Certified LabVIEW Developer Exam Preparation Course

Transcription

1 NI Training & Certification Certified LabVIEW Developer Exam Preparation Course Jason Strydom Application Engineer National Instruments

2 Agenda CLD exam process, format and scoring CLD exam objective and theme Design your way to exam success Preparation resources and exam tips Questions 2

3 CLD Exam Logistics CLD Exam Process CLD Exam Grading 3

4 CLD Exam Process A PC with LabVIEW 2013 is provided Application development specification includes the following: Screen shot of Front Panel and the VI on USB Key Description of the controls and indicators General requirements Functional specifications of the application LabVIEW documentation, Express VIs and examples may be used No external resources permitted Time allowed for exam: 4 hours 4

5 CLD Exam Grading Criteria Grading Criteria Points on Exam Percentage Functionality % Style % Documentation 10 25% Total Points % Passing grade is 70 % or higher 5

6 CLD Exam: Objectives and Themes CLD Exam Objectives CLD Exam Themes 6

7 What skills does a CLD demonstrate? Problem solving skills LabVIEW competency Modular, scalable, and maintainable application design experience Consistent documentation Moderate development (wiring) speed Debugging and testing 7

8 CLD Exam Theme Exams are based on a sequencer type application Step order is configurable via an input file or user interface Timing is an essential aspect of the application Output or log file may be required Application must respond to user interface activity within 100 ms 8

9 CLD Exam Theme Scenario Sequencer Step 1 Execute: x secs Start Step 2 Execute: y secs Program design should be scalable to adapt to additional steps Step 3 Execute: z secs 9

10 Wait for k secs CLD Exam Theme Scenario Sequencer Step 1 Execute: x secs Wait for m secs Start Step 2 Execute: y secs Wait for n secs Program design should be scalable to adapt to additional steps Step 3 Execute: z secs 10

11 Wait for k secs CLD Exam Theme Scenario Sequencer *.csv / *.ini Step 2,10,2 Step 3,4,3 Step 1,6,5 Step 1 Execute: x secs Wait for m secs Start Step 2 Execute: y secs Wait for n secs Step 3 Execute: z secs 11

12 CLD Exam Design Design Patterns Timing Methods Development Style Documentation Error Handling 12

13 Design Patterns for CLD Applications Design Pattern Advantage Disadvantage State machine Handles sequence control Cannot handle storing of sequences May not be responsive enough to user interface events 13

14 State Machine Design Pattern 14

15 Design Patterns for CLD Applications Design Pattern Advantage Disadvantage State machine Handles sequence control Cannot handle storing of sequences May not be responsive enough to user interface events Queue based user interface Event Handler Extends state machine to store sequences Handles user interface events Does not allow intensive event or sequence processing User interface events need to be controlled by limiting access to front panel controls 15

16 Queue Based UI Event Handler Design Pattern 16

17 Design Patterns for CLD Applications Design Pattern Advantage Disadvantage State machine Handles sequence control Cannot handle storing of sequences May not be responsive enough to user interface events Queue based UI Event Handler Producer / Consumer with Events Extends state machine to store sequences Handles user interface events Responsive to user interface events Allows intensive event and sequence processing Does not allow intensive event or sequence processing User interface events need to be controlled by limiting access to FP controls Does not integrate non-user interface events well 17

18 Producer / Consumer Design Pattern 18

19 CLD Exam Design 1. Design Patterns 2. Timing Methods 3. Development Style 4. Documentation 5. Error Handling 19

20 Timing Methods for CLD Applications Timing Type Timing Method Applications Execution timing control Wait (ms) Wait Until Next (ms) multiple Regulate execution of state machine loop to allow other programs to run on the computer o Execution timing control allows us to regulate how quickly a loop executes on the processor 20

21 Execution Timing Control 21

22 Timing Methods for CLD Applications Timing Type Timing Method Applications Software timing control Get Date/Time in sec. Tick Count Good general purpose timing method for timing a sequence operation. Encapsulate in functional global or SubVI o Software timing control allows us to time a real-world operation to perform for a set time period. 22

23 Software Timing Control: Functional Global Functional Global Using Get/Date Time In secs function 23

24 Timing Methods for CLD Applications Timing Type Timing Method Applications Software timing control Get Date/Time in sec. Tick Count Express Elapsed time VI Good general purpose timing method for timing a sequence operation. Encapsulate in functional global or SubVI Measures Elapsed time with stop / reset control functions. Ready made solution!! Other useful Software timing control methods: Event Case Timeout Useful to stop an operation if no user activity is detected Synchronization VI Timeout - Useful for executing an operation at specific time periods 24

25 Software Timing Control: Elapsed Time Express VI Elapsed Time Express VI This is a subvi from the Car Wash sample exam 25

26 CLD Exam Design 1. Design Patterns 2. Timing Methods 3. Development Style 4. Documentation 5. Error Handling 26

27 CLD Application Style Small things that make a Big Difference!! Avoid the use of local variables when you can use a wire Use property nodes to modify control attributes and control values but not indicator values Type-define reused enums and data structures Close references if opened explicitly Avoid data coercion and default tunnels Avoid copies of code - Develop SubVI if code is reused Create readable block diagram Avoid unnecessary bends, overlapping objects, wires 27

28 Documenting CLD Applications Documentation Label wires to identify their use Example Label constants Description and tool tips for UI controls Block diagram comments VI / SubVI Properties» Documentation Tip: Brevity!! 28

29 CLD Exam Design 1. Design Patterns 2. Timing Methods 3. Development Style 4. Documentation 5. Error Handling 29

30 Error Handling in CLD Applications Stop VI on error when specified 30

31 CLD Exam: Preparation 1. Preparation Resources 2. Effective Exam Preparation 3. Exam taking tips 31

32 Preparation Resources Browse to southafrica. Enter CLD in the search Click on resulting link: On the CLD page, click on the following link (bottom): 32

33 Tips for Exam Preparation Test yourself: Time yourself through the sample exams Evaluate your solutions using the Exam Preparation Guide and the evaluation criteria given at the end of the guide Do better: Incorporate best practices in all your LabVIEW projects Use the generic sequencer model to develop new scenarios Improve your coding speed use Quick Drop! Find optimal ways to solve problems in LabVIEW 33

34 Tips for Exam Take a few minutes to plan your application Decide on the best main VI architecture for the application Decide which modules / SubVIs you will need to create Decide on the timing method Focus on getting most of the core functionality working Document the VI and SubVIs Clean up block diagram towards the end Pace yourself Time passes quickly when you are having fun!! 34

35 What happens after the exam? Exam proctor transmit exam project to NI for evaluation Candidates receive results in 4 weeks Exams are evaluated by two engineers Successful candidates receive logos and certificate by mail CLDs must recertify every two years or certify as CLA Unsuccessful candidates can improve on the feedback given on the evaluation sheet Re-attempt the exam when prepared 35

36 Additional Resources Darren Nattinger s practical tips on CLD readiness Re-watch the CLD Prep class online certification@ 36

37 Questions?