Fix slave id equal to 0

homeassistant/components/modbus/entity.py

@@ -32,6 +32,7 @@
 from homeassistant.helpers.restore_state import RestoreEntity
 
 from .const import (
+    ATTR_SLAVE,
     CALL_TYPE_COIL,
     CALL_TYPE_DISCRETE,
     CALL_TYPE_REGISTER_HOLDING,
@@ -79,14 +80,19 @@ def __init__(
         """Initialize the Modbus binary sensor."""
 
         self._hub = hub
-        self._slave = entry.get(CONF_SLAVE) or entry.get(CONF_DEVICE_ADDRESS, 1)
+        self._slave = (
+            entry.get(CONF_SLAVE)
+            if entry.get(CONF_SLAVE) is not None
+            else entry.get(CONF_DEVICE_ADDRESS, 1)
+        )
         self._address = int(entry[CONF_ADDRESS])
         self._input_type = entry[CONF_INPUT_TYPE]
         self._value: str | None = None
         self._scan_interval = int(entry[CONF_SCAN_INTERVAL])
         self._call_active = False
         self._cancel_timer: Callable[[], None] | None = None
         self._cancel_call: Callable[[], None] | None = None
+        self._attr_extra_state_attributes = {ATTR_SLAVE: self._slave}
 
         self._attr_unique_id = entry.get(CONF_UNIQUE_ID)
         self._attr_name = entry[CONF_NAME]

homeassistant/components/modbus/modbus.py

@@ -378,7 +378,9 @@ async def low_level_pb_call(
         self, slave: int | None, address: int, value: int | list[int], use_call: str
     ) -> ModbusPDU | None:
         """Call sync. pymodbus."""
-        kwargs: dict[str, Any] = {"slave": slave} if slave is not None else {"slave": 1}
+        kwargs: dict[str, Any] = (
+            {ATTR_SLAVE: slave} if slave is not None else {ATTR_SLAVE: 1}
+        )
         entry = self._pb_request[use_call]
         kwargs[entry.value_attr_name] = value
         try:

tests/components/modbus/test_init.py

@@ -1274,3 +1274,41 @@ async def test_no_entities(hass: HomeAssistant) -> None:
         ]
     }
     assert await async_setup_component(hass, DOMAIN, config) is False
+
+
+async def test_check_defaultslave(
+    hass: HomeAssistant,
+) -> None:
+    """Test default slave."""
+    config = {
+        DOMAIN: [
+            {
+                CONF_TYPE: TCP,
+                CONF_HOST: TEST_MODBUS_HOST,
+                CONF_PORT: TEST_PORT_TCP,
+                CONF_NAME: TEST_MODBUS_NAME,
+                CONF_SENSORS: [
+                    {
+                        CONF_NAME: "dummy",
+                        CONF_ADDRESS: 1234,
+                    },
+                    {
+                        CONF_NAME: "dummy_2",
+                        CONF_ADDRESS: 1234,
+                        CONF_SLAVE: 0,
+                    },
+                    {
+                        CONF_NAME: "dummy_3",
+                        CONF_ADDRESS: 1234,
+                        CONF_DEVICE_ADDRESS: 6,
+                    },
+                ],
+            }
+        ]
+    }
+    assert await async_setup_component(hass, DOMAIN, config)
+    await hass.async_block_till_done()
+    assert DOMAIN in hass.config.components
+    assert hass.states.get("sensor.dummy").attributes.get(ATTR_SLAVE) == 1
+    assert hass.states.get("sensor.dummy_2").attributes.get(ATTR_SLAVE) == 0
+    assert hass.states.get("sensor.dummy_3").attributes.get(ATTR_SLAVE) == 6