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CLD-R Question 11

Why is the answer A? What's wrong with D? The only difference is that A forces the shutoff in a sequence (which is not stated as a requirement in the question)?

 

CLD-R Question 11.png

Message 1 of 10
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The key here is the word "reliably".  This not only means all of the outputs need to be turned off, but that they should be turned off in the same order each run.  D cannot guarantee the right order.


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Message 2 of 10
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Unless the question states explicity that it has to be shutdown in a certain sequence, I still believe that D will shut down the system reliably too. Should I assume that the variable engine will not let me write to the variables simultaneously?

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Message 3 of 10
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@SLee2004 wrote:

Unless the question states explicity that it has to be shutdown in a certain sequence, I still believe that D will shut down the system reliably too. Should I assume that the variable engine will not let me write to the variables simultaneously?


Yes, D will guarantee that all of the variables are set to false.  But I am pretty sure you want to make sure the outputs are disabled before shutting down power.  It isn't a matter of the variable engine, but an execution order.  If they are in parallel, you can't guarantee what will be shut off in what order.  That is why A is the "best" answer.


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Message 4 of 10
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Thanks for the reply. I wasn't thinking about the shutdown sequence the way the question is stated.

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Message 5 of 10
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The worst part is that none of the answers meet the "All Errors Reported" requirement.  Only the first error in the shutdown will be reported in all cases where multiple shutdown errors ocurr and any incoming errors are masked by the first shutdown error.

 

Better practice would be to ensure the incoming error will mask any shutdown errors.  Why? because if I went to shutdown due to an error the shutdown error is not important!  Standard "Close" functionality with Error In.


"Should be" isn't "Is" -Jay
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Message 6 of 10
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I tend to agree that this question is not well posed.  For example, why should we assume that Output Enable should be shut down after System Running?  Is it because of the way these variables are named?  Based on this, it seems more logical to disable the output and then bring the system down, which would make answer a incorrect.  If they want the system shut down in a particular sequence, it should be explicitly stated.  Otherwise, answers a and d seem equally valid.

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Message 7 of 10
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This is one of those questions where you need to mark the "most correct" answer.  As I stated before, reliably can not only mean "will happen", but also "will happen in this same exact order".  If you need consistant order, you have to go with A.  A is just the "most correct" answer.


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Message 8 of 10
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Hi, I know that the topic was issued in 2013, but I think that the answer is A because the shared variables don't have an error cluster as input. If an error cluster in input has an error, the shared variable will consequently not be updated (I tested this behaviour in LabVIEW 2014)
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Message 9 of 10
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@CristianLabview wrote:
Hi, I know that the topic was issued in 2013, but I think that the answer is A because the shared variables don't have an error cluster as input. If an error cluster in input has an error, the shared variable will consequently not be updated (I tested this behaviour in LabVIEW 2014)

The Question was for LabVIEW 2009.  That question was retired to a practice exam and the CLD-R exam no longer has a question that poorly written.  

 

DO KNOW the version of LabVIEW for which the exam is written!  It is part of the instructions!  New Features is a CLD-R exam topic.  Features newer than those on the exam can cost a pointSmiley Wink

 

Spoiler
Yeah, the IPE structure was introduced for the 2009 LV Version on the exam I took... and the "Correct" answer was obsoete by 2011 due to compiler optomizations.  Got that question wrong! (and that one only!) 

Better, Re-Cert by Points!


"Should be" isn't "Is" -Jay
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Message 10 of 10
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