CLAD Prep Package, Section 2, Q6 - Parallel Loops

[Mark_Yedinak]

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@johntrich1971 wrote:

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@Bob_Schor wrote:

I don't understand Mark's point about the Timeout.

1. Why is only Loop 1 affected by the Timeout?  Both loops look very similar, differing only in the Sampling Rate and # Samples to acquire (both are set up the same way, so the acquisition time for Loop 1 should be 1 second, for Loop 2 2 seconds).
2. According to the DAQmx Help (which I consulted), Timeout specifies the time in seconds to wait for samples to become available.  What is hindering the Samples in either loop?
3. If (through some logic I haven't yet figured out) Mark is correct, then this question needs to be part of the CLA, not the CLAD, exam!

Bob Schor

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I understand what Mark is saying, but I just don't think that it applies here. Certainly if the hardware failed and no data were received then a timeout would be reached. However, it is implied in the question that the desired answer is what would occur under normal operating conditions, not in the unlikely case that the hardware failed at exactly the same time as the emergency stop was pressed.

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And implied requirements are the downfall of many systems.

[johntrich1971]

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@Mark_Yedinak wrote:

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@johntrich1971 wrote:

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@Bob_Schor wrote:

I don't understand Mark's point about the Timeout.

1. Why is only Loop 1 affected by the Timeout?  Both loops look very similar, differing only in the Sampling Rate and # Samples to acquire (both are set up the same way, so the acquisition time for Loop 1 should be 1 second, for Loop 2 2 seconds).
2. According to the DAQmx Help (which I consulted), Timeout specifies the time in seconds to wait for samples to become available.  What is hindering the Samples in either loop?
3. If (through some logic I haven't yet figured out) Mark is correct, then this question needs to be part of the CLA, not the CLAD, exam!

Bob Schor

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I understand what Mark is saying, but I just don't think that it applies here. Certainly if the hardware failed and no data were received then a timeout would be reached. However, it is implied in the question that the desired answer is what would occur under normal operating conditions, not in the unlikely case that the hardware failed at exactly the same time as the emergency stop was pressed.

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And implied requirements are the downfall of many systems.

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I guess that I don't look at a question on a CLAD test as a requirements document. If I were creating this code I would be concerned separately with what happens when I press the Emergency Stop button and what happens when a hardware failure occurs. If I need a true Emergency Stop it's not going to be dependent upon code, so this Emergency Stop is intended for normal operating conditions. So I would have a specification for how fast the program would stop under normal operating conditions and how fast the program would stop under an error condition (timeout).

[RavensFan]

The question does says "after the chart begins updating".

If this code was going to time out, then the chart would not begin updating.