I thought I’d post about the couple of things I had to fix to get the setting of the Nest thermostat mode and target temperature working. First, I was setting the mode in lower case (“off”, “heat”), as in WWN, whereas for SDM it needs to be upper case. Second, I had the item definition for the target temperature wrong.
Originally I had:
"Nest: Main bedroom set point [%.2f °C]"
What worked was:
"Nest: Main bedroom set point [%.1f %unit%]"
The %unit% bit may or may not be important. What definitely got it working was reducing the precision to one decimal place.