LabView Sprinkler Sample CLD exam feedback wanted

[LesPeters]

Starting to get ready for an upcoming LabView CLD exam, feedaback appreciated! 

[Blokk]

I had a little time to have a quick overview on your solution. Just some remarks:

-you must use a LV project to organize your files and keep them together, you would get point deduction for not using project I think

-Overusing data transfer via property nodes are against the guidelines. You have to give value to your indicators via wire.

-Why do not use a proper timer with shift registers (FGV or elapsed time Express VI in a subVI)? Your timer is very strange. However I am not sure what the grader would do...?

-Funcionality: the timer indicator should display the elapsed time dynamically. How it works now, it is not as described in the spec. document. See the above comment on proper timing. The system also does not react for low pressure and rain in the described way. Have a look on the provided solution, it will give you some idea.

So far these are the problematic things I catched...Also have a look at the provided solutions, so you will see examples for proper timing and indicator usage.

[Mathis_B]

Hi there,

generally: very good effort!

As Blokk said: you need to work in a project (makes life so much easier anyway). Try to reduce the amount of property nodes where possible. This has to be a trade off: if you realise during the exam that it would get ridiculously complicated to reduce the locations of where the indicators are written to to one then don't do it. Better to keep the code neat and tidy as it is and accept the deduction rather than tearing apart the code and getting loads more deductions for wire spagetti.

Good pratice is also to use standardised icons: header indicates functional module (e.g. File IO, Time, Ctrl, etc), while the bottom bit indicates what it exactly does.

Biggest problem is error handling: there is none! If an error occurs nothing happens but even worse the error gets never cleared and gets passed around (shift registers) stopping all modules from executing as nearly all modules have standard error in/out functionality and will simply be skipped. Fortunately it doesn't completely hang up the software as even if an error occurs the event structure will still be reacting to the stop button and the state machine will shut it down.

I would do the shut down of the state machine slightly different rather than comparing the state to Exit. I would wire a boolean out of each case: false in Init and run as well as true in Exit. I would then "or" the boolean with the error wire and wire it to the loop stop terminal. Outside of the state machine you will then need to place a simple error handler vi.

Your subVIs should also be implemented with standard error in/out functionality by putting all controls and indicators outside of an error case structure which only executes the code when no error is coming in.

Just a few minor points which might be worth about 4-5 pts (guesstimate)

good luck with the exam

BR Mathis

edit: agree with Blokk: make the timer a FGV!

edit 2: Error handling is actually a major problem and would potentially hang up the software. When you press start with an incoming error the "check water pressure sensor.vi" would return the default of zero from the variant to data which is smaller then 50 ... not stopping the loop. This would be avoided by wrapping an error case structure around everything (all controls and indicators need to be outside the case structure). In the case of an error everything would be skipped and you will need to return default values.

[LesPeters]

Thanks for your valuable feedback, all noted!

[LesPeters]

Thanks for taking the time to review my work.  You bring up some very good points as did Blokk.  The real challenge to the exam seems to be the time constraint.  Here at work I can typically take the extra time to develop a good solution.  I wonder if both of you could comment on your CLD exam experiences?

[Blokk]

Yes, the time is the biggest challenge. You really need a good strategy, unless you are faster than me 🙂 I had to skip some functionality due to my speed. In 5-6 hours all of the exam projects could be done very nicely and easily. I think this short time is intentional, they measure the experience level by the given short time.

Really try to get most points via the documentation and style. I saw an advice from another ex-exam taker that you can get "extra point" for documentation, if you create a "Documentation" folder and also add it to your project tree. And you create a full HTML report about your project and save all files (html, pngs) into this doc. folder.

You can read my experience here by the way:

http://forums.ni.com/t5/Certification/pls-review-my-car-wash-solution/m-p/3061624/highlight/true#M16...