M_ANA function: How to DHm
my question is, how to use DHm limits in the M_ANA-function. I don`t undersatnd to configure this limit. e.g. I want to monitor the steam-pressure speed change.
Is there a fromula to calculate the limit I need to set in the M_ANA-function.
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DHm expects a per minute change limit (DHs second, DHh hour)
positive limits detect high risings, negative limits detect high drops.
M_ANA calculates the difference of the IN value of the current execution with the value of the previous execution. It then normalizes it to the selected time base for the rate, considering the cycle time.
If your input would be in bar, your limit would be bar/Minute. Rises and drops need separate limits.
You can find more information in the help (click Help in the M_ANA configuration dialog): See section Functions and Function blocks : General description and overview : Hints on parameter definition of the blocks