Add support of input registers while querying modbus sensor. (#7082)

* Add support of input registers while querying modbus sensor.

* Changed config option. Refactoring.

homeassistant/components/modbus.py

@@ -158,6 +158,15 @@ class ModbusHub(object):
                 count,
                 **kwargs)
 
+    def read_input_registers(self, unit, address, count):
+        """Read input registers."""
+        with self._lock:
+            kwargs = {'unit': unit} if unit else {}
+            return self._client.read_input_registers(
+                address,
+                count,
+                **kwargs)
+
     def read_holding_registers(self, unit, address, count):
         """Read holding registers."""
         with self._lock:

homeassistant/components/sensor/modbus.py

@@ -5,6 +5,7 @@ For more details about this platform, please refer to the documentation at
 https://home-assistant.io/components/sensor.modbus/
 """
 import logging
+import struct
 
 import voluptuous as vol
 
@@ -24,16 +25,28 @@ CONF_REGISTER = 'register'
 CONF_REGISTERS = 'registers'
 CONF_SCALE = 'scale'
 CONF_SLAVE = 'slave'
+CONF_DATA_TYPE = 'data_type'
+CONF_REGISTER_TYPE = 'register_type'
+
+REGISTER_TYPE_HOLDING = 'holding'
+REGISTER_TYPE_INPUT = 'input'
+
+DATA_TYPE_INT = 'int'
+DATA_TYPE_FLOAT = 'float'
 
 PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
     vol.Required(CONF_REGISTERS): [{
         vol.Required(CONF_NAME): cv.string,
         vol.Required(CONF_REGISTER): cv.positive_int,
+        vol.Optional(CONF_REGISTER_TYPE, default=REGISTER_TYPE_HOLDING):
+            vol.In([REGISTER_TYPE_HOLDING, REGISTER_TYPE_INPUT]),
         vol.Optional(CONF_COUNT, default=1): cv.positive_int,
         vol.Optional(CONF_OFFSET, default=0): vol.Coerce(float),
         vol.Optional(CONF_PRECISION, default=0): cv.positive_int,
         vol.Optional(CONF_SCALE, default=1): vol.Coerce(float),
         vol.Optional(CONF_SLAVE): cv.positive_int,
+        vol.Optional(CONF_DATA_TYPE, default=DATA_TYPE_INT):
+            vol.In([DATA_TYPE_INT, DATA_TYPE_FLOAT]),
         vol.Optional(CONF_UNIT_OF_MEASUREMENT): cv.string
     }]
 })
@@ -47,10 +60,12 @@ def setup_platform(hass, config, add_devices, discovery_info=None):
             register.get(CONF_NAME),
             register.get(CONF_SLAVE),
             register.get(CONF_REGISTER),
+            register.get(CONF_REGISTER_TYPE),
             register.get(CONF_UNIT_OF_MEASUREMENT),
             register.get(CONF_COUNT),
             register.get(CONF_SCALE),
             register.get(CONF_OFFSET),
+            register.get(CONF_DATA_TYPE),
             register.get(CONF_PRECISION)))
     add_devices(sensors)
 
@@ -58,17 +73,20 @@ def setup_platform(hass, config, add_devices, discovery_info=None):
 class ModbusRegisterSensor(Entity):
     """Modbus resgister sensor."""
 
-    def __init__(self, name, slave, register, unit_of_measurement, count,
-                 scale, offset, precision):
+    def __init__(self, name, slave, register, register_type,
+                 unit_of_measurement, count, scale, offset, data_type,
+                 precision):
         """Initialize the modbus register sensor."""
         self._name = name
         self._slave = int(slave) if slave else None
         self._register = int(register)
+        self._register_type = register_type
         self._unit_of_measurement = unit_of_measurement
         self._count = int(count)
         self._scale = scale
         self._offset = offset
         self._precision = precision
+        self._data_type = data_type
         self._value = None
 
     @property
@@ -88,16 +106,28 @@ class ModbusRegisterSensor(Entity):
 
     def update(self):
         """Update the state of the sensor."""
-        result = modbus.HUB.read_holding_registers(
-            self._slave,
-            self._register,
-            self._count)
+        if self._register_type == REGISTER_TYPE_INPUT:
+            result = modbus.HUB.read_input_registers(
+                self._slave,
+                self._register,
+                self._count)
+        else:
+            result = modbus.HUB.read_holding_registers(
+                self._slave,
+                self._register,
+                self._count)
         val = 0
         if not result:
             _LOGGER.error("No response from modbus slave %s register %s",
                           self._slave, self._register)
             return
-        for i, res in enumerate(result.registers):
-            val += res * (2**(i*16))
+        if self._data_type == DATA_TYPE_FLOAT:
+            byte_string = b''.join(
+                [x.to_bytes(2, byteorder='big') for x in result.registers]
+            )
+            val = struct.unpack(">f", byte_string)[0]
+        elif self._data_type == DATA_TYPE_INT:
+            for i, res in enumerate(result.registers):
+                val += res * (2**(i*16))
         self._value = format(
             self._scale * val + self._offset, '.{}f'.format(self._precision))