User Interface Development for an Autosampler, Based in LabVIEW
Contents
1. we can see a New button By clicking this button a newer dialog panel will be shown see Figure 4 At this point we can define measures along X and Y directions in millimetres which correspond to the length and wide dimensions of the pipes support board and the number of pipes existent in each direction Finally by clicking the save button a newer dialog box as the one in figure 5 will be shown and their we can give to the just defined tray parameters a name in order to save it in a file this will allow to use these same tray definitions later Autosampler pt P Define tray Creat New Open Existing Sequency Actual Position aut z i mm Mode pastori a Intermediary faoo Y Size mm Y Position Position fis Pipe 5 Z Position x Position 0 o 25 Retraction i Time s Positi 50 AN soi 5 100 Y 1 Pipe X Array Array of position to cover than EEEE EEEE EnG eek ooo Y Array 2 m2 Re RE 2k eee Ek 2 ekeek ek kk 2 90 o fo 2 Array 50 50 50 50 150 150 50 so so lso iso 50 150 50 so fso 50 so 5o 5o so solo fo wo Time Array FC a a a Ca a a eC en en on Figure 3 graphical interface for an Autosampler X Size mm X Pipes Po Size mm Pipes To EEr Figure 4 The New panel Guardar como Procurar em user lib E 200_200 E otabuleiro uni_pos EG E abrir E Read_comi ffe Untitled Os meus E actualiza _passos E2. serial RWR E Untitled documentos re qt Center _Index E tab0_0 E versaog E E Center_Index2 tab2 ea Write_Cycle conf comi Gi tab2_experiment Ambiente a E conyv_mm_to_p fe tab50_50 dir mnu E tab100_60 Gravar E tab100_100 E manual E tab200_100 m ae GB manual_z E tab200_200 saj Mi ee new E tab220_110 9 E new E tab300_120 E new txt bak E tab320_210 computador E order_Index E tab400_300 Os meus locais Nome do ficheiro X na rede Ficheiros do tipo All Files v Cancelar Figure 5 The Save panel and its VI Grava For saving definitions in files we have developed a VI named Grava where all inputs are converted to string format for easy processing in file As we can see in Grava VIs we don t have input or output connections 3 3 2 The Open function Just under the New button of the interface we can find the Open button When clicked this button will open a newer dialog box similar to the one in figure 5 where we can chose a tray already defined that the human operator wants to use Once the user has chosen the file containing the desired data the program will read a string that contains tray s parameters and will convert them in an array of 32 bits values only in this format LabVIEW functions will be able to use them As we can see in VI Abrir it only has a single output which is the array conta
3. User Interface Development for an Autosampler Based in LabVIEW Programming Language Fabrice Gon alves Luis Santos Rui Santos Pedro Faia ICEMS Coimbra DEEC FCT Universidade de Coimbra P lo 2 3030 290 Portugal 2 DEEC FCT Universidade de Coimbra P lo 2 3030 290 Portugal Autosamplers are devices with the capability to collect and deploy samples for further analysis in pipes uniformly distributed within predefined trays with remarkable speed and accuracy Such devices are widely available in the market and whilst their prices are high it s programming and tasks are apparently simple Taking this economic problematic and adding the portability concept thus came the idea for the present work an Autosampler operating over 3 axis X Y and Z capable of executing the same operating tasks of the Autosamplers already available in the market configured and controlled by means of a user friendly application In this paper we will focus the development of a user friendly application that runs on a Personal Computer PC developed using LabVIEW programming language that incorporates several functionalities that simplify the use of our Autosampler The specific Autosampler for which this application was developed is fully described in another paper Keywords LabVIEW Motorised System Autosampler 1 Introduction We can actually find in the market a large number of multi axis positioning systems also re
4. can be made easily the creation of new VIs or simply the modification of a one already existing is very easy to achieve As stated all VIs can and will be saved in a library allowing their utilization by other applications strX n r Figure l Message formats that compose the implemented communication interface standard data message format READY message format and OK message format 3 2 Communication Protocol Before starting the description of the developed toolboxes for our interface we had to create a sort of communication protocol using RS232 so that our interface can send to the microcontroller the number of steps to execute movements along X Y Z The communication protocol is based in a Master Slave architecture that uses a Fieldbus type topology It is supported by the physical protocol RS232 and composed by a group of messages whose format can be seen in figure 1 In the implemented protocol the messages are traded between the PC interface and the microcontroller as follows 1 the resident interface running in the PC from know on only referred as PC must be initiated first as it must wait for an OK message from the microprocessor As soon as the OK message is received the messages trade can actually start 2 a READY message is sent by the microprocessor to the PC indicating its availability to receive positioning data 3 the PC then computes the necessary data using a pro
5. cedure which is described in another paper and sends it in form of strings sequentially to the microcontroller using the standard data message format of figure 1 In this message four strings are sent to the microprocessor the first three correspond each one of them to the desired X Y and Z positions in steps and the fourth one concerns the time the Z axis is supposed to be in lower position before retracting this time can be user defined being 1 second the default value 4 meanwhile the microcontroller is waiting to read this message from the serial buffer it must be emphasized that each one of the strings is terminated by a n r sequence Only after receiving the full message the microcontroller will process data and act on the motors 5 as soon as the motors have completed their task a READY string will be sent to the PC 6 subsequent position movements of the Autosampler are achieved repeating steps 2 through 5 a Figure 2 Control VIs for RS 232 Conf COMI To achieve the communication we have developed three VIs one for RS 232 configuration another for RS 232 reading and finally a last one for RS 232 writing Those are represented in Figure 2 3 3 Software functionalities In order to control our Autosampler we have developed the interface shown in Figure 3 The functionalities there present are described below 3 3 1 The New function On the top left corner of our interface in Figure 3
6. es them that opportunity that is it allows the operator to insert a new position with different depth along Z direction and different retraction time This way when clicking the Pause button in the top the right corner of the front panel interface the sequence will be stopped highlighting the Pause button Then simply by clicking the Insert button a new window panel will appear as the one in figure 10 where a new position can be defined similarly as in Manual Mode previously described By clicking the Run button the system will execute this newer intermediate position stopping after it The user can define for the stopped sequence the number of intermediate positions he wants To go back and continue to execute the previous stopped sequence of positioning movements users will have to deselect the pause mode just by clicking the Pause button 4 Conclusions and future work As we have seen the developed software interface has entirely fulfilled all initial specifications originated by our main objective the design and development of a portable and easy to use Autosampler system In fact the software interface is extremely straight forward to use with a learning time of about 10 minutes within this time any Human operator will learn the basic aspect of its functionalities This interface can be adapted to other than the here presented Autosampler control In this case a wider range of funct
7. ferred as XY or XYZ tables depending on the number of modules used There exist a large number of possible applications for this kind of devices such as microscopy equipments CNC devices or Autosamplers where the speed accuracy and high load capacity are very important Referring to an Autosampler we can say that it is an automatic 3 axis positioning system that can be not only used for sample preparation but also with analytical technologies volatile organic impurities measurements or alcohol rate in blood detection even in toxicity analysis or with chromatography and atomic adsorption systems Autosamplers are designed to optimize robustness and to avoid mechanical erosion since those are the major generators of system faults due to laboratorial environment and repetitiveness of systematic sample processing To command an Autosampler an onboard console can be incorporated or it can be controlled using a Personal Computer PC interface 2 Autosampler description Autosamplers use in general assay pipes where samples can be deployed treated mixed or even collected for further analysis To support those pipes it is usual to make use of rectangular trays with variable sizes and configurations where pipes are placed Instead graphite recipients that support high temperatures as the ones needed for atomic adsorption systems can also be used We can describe an Autosampler sequence starting by defining the kind
8. ining the tray s parameters Figure 6 The VI Abrir Those values will be displayed in the interface frontal panel just beside the New and Open button to inform the user about the tray he is using 3 3 3 Defining sequence Once the user has chosen the tray he wants to use he can now select the pipes from which he wants to collect or depose samples This can be done graphically or manually choosing the Graphic or Manual mode in front panel 3 3 3 1 Graphic Mode If the Graphic button is clicked then a new dialog window will appear This new window is as the one shown in Figure 7 4 4 4 4 4 4 4 4 4 4 4 4 Jd 4 L weevwvvevevvvvvvwvw VVV wewevwevwevevvevvvvv VVV weewevwevevevevwvvvvvvw wv wewevwevwvevwvevevevvevvwvw wewevwvwevwvvwvvevwvvevvwvw we weuwevwvwvevwvevvvvvvv wv wewevwevwevwvevwvevwvevwvevwvvvwvww wf wewevwevwevwvevwvevwvevwvevevwvvwvw wf wreuwevwevwvvevvwvevwvwvvwvwvw wv wewevwvwevwvvvevvvvw vw wewevwevwvevwvevwvevevvevvv wv wewevwevwvevwvevwvevvwvevevvwvw wv o fo Jo fo fo fo fo fo fo fo fo fo fo Jo fo fo fo fo fo fo fo fo fo fo fo 0 fo fo fo fo fo fo fo Jo fo fo fo Jo fo fo fo fo fo fo fo Jo fo fo fo fo Figure 7 The Graphic Mode In figure 7 we can see the dialog window for tray representation for the moment a tray with a maximum size of 20 pipes along X direction and of 15 pipes along Y direction can be used User
9. ions should desirable be implemented such as substance data base or a substance analysis tool this last one would produce data reports Such human control interface upgrade should also be accompanied by the necessary mechanical system transformations adequate to the intended system usage Future work will include the development of newer functionalities which will give the users the possibility to obtain a maximum profit of their equipment For instance a To give the possibility to define the type of sample This means that for different samples we have different retraction times due to viscosity of the liquid and so one With this functionality the user can previously define what kind of material the system is going to inspect and this way define for the complete tray the retraction time and depth or do it individually for each pipe position b Save in a file the kind of sample defined by tray or pipe for posterior use c During system pause permit the insertion of an entire newer sequence and give the chance to repeat it a certain number of times Acknowledgments Paralab S A for the technical and financial support References 1 S Kock W Schumacher A parallel X Y manipulator with actuation redundancy for high speed and active stiffness applications IEEE International Conference on Robotics and Automation pp 2295 2300 Louvain 1988 2 K A Jensen C P Luska L L Howell An XYZ micromani
10. nual Mode At this time pipes position pipes depth and retraction times will be chosen using the X Position Y Position Z Position and the Retraction Time s controls respectively To save a position the users will have to click in the Next button To modify an already saved position users will have to click in the Previous button Like in Graphic Mode 25 positions can be saved and viewed in X Y and Z array on the bottom off the interface front panel s To start the sequence the user just has to click the Run button Figure 9 Real time visualization panel 3 3 4 Real time sequence display Once a sequence is running a new panel will appear showing in real time the pipe position where the Autosampler is actually on the pipes support board This panel is represented in Figure 9 In this figure we can see a tray of 12 by 9 pipes where the Autosampler is actually in position 6 5 Posi o Z Posi o X 0 A 2 Tempo de T Jo 25 j Recolha s 4 Posi o t J J i 0 1 a tubos x 1 Indice maximo de X Indice maximo de Figure 10 Insert panel 3 3 5 Intermediary Position When discussing with several end users Autosampler interface features some of them referred the necessity of interrupting a sequence in order to insert a new position in the running sequence To respond their request we have implemented a Pause function which giv
11. of tray that is going to be used as support first step This one can be saved in a file of trays for further use second step The next step will be to define the sequence of pipes that the Autosampler will have to cover as well as the retraction time and depth that Autosampler must use for the movements along the Z direction third step At this moment the mechanical system can actually start its displacement to the first position firstly by moving along X axis then along Y axis and finally along Z axis to drop or extract the substance existing in the pipe Once retraction time as terminated the Z axis will be moved once again retracting to its initial position The latest described procedure will be repeated for all pipes previously defined in the third step Once all the programmed movements have been executed and the sequence is completed the mechanism returns to what we call reference position moving again firstly along X axis and then along Y In this paper we will describe the development of a user friendly software interface for a PC used to control our Autosampler it has a modular design which will allow future upgrades of the interface and simultaneously maximizes the usage that can be given to this kind of mechanisms even by a non specialist human operator In order to implement this interface LabVIEW development tool was used It is a tool that permits in first place graphical programming supplying many gra
12. oid microcontroller of such computation due to time processing limitations 3 Graphical User Interface 3 1 What s LabVIEW LabVIEW Laboratory Virtual Instrument Engineering Workbench is a software development tool based in graphic s programming G language similar to other programming languages like C C or BASIC The most important difference is that LabVIEW uses graphic s programming by means of block diagrams in opposition to text programming style supported by the referred programming languages LabVIEW like C or BASIC is a programming language of general use with a wide range of function libraries for several programming task LabVIEW includes libraries for data acquisition data analysis and data presentation for data storage and for instrumentation control It s fully tailored for diverse hardware communication whether RS 232 or RS 485 are used either other type of data acquisition boards are employed Program modules or full programs in LabVIEW are known as virtual instruments VIs due to their appearance and working operation principles However VIs functionalities are similar to conventional text programming language functions A VI consists of an interactive interface with the user and of a flux data diagram that works like a source code with icons and connections permitting that a VI is used by upper level VIs Specifically VIs reunite the following functionalities User interacti
13. phic devices like push buttons thermometers manometers etc supporting at the same time the physical protocol RS232 and secondly it allows the utilization of files and much more The software interface developed comprises the following features that will further discussed defining a tray of pipes by is lengths in millimetres and by how many tubes it is compose in X and Y direction saving this tray in a file for further use opening a tray that is already defined in a file selecting the sequence path of our sampling system graphic or manually selecting different retraction times for each pipe selecting different depths in Z direction for each pipe showing the covered path by the system over the tubes to test in real time making a pause in a sequence already in curse and give user the possibility to insert a new position to sample with depth and retraction time functionality The actuation of linear modules is made by the use of three step motors controlled by microstepping technique based on signal modulation using Pulse Width Modulation Motors control is achieved by a microcontroller from MICROCHIP family which has servo function and is totally autonomous This one receives positioning commands in the form of step numbers for each motor sent by the upper level interface located in the PC and executes them The conversion of millimetres to steps is performed in the interface in order to av
14. pulator with three translational degrees of freedom Robotica vol 24 3 pp 305 314 2006 3 Foundation fieldbus provides automation infrastructure for operational excellence ARC White Paper ARC Advisory Group 2007 4 P Emerald R Peppiette A Seliverstov Monolithic Programmable Full Bridge Motor Driver Integrated PWM Current Control And Mixed Mode Microstepping Allegro Microsystems 1997 5 Michael Predko Programming and customizing PICmicro microcontrollers McGraw Hill 2 Edition 2002 6 National Instruments LabVIEW User Manual National Instruments Corporation January 1998 Author s address Departamento de Engenharia Electrot cnica e de Computadores Faculdade de Ci ncias e Tecnologia da Universidade de Coimbra Polo 2 3030 290 Coimbra Portugal
15. s can now choose pipes where samples are going to be collected or deposed simply by clicking over the pipes position imagined in the same way for the naval battle game For each selected tube users are given the possibility to define different depth displacement along Z direction using the Z Position bar and different retraction times in seconds by means of the Retraction time control button Once users click in one position after have chosen the corresponding depth and retraction time it will be lighted on confirming that the command is accepted i e that that position configuration has been added to the movement sequence immediately after position will be lighted off If by mistake users define a non wanted position for the sequence it can be modified by clicking the Previous button When all positions for a maximum of 25 are defined users can confirm them looking to X Y and Z array on the bottom of panel If everything is correct pushing the Run button will start the movement along the just defined sequence 3 3 3 2 Manual Mode If the Manual button is clicked then users will have to define the sequence of pipes position by acting in the control buttons of the frontal panel shown in detail in Figure 8 ll J 6 Run 4 a prm d o0o PEEEEEPP PP PPEEEERER ERE PEPE 0 fo fo Jo fo fo fo fo fo fo fo fo fo fo fo fo fo fo fo fo fo fo Jo fo fo Figure 8 The Ma
16. ve interface known as Frontal Panel due to its resemblance with a physical instrument front panel Normally it s constituted by buttons graphics and other controllers and indicators This allows data entrance with mouse ore keyboard and screen output VI receive instructions they receive data from a block diagram G language based Block diagrams simplify errors and program problems detection turning them easily identifiable Block diagrams are the source code of the VIs VIs are hierarchical and modular they can be used as main programs or simply like sub functions One VI inside another is called a sub VI The icon VI and connections works like a parameters graphic list so other VIs can pass data to sub VIs In this way we can say that LabVIEW programming mechanism is a modular mode one allowing an application to be divided in many simpler tasks This modularity also allows the use of previously developed sub tasks as functions for other programs too let s say it can work as a library for other software packages So the first step will be the implementation of newer VIs for each sub task witch afterwards will be used in newer block diagrams that execute more complex tasks In the last step the final application level will be the one that contains all sub VIs grouped in such a way that all desired features of the user interface are implemented As VIs can run separately beside error detection changes
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