ezeio2:expref:start

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ezeio2:expref:start [2020-11-12 22:52] – johparezeio2:expref:start [2022-11-16 23:50] (current) – [Field expressions] andreh
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 Since we are looking for kW-hours, we need to divide the momentary power with 36000 (3600 seconds in an hour, and we are re-evaluating 10 times per second). Since we are looking for kW-hours, we need to divide the momentary power with 36000 (3600 seconds in an hour, and we are re-evaluating 10 times per second).
  
 +=== Example: Signal filter ===
 +
 +{{ :ezeio2:expref:iirresponsegraph.png?400|}}If data from a register (or other field) includes a lot of noise and needs to be filtered over time, a simple field expression can be used to implement a IIR filter function:
 +
 +<code javascript>( f(THIS)*99 + r(1,1) )/100</code>
 +
 +Knowing that the expression evaluated 10 times per second, we are keeping 99% of the value, and adding 1% from the signal every 100ms. Thus the response time for this filter is about 7s for a 3dB (50%) response.
 ==== Reverse expressions ==== ==== Reverse expressions ====
  
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  • Last modified: 2020-11-12 22:52
  • by johpar