I've found some typos on the serial api page.
S_DIMMER 4 Dimmable device of some kind V_STATUS (on/off), V_DIMMER (dimmer level 0-100), V_WATT
V_DIMMER needs to be V_PERCENTAGE
S_HVAC 29 Thermostat/HVAC device V_HVAC_SETPOINT_HEAT, V_HVAC_SETPOINT_COLD, V_HVAC_FLOW_STATE, V_HVAC_FLOW_MODE, V_HVAC_SPEED
V_HVAC_SETPOINT_COLD needs to be V_HVAC_SETPOINT_COOL