Bynk uses "Virtual Pins" to pass data between the App and the hardware.
|Moisture level of the grow bed
|Min Humidity Level
|Graph (Moisture level of grow bed)
The Blynk Library calls BLYNK_WRITE(Virtual Pin#) when the appropriate virtual pin value is changed by the app.
In my Firmware once the function is called I store the Value of the Vpin in the appropriate variable for use later.
As an example
* sets the temperature level for the fans to come on
maxTemp = param.asInt();
Serial.print ("Temp Set ");
Serial.println ( maxTemp);
every time the temp Slider is moved the value of the slider is stored and printed.
Unfortunately the value stored will be lost if the NodeMCU is ever reset - ## Need to store the values in Flash to be read when the unit reboots ##