"outputStep" is not working correct

[Farhankhosravi]

Hi I recently used sTune library for a MAX6675 Furnace... it was hard to tune it manually as temperature changes very slow. So I decided to use sTune, and tried to edit configuration numbers as best as i can... but, my problem is on "outputStep"... this parameter is so weird. its default value is 50, and system will start with 50/1000 of heater output. this is so weak to even make my furance a little warm! so i increased it to 700, and test started and finished (but unfortunately every time it gaves a different p-i-d numbers.. anyway).. so: it is expected that sTune find best "outputStep" automatically; and do no need to be changed by user... and an IMPORTANT notice, if your setpoint is below current temprature (by mistake, running sTune in midde of work, etc) it wont notice that setpoint is below input and starts with adjusted "outputStep" value, makes your furnace over heated and makes burnings/etc.. please take a look on "outputStep". i think it needs a revision. Thanks

[Dlloydev]

Hello and thank you for your feedback.

The examples using the MAX6675 were for a PTC type heater. I plan on doing a revision later this year that includes examples using a regular thermal heater and provide improved documentation and easier to use interface.

Yes, sTune doesn't use setpoint while it determines the PID gains, so its important to set the tempLimit value prior to running the test.

To get more consistent PID numbers for a given outputStep (stepped power level), then its important that enough time has elapsed while resting at the outputStart value (power level) for the temperature to be stable before starting the test.

If needed, you can enforce a cool-down period between tests for the input temperature to stabilize. For example, use settleTimeSec = 1800; for 30 minutes cool-down time.

[InnuendoPi]

Hey,

I plan on doing a revision later this year that includes examples using a regular thermal heater and provide improved documentation and easier to use interface.

that would be helpful! I also stuck on testTimeSec, outputspan and outputstep. My environment: ESP8266, QuickPID, kettle (outputspan: 0..100% powerlevel, inductioncooker with seperat control functions), DS18B20 (inputspan 0..100°C). hints and tips are wlecome.