PID Setpoint Profile VI (PID Toolkit) add error checking

[rgvdh@rdf]

The "profile" that this VI takes as an input is an array of time/value pairs.  Two sequential points with the same time make a step, two sequential points with increasing time make a ramp or soak.

Currently, two sequential points with decreasing time cause unpredictable behavior.  I suggest they should cause the VI to throw an error instead.

[AristosQueue (NI)]

I strongly suspect that not doing this check is deliberate. There is a constant tension in API design, particularly with math APIs, between performance vs. input checking. If I'm writing an algorithm where I know my inputs are good, I do not want the APIs that I call to waste time checking the inputs. This would be such a case.

[rgvdh@rdf]

>"I strongly suspect that not doing this check is deliberate."

In that case maybe write a "sanity check" or "coerce to sanity" vi?

At the very least, reword the documentation a bit:

"time (s) specifies the time values in the setpoint profile. Specify the time (s) values in ascending order." 

"ascending" should be "non descending" as you can have equal times for a step function.

Append "Descending times will result in unpredictable behavior."

[Darren]

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