Add support for new platform: climate.modbus (#12224)

* Added support for a new platform: climate.modbus

* Made changes based on code review.

* Made changes based on code review

* Made changes that were recommended in the pull request review.

* Fixed spacing line 144

* Added docstrings for the added helper functions.

* Fixed set_temperature() function to use a variable local to the function for the target temp.

* Fixed lint formatting error

* Modified logic when checking the target temperature, as well as fixing the setup_platform function

homeassistant/components/climate/modbus.py

@@ -0,0 +1,148 @@
+"""
+Platform for a Generic Modbus Thermostat.
+
+This uses a setpoint and process
+value within the controller, so both the current temperature register and the
+target temperature register need to be configured.
+
+For more details about this platform, please refer to the documentation at
+https://home-assistant.io/components/climate.modbus/
+"""
+import logging
+import struct
+
+import voluptuous as vol
+
+from homeassistant.const import (
+    CONF_NAME, CONF_SLAVE, ATTR_TEMPERATURE)
+from homeassistant.components.climate import (
+    ClimateDevice, PLATFORM_SCHEMA, SUPPORT_TARGET_TEMPERATURE)
+
+import homeassistant.components.modbus as modbus
+import homeassistant.helpers.config_validation as cv
+
+DEPENDENCIES = ['modbus']
+
+# Parameters not defined by homeassistant.const
+CONF_TARGET_TEMP = 'target_temp_register'
+CONF_CURRENT_TEMP = 'current_temp_register'
+CONF_DATA_TYPE = 'data_type'
+CONF_COUNT = 'data_count'
+CONF_PRECISION = 'precision'
+
+DATA_TYPE_INT = 'int'
+DATA_TYPE_UINT = 'uint'
+DATA_TYPE_FLOAT = 'float'
+
+PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
+    vol.Required(CONF_NAME): cv.string,
+    vol.Required(CONF_SLAVE): cv.positive_int,
+    vol.Required(CONF_TARGET_TEMP): cv.positive_int,
+    vol.Required(CONF_CURRENT_TEMP): cv.positive_int,
+    vol.Optional(CONF_DATA_TYPE, default=DATA_TYPE_FLOAT):
+        vol.In([DATA_TYPE_INT, DATA_TYPE_UINT, DATA_TYPE_FLOAT]),
+    vol.Optional(CONF_COUNT, default=2): cv.positive_int,
+    vol.Optional(CONF_PRECISION, default=1): cv.positive_int
+})
+
+_LOGGER = logging.getLogger(__name__)
+
+SUPPORT_FLAGS = SUPPORT_TARGET_TEMPERATURE
+
+
+def setup_platform(hass, config, add_devices, discovery_info=None):
+    """Set up the Modbus Thermostat Platform."""
+    name = config.get(CONF_NAME)
+    modbus_slave = config.get(CONF_SLAVE)
+    target_temp_register = config.get(CONF_TARGET_TEMP)
+    current_temp_register = config.get(CONF_CURRENT_TEMP)
+    data_type = config.get(CONF_DATA_TYPE)
+    count = config.get(CONF_COUNT)
+    precision = config.get(CONF_PRECISION)
+
+    add_devices([ModbusThermostat(name, modbus_slave,
+                                  target_temp_register, current_temp_register,
+                                  data_type, count, precision)], True)
+
+
+class ModbusThermostat(ClimateDevice):
+    """Representation of a Modbus Thermostat."""
+
+    def __init__(self, name, modbus_slave, target_temp_register,
+                 current_temp_register, data_type, count, precision):
+        """Initialize the unit."""
+        self._name = name
+        self._slave = modbus_slave
+        self._target_temperature_register = target_temp_register
+        self._current_temperature_register = current_temp_register
+        self._target_temperature = None
+        self._current_temperature = None
+        self._data_type = data_type
+        self._count = int(count)
+        self._precision = precision
+        self._structure = '>f'
+
+        data_types = {DATA_TYPE_INT: {1: 'h', 2: 'i', 4: 'q'},
+                      DATA_TYPE_UINT: {1: 'H', 2: 'I', 4: 'Q'},
+                      DATA_TYPE_FLOAT: {1: 'e', 2: 'f', 4: 'd'}}
+
+        self._structure = '>{}'.format(data_types[self._data_type]
+                                       [self._count])
+
+    @property
+    def supported_features(self):
+        """Return the list of supported features."""
+        return SUPPORT_FLAGS
+
+    def update(self):
+        """Update Target & Current Temperature."""
+        self._target_temperature = self.read_register(
+            self._target_temperature_register)
+        self._current_temperature = self.read_register(
+            self._current_temperature_register)
+
+    @property
+    def name(self):
+        """Return the name of the climate device."""
+        return self._name
+
+    @property
+    def current_temperature(self):
+        """Return the current temperature."""
+        return self._current_temperature
+
+    @property
+    def target_temperature(self):
+        """Return the temperature we try to reach."""
+        return self._target_temperature
+
+    def set_temperature(self, **kwargs):
+        """Set new target temperature."""
+        target_temperature = kwargs.get(ATTR_TEMPERATURE)
+        if target_temperature is None:
+            return
+        byte_string = struct.pack(self._structure, target_temperature)
+        register_value = struct.unpack('>h', byte_string[0:2])[0]
+
+        try:
+            self.write_register(self._target_temperature_register,
+                                register_value)
+        except AttributeError as ex:
+            _LOGGER.error(ex)
+
+    def read_register(self, register):
+        """Read holding register using the modbus hub slave."""
+        try:
+            result = modbus.HUB.read_holding_registers(self._slave, register,
+                                                       self._count)
+        except AttributeError as ex:
+            _LOGGER.error(ex)
+        byte_string = b''.join(
+            [x.to_bytes(2, byteorder='big') for x in result.registers])
+        val = struct.unpack(self._structure, byte_string)[0]
+        register_value = format(val, '.{}f'.format(self._precision))
+        return register_value
+
+    def write_register(self, register, value):
+        """Write register using the modbus hub slave."""
+        modbus.HUB.write_registers(self._slave, register, [value, 0])