# Certification

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## 2017 CLAD Prep Guide: Hardware Q7

Hello Everyone,

I am very much confused by the CLAD 2017 Q7 hardware question "Which VI will only output all channels that have a value greater than 4 in them?" :

I wanted to know how to think about the problem because it looks like the major concept is row for channels and column for lines?

Any help would be greatly appreciated

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## Re: 2017 CLAD Prep Guide: Hardware Q7

You're dealing with waveforms, and not 2D arrays in any way.  So "row for channels and column for lines" doesn't seem to apply here.

Which one do you think the answer is?

Can you eliminate any of the answers and explain why?

I can eliminate 2.

I think between the other two, one is more right than the other and I believe it is because of some tricky wording in the question.

I don't want to give you my answer yet because I want to make sure you are able to think it through.

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## Re: 2017 CLAD Prep Guide: Hardware Q7

So I think  D. can be pretty easily be eliminated because it is incorrectly attempting conditional tunneling.

Waveform data: t0 timestamp, dt time between samples and Y 1D array of doubles that sample the signal.

Does that mean that option A is out too?

Beyond that I am not sure

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## Re: 2017 CLAD Prep Guide: Hardware Q7

**B is out because of waveform data

A could still be relevant based on datatype?

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## Re: 2017 CLAD Prep Guide: Hardware Q7

I am left to assume we want to keep the waveform output, so B and D are eliminated.  The question infers that a waveform should only output if it has a value greater than 4.  A replaces the value with an empty waveform while C eliminates that waveform all together.  A would make more sense if this was inside of an even bigger loop (your chart would still have a single plot corresponding to a single channel, where C would end up mixing plots among the different channels).  So I would say A would be the "more correct" answer.

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## Re: 2017 CLAD Prep Guide: Hardware Q7

Well according to the preparation guide the answer is C but it is still not obvious to me why.

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## Re: 2017 CLAD Prep Guide: Hardware Q7

C only outputs a waveform if it has a maximum value greater than 4.  That is exactly what the question asks for. "Which VI will only output all channels that have a value greater than 4 in them?"

A seems like a good answer, but it is outputting an empty waveform if it doesn't have a value greater than 4.  That is not the same thing as not outputting a waveform.  Id say this is the trick answer in the question.

B only outputs the greater than 4 values of a waveform, discarding any values less than 4.

D is only outputting the waveform if the very last data point of the waveform happens to be greater than 4.

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