UT_RATE — Rate of change

Measures how fast a value is changing (level rise in a wet well, temperature climb,
pressure decay in a leak test) and alarms on rising or falling too fast.

Pins

Record UT_RATE_DATA

How it works

• Rate is the slope of the best straight line through the readings of the last
  window (a trend line), so noise largely cancels. A steady ramp gives exactly
  its rate at any task interval. Rate updates every scan.
• After a start, a Reset or a change of window, Rate is 0 and the alarms are
  off until one full window has been measured (ready).
• A sudden step shows as a short bump (peak about 1.7 × step ÷ window) lasting
  about one window. Use alarmDelay or a longer window to ride through steps.
• The alarms clear as soon as the rate is back within the limit.
• The window is kept as ten slices, so memory is the same at any task interval.
  Keep the window longer than a scan; a shorter one gives 0.
• A NaN or infinite In is ignored: Rate holds, badInput is set, and the time
  it lasted does not count.

Using it

WellRise(In := WetWellLevel, Data := WellRiseCfg);   (* riseLimit := 0.5 m/min *)
InflowAlarm := WellRise.RisingFast;