Tag: CLD

Preparing for LabVIEW CLD exam (2)

I should have written this post one month ago before I took the CLD exam. The good news is I passed that. 🙂 80 out of 100, which is more than I expected (I’ll carry on this later).

I will not talk anything about the exam itself, as I promised in the exam. But just finish the things I prepared for the exam.
1. I found this blog “Pass your CLD/CLA exams the JKI way” very useful, which gave me the confidence of carry on preparing for the exam. Though I didnt use it at the end, it is very helpful for preparing your own template.
2. Timing problem. The timing problem is the tricky part in the exam, such as how to pause/resume/restart your state machine. I made a subVI beforehand to practise it. You can find it here.
3. Pay attention to the documentation, which should be the easiest part to get the credits.
4. If you can finish the sample exams within 4 hours, I’m pretty sure you can pass the exam. If you can finish that within 3 hours, you can get the full marks in the exam.

Since I didn’t finish all the functions during the exam, I felt bad about it. But it turned out I got almost full marks in the programming style and the documentation parts, which saved my life. I didn’t have the plan to take the CLA before, but now I’m considering about it.

Good luck to all of you who are going to take the CLD exams.

Related post: Preparing for LabVIEW CLD exam (1)

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Pause and continue the time with Elapsed time.vi in LabVIEW

Elapsed Time.vi is a very useful Express vi which returns the elapsed time and can be reseted. Unfortunately there is no pause function in Elapsed Time.vi ( LabVIEW 8.5 to 2009). I had been looking for the examples of pausing and continuing the time in LabVIEW, but there seems not be a simple one.
So I created this myself. It is not efficient in term of excecution time, but it is simple to be made from scratch and memorized.

Basically the shift registers are used to store the previous elapsed time. When it is in the false (run) case, the elapsed time is added to the ‘total elapsed time’. When the vi in the true (pause) case, the total elapsed time is transferred to the start time and the Elapsed Time.vi is reseted (stopped). Hope this will be helpful. 🙂

 

———————–In response to Mark’s question——————————–

So I added the reset function for this SubVI:

When you reset the clock, you simply ‘reset’ it and send ‘0’ to elapsed time. Hope it helps.

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Preparing for LabVIEW CLD exam (1)

So I registered for the CLD (Certified LabVIEW Developer) exam on 5th August. I knew LabVIEW when I started my Ph.D in November 2007 and have been using it for 3 years. I had been “learning” LabVIEW for 2 years. In the 3rd year I was more of using it instead of learning more things. Since it is said that the CLD is suitable for users with experience of “a year and a half”, I think it is fair for me to take the exam.
There are 4 exam samples online (link) and they are said to be very similar to the actual exam. Also Darren’s note on CLD is very helpful (link). So my plan is taking the examples as the real exam and finding the knowledge I’m not aware of. One exam lasts 4 hours and I have to use one weekend to finish one. So the examples have to be finished before end of June (5 weeks to go).
I took the “ATM machine” examle last week and failed to finish it in time. I think that might be the most difficult one among the 4 (or not?). Anyway, fortunetly there is still time to fix that problem.

Here are what I have learned from the examples, and I will add more thoughts as the practice goes on. Hope this can be helpful:
1. We do not need to install any module beside LabVIEW to take the exam. It tests your coding ability instead of your module experience.
2. The logic of the exam is very complicated.
3. For me, the exam could be finished if more time (maybe 2 more hours) was given. Thus the challenge is how to finish it in the limited time. You cannot do that without good practice.
4. Use state machine, as stated in the exam. And I found the queue operation is not necessary in these 4 exam samples.
5. The project manager is not neccessary for there won’t be many versions of your code.
6. Folders named “SubVI” and “Control” are useful. Put the Top_level.vi in the top folder.
7. There could be file read/write operation, and thus we need to master how to manipulate the file path and text-related functions.
8. Draw the states clearly before coding, which saves you a lot of time later (Or, do not code before the logic of states is clear).
9. Because of 8, pens of different colours are very helpful (but is it allowed to bring our own pens?).
10. Set the preference of block diagram a ‘comfortable’ way. E.g. untick Display terminals as icons; untick Show dots at joints; untick Auto wiring; tick Default SubVI terminal as required.
11. Quick drop saves you time.
12. Save the code frequently in case of unknown situations.
13. If you cannot finish the code, create all SubVIs only with front panels. At least the program could be ran (with some missing functions).
14. Knowledge of timed loop and control reference are necessary (Update: I added an example in this post).

FYI: this is my drawing of the state machine. It will be messier if there was just one colour.

I will carry on the exam simulation this weekend and my timeline is: finish the state diagram within 1 hour; Create the structure and SubVIs with only terminals and descriptions in 1 hour; try to finish all the functions in 2 hours.

Good luck to me.

Update: Related post Preparing for LabVIEW CLD exam (2)

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