Python Plugin Relative Humidity Actuator Example

in.idf

  PythonPlugin:Instance,
    Rel Hum Test,            !- Name
    Yes,                     !- Run During Warmup Days
    PythonTest,              !- Python Module Name
    Test;                    !- Plugin Class Name

  PythonPlugin:Variables,
    MyGlobalVariables,       !- Name
    RelHumFromOutputVar,     !- Variable Name 1
    RelHumFromActuator;      !- Variable Name 2

  PythonPlugin:OutputVariable,
    Rel Hum From Output Variable,   !- Name
    RelHumFromOutputVar,     !- Python Plugin Variable Name
    Averaged,                !- Type of Data in Variable
    SystemTimestep;          !- Update Frequency

  PythonPlugin:OutputVariable,
    Rel Hum From Actuator,   !- Name
    RelHumFromActuator,               !- Python Plugin Variable Name
    Averaged,                !- Type of Data in Variable
    SystemTimestep;          !- Update Frequency

  Output:Variable,*,Site Outdoor Air Relative Humidity,hourly;

  Output:Variable,Rel Hum From Output Variable,PythonPlugin:OutputVariable,hourly;

  Output:Variable,Rel Hum From Actuator,PythonPlugin:OutputVariable,hourly;

PythonTest.py

class Test(EnergyPlusPlugin):

    def __init__(self):
        super().__init__()

        # class member variables
        self.relhum_from_output_var_handle = None
        self.relhum_from_actuator_var_handle = None
        self.outdoor_air_relhum_handle = None
        self.outdoor_air_relhum_actuator_handle = None
        self.need_to_get_handles = True

    def get_handles(self, state):
        # get variable handles and save for later
        self.outdoor_air_relhum_handle = self.api.exchange.get_variable_handle(state,
                                                                               "Site Outdoor Air Relative Humidity",
                                                                               "Environment")
        self.outdoor_air_relhum_actuator_handle = self.api.exchange.get_actuator_handle(state,
                                                                                        "Weather Data",
                                                                                        "Outdoor Relative Humidity",
                                                                                        "Environment")
        self.relhum_from_output_var_handle = self.api.exchange.get_global_handle(state, "RelHumFromOutputVar")
        self.relhum_from_actuator_var_handle = self.api.exchange.get_global_handle(state, "RelHumFromActuator")
        self.need_to_get_handles = False

    def on_begin_zone_timestep_before_set_current_weather(self, state) -> int:

        # initialize if the API is ready
        if self.need_to_get_handles:
            if self.api.exchange.api_data_fully_ready(state):
                self.get_handles(state)
            else:
                return 0

        # get the current relative humidity value from the output variable, assign it to the global variable
        current_relhum = self.api.exchange.get_variable_value(state, self.outdoor_air_relhum_handle)
        self.api.exchange.set_global_value(state, self.relhum_from_output_var_handle, current_relhum)

        # set the new ODA relhum value via the actuator and assign it to the global variable
        new_relhum = 34.56789

        self.api.exchange.set_actuator_value(state, self.outdoor_air_relhum_actuator_handle, new_relhum)
        self.api.exchange.set_global_value(state, self.relhum_from_actuator_var_handle, new_relhum)
        return 0