisition is organised via a ringbuffer which enables measurements with up to 8 channels and 2 megasamples continuously Fig 9 Takt ber RTSI Bus Master Festplatten Fig 9 Ring buffer organisation Though the experiment is recorded completely The data analysis is per formed afterwards Due to the buffer arrangement the data is organised block by block in a binary file and needs to be sorted afterwards Therefore the optimal performance is guaranteed for data acquisition The data acquisition cards write the data block by block into the ringbuffer That means at first card number 1 writes a block of data into the ringbuffer then card number 2 then number 1 again and so on Within each block the data of each channel is lined up in succession Due to the knowledge of the blocklength it is then possible to put the data in the correct order This ordered data is written to the so called Basefile The data is still in a binary 12 bit format The format conversion uses the following formula measu
19. puter system which must be fast during the process of data storage and which must have sufficient disk space All these processes are con trolled by the corresponding software The rate of acoustic emissions during experiments especially in concrete can be about 30 or more events per second Commercial data acquisition sys tems including the software detect between 2 and more than 100 events per sec ond depending on the time delay of the system during the process of storage The sampling rate for concrete specimens should be greater than 1 MHz with a high amplitude resolution The required disk space should be about several gigabyte The more sensors are used the better the data analysis works There fore in general more than one data acquisition card is needed The cards then need to be synchronised These are the benchmarks a good system for acoustic emission analysis on concrete should achieve REALISATION OF THE REQUIRED HARDWARE STANDARDS The most limiting factor concerning the chosen hardware and not men tioned yet is the constricted budget With an infinite budget it would be possible to go far beyond the required hardware standards But with the chosen concept a relatively cheap solution was found which fulfils all mentioned benchmarks The chosen hardware is a standard personal computer with an AMD Athlon 1800 processor and a raid controller onboard The system has got 1 GB RAM and 3 hard disks each with about 60 GB memory The fi
20. red value 10 2048 gain real value 127 Otto Graf Journal Vol 14 2003 KURZ WOLTER BAHR MOTZ Finally each event is extracted from the continuous data file Herefore a simple trigger level can be chosen which defines the occurring of an event Fig 10 The measured values are compared in succession to the trigger level value It is possible to decide if a definite number of samples is extracted after the trig ger level is reached or if the extraction of the event is finished if the values sink again below the trigger level The events are written separately to a file whereas an information file is also created for every event which contains the relative trigger time Due to the fact that the Basefile is not erased the extraction can be repeated with different trigger values leixJ I tinstellung Kan le instelungen Ausf hren F Messkarten Messkarte 1 Karte hinzufiigen 810 12 14 16 18 20 22 24 26 28 30 32 3 ata rhen p Kanaleinstellungen gew nschte m gliche WVerst rkungsfaktor 2 0 h Abtastrate Heats 1250000 1250000 o Signal triggem bei 1000 my Anzahl Signale vor Messvig nach Messvrg Messbereich 5 bis 5 Y 100 sd Kanal hinzuf gen i Kanal l schen oK Abbrechen a jailwa la jata Jaia ia jula Japa jaja for fa fa a Ta i Ce T R a e ae ee ee ee mec j Bld Ma ti N if ri H F 0 000034s i ji Kanalprofil Manager B F p Pro
21. rst hard disk contains the operating system while the two other hard disks are the memory for the tran sient recorder They are configured as a RAID 0 RAID means Redundand Ar rays of Inexpensive Disks That means a compound of hard disks which com plement each other RAID 0 especially also called striping arranges the data equally on both disks The data transfer rate is so twice as high as with one disk With respect to fast data processing on a second system the two RAID disks were set into two carrier bodies Data acquisition is realised with two measurement cards of type PCI 6110 from National Instruments implemented in the personal computer The connec tion between sensors and data acquisition system is realised via a self designed panel Each measurement card contains 4 analog inputs 2 analog outputs and 8 digital in outputs as well as two 24 bit counter timer Concerning the transient recorder only the analog inputs are needed Each analog input has got an own ADC with a resolution of 12 bit differential input mode input coupling 117 Otto Graf Journal Vol 14 2003 KURZ WOLTER BAHR MOTZ switchable between DC AC and 8 bipolar ranges from 0 2 V to 42 V The sampling rate can be chosen between kS s and 5 MS s The onboard trigger is a bit limited It is only possible to trigger on one channel and logical connections between different channels are not possible A slewrate trigger is not realised too Using the analog tr
22. stems LabVIEW 2002 Using Lab VIEW the coding is realised in a graphical way which is different to e g Fortran or C but easy to learn Furthermore the program flow in LabVIEW is not se quential but related to the data flow This simplificates process parallelization Other programming features like loops and sequences are also available as well as subroutines called SubVI VI virtual instrument Each LabVIEW program is called a VI and consists of a front panel and a diagram In the following a simle example shell demonstrate the programming procedures within LabVIEW Fig 1 118 Concepts of transient recorder development for acoustic emission analysis I Multiplikation1 i Datei Bearbeiten Ausf hren Werkzeuge Durchsuchen Fenster Hilfe Datei Bearbeiten Ausf hren Werkzeuge Durchsuchen Fenster Hilfe een Eeln e ke ot Produkt 5 0 75100 15 0 2 5 0 0 Drehspulinstrument Fig 1 Example for the structure of a LabVIEW program left front panel right diagram Two numbers shell be entered on a user interface then multiplied with each other and finally the result displayed on a moving coil instrument Fig 1 left Pressing the stop button the program is terminated The buttons instruments and controls can be placed on the front panel which is the user interface by drag and drop operations The example shows two controls factor 1 and 2 a boolean control button STOP and a numerical display in form of
23. t Anwendungsschriftart ix a E amp 1 P __ Array erstellen eStart and Read Data 7 i E Display Data v FALSE vP a 7 First Notifier 3 Record Wert ge ndert Ba st Notri BI g 2 Eann Melder anfordern Simple Error Handler vi Config and Route arian m aD 4 X 20 Meldung senden IFOR Schleife Channel Settings Trigger Settings Timing Settings Auto Sequenz master device data slave device data Master task ID Slave task ID Error No of Channels Card i max 4 Fig 5 Diagram of the front panel showing 2 parallel while loops Fig 5 shows the event case which will be executed if the record button on the front panel Fig 2 is pressed Then an array consisting of symbolic con stants with the elements Config and Route Start and Read Data Unroute and Display Data will be created This array leaves the events structure using a so called tube with destination to the First Notifier lower loop in Fig 5 A Notifier enables the communication between 2 independent parts of a block diagram Its principal is comparable to a mailbox which also sends and re
24. ts architecture will be shown in the following The VI Main Panel is the top level VI Fig 5 It consists of 2 while loops 120 Concepts of transient recorder development for acoustic emission analysis which are executed parallel The upper loop shows the event control The user activates an event e g by pressing a button on the front panel or choosing a menu entry from the menu bar The programmer defines which control elements are activated by a certain event using the so called event structure inner frame in the upper loop of Fig 5 Each event has got an own case in the event struc ture whose subdiagram will executed if the corresponding event occurs As long as no event appears the event structure is in a sleeping mode which saves proc essor capacity f E gt Control Panel Differential 20 000 20 000 ooz coo2 Differential 20 20 120 000 20 000 coo3 Differential 20 20V_ 20 000 20 coo Differential 20 20V 20 000 20 coos Differential 88 8 88 coo6 Differential 20 000 20 coo Differential 20 000 20 coos Differential 20 000 20 818 Minin Auto Sequence Record Record Save Restart Fig 4 Auto sequence panel 121 Otto Graf Journal Vol 14 2003 KURZ WOLTER BAHR MOTZ Main Panel Main Panel6 vi Diagramm a laj xj Datei Bearbeiten Ausf hren Werkzeuge Durchsuchen Fenster Hilfe Schlie en ela n E bea of 13p
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