Rule to calculate Windspeed

[spranz]

Hey, my actuall Project is to build a weatherstation with espeasy.
To measure the windspeed i have an aneometer with a Hallsensor where i measure with a pulsecounter on D1. (one pulse = 30cm)
Now i need a rule to calculate the windspeed out of the Time Variable from the pulsecounter.
And store it in a dummy device.
I have no errors in my log, but also no value in my dummy device. Can anyone help me to fix my code?

Code: Select all

on Windgeschwindigkeit#Count do
  // Zeit in Millisekunden aus der Variablen lesen
  Let [Zeit_ms]=[Windgeschwindigkeit#Time]

  // Zurückgelegte Strecke in Kilometern (30 cm = 0.0003 km)
  Let [Strecke_km]=0.0003

  // Zeit von Millisekunden in Stunden umrechnen
  Let [Zeit_ms]/3600000

 Let [Zeit_h]=[Zeit_ms]

  // Geschwindigkeit in km/h berechnen
  Let [Geschwindigkeit_kmh]=[Strecke_km]/[Zeit_h]

  // Ergebnis in einer Variablen speichern (angenommen, Dummy-Device in Task 7, Feld 1)
  TaskValueSet 7,1,[Geschwindigkeit_kmh]
endon

[TD-er]

How did you get to this syntax for those lines with "Let" ? Some Chat-GPT like suggestion?
In ESPEasy, the [...#...] syntax is being translated into a numerical value when parsing a rules line. See: https://espeasy.readthedocs.io/en/lates ... -notations
Also the '=' is not part of the command syntax.

You should use a numerical index to store a variable.
Ton is working on an extension to this to allow named variables, but that has not yet been included in an official build yet.

For internal variables, see: https://espeasy.readthedocs.io/en/lates ... -variables

Code: Select all

on Windgeschwindigkeit#Count do
  // Zeit in Millisekunden aus der Variablen lesen
  //   Let [Zeit_ms]=[Windgeschwindigkeit#Time]
  // Zeit von Millisekunden in Stunden umrechnen
  //  Let [Zeit_ms]/3600000
  //  Let [Zeit_h]=[Zeit_ms]
  // Zurückgelegte Strecke in Kilometern (30 cm = 0.0003 km)
  //  Let [Strecke_km]=0.0003
  // Geschwindigkeit in km/h berechnen
  //  Let [Geschwindigkeit_kmh]=[Strecke_km]/[Zeit_h]
  //
  // Factor: 
  //  0.0003 / (time / 3600000)
  // Simplify:
  // (3600000 * 0.0003) / t  ->  1080 / t
  if [Windgeschwindigkeit#Time] > 0
    let,1,1080/[Windgeschwindigkeit#Time]
  else
    let,1,0  // No measured time
  endif

  // Ergebnis in einer Variablen speichern (angenommen, Dummy-Device in Task 7, Feld 1)
  TaskValueSet 7,1,[var#1]
endon

Added bonus:
See the system variables page (tools->System variables) at the standard conversions.
When you have a display, or need to write it to log, you can also print the windspeed (and direction when present) like this:

Code: Select all

let,2,[var#1]/3.6 // Convert to meter/sec
logentry,"Windspeed: [var#1] km/h, [var#2] m/s, %c_ms2Bft%([var#2])"
// For wind direction, use:
// "Wind Dir.: %c_w_dir%(123.4)"  --> "Wind Dir.: ESE"

[Ath]

And to make these rules portable to other devices, you can set a Dummy Device using its name/valuename:

Code: Select all

  // Ergebnis in einer Variablen speichern (angenommen, Dummy-Device in Task 7, Feld 1)
  TaskValueSet ThingSpeak_2,Windgeschwindigkeit,[var#1]

NB: These names are not case-sensitive.

[spranz]

Yes, it was a suggestion from ChatGPT
I also tried to find answers from google but without any functional code.
I tried out your code, but in the variable for the speed, there was no value at the end. Without any errors in the log.
Something ist wrong i think.

I modyfied the code:

Code: Select all

 on Windgeschwindigkeit#Time do
 let,1,1440/[Windgeschwindigkeit#Time]
  TaskValueSet,7,1,[var#1]
endon

with this it is calculating the value. I think something is wrong with the IF loop?
A zero when there is no windspeed would be nice, because at the moment the last value stays without changing from the counter.