Overrun limit with RT Box 2

Question

Hi,

What does happen, if I set the overrun limit very high, e.g. 100000 and my available cores are over 100 % CPU-load in steady state? I mean, I understand, there isn't enough time to calculate the whole source code within the time interval given in the coder options. But what exactly happens there? Does the execution of the program code cut when the step size is reached the code begins from start point to execute, or does it finish the execution but cut it anywhere else?

And what happens if the CPU-load exceeds just in some time instants, e.g. when triggering (autotriggering) a scope? Do I get inaccuracies in my values?

Thanks in advance!

Answer 1

The behavior with more than 100% CPU load is undefined. It depends on a number of settings, in particular the multitasking settings. In practice, you should not make any assumptions on the behavior if overruns occur. Things that can happen when an overrun occurs are

• Output values may become inconsistent (some may have been updated while others have not)
• Input values may become inconsistent (some calculations might use newer input values than previous calculations in the same step)
• Steps may be missed/skipped

To clarify, the CPU load shown is always the maximum step time that was encountered in the update interval. A value of 100% means that during the last second or so there was at least one step that took 100% CPU time to complete.