@@ -0,0 +1,374 @@
+import unittest
+from unittest.mock import MagicMock
+
+from canopen.objectdictionary import ODVariable, ObjectDictionary
+from canopen.objectdictionary.datatypes import INTEGER8, UNSIGNED16, UNSIGNED32
+from canopen.profiles.p402 import BaseNode402, OperationMode, State402
+
+
+def _make_od():
+    """Create a minimal OD with DS402 objects for testing."""
+    od = ObjectDictionary()
+    # Controlword
+    var = ODVariable("Controlword", 0x6040)
+    var.data_type = UNSIGNED16
+    var.access_type = "rw"
+    od.add_object(var)
+    # Statusword
+    var = ODVariable("Statusword", 0x6041)
+    var.data_type = UNSIGNED16
+    var.access_type = "ro"
+    od.add_object(var)
+    # Modes of operation
+    var = ODVariable("Modes of operation", 0x6060)
+    var.data_type = INTEGER8
+    var.access_type = "rw"
+    od.add_object(var)
+    # Modes of operation display
+    var = ODVariable("Modes of operation display", 0x6061)
+    var.data_type = INTEGER8
+    var.access_type = "ro"
+    od.add_object(var)
+    # Supported drive modes
+    var = ODVariable("Supported drive modes", 0x6502)
+    var.data_type = UNSIGNED32
+    var.access_type = "ro"
+    od.add_object(var)
+    return od
+
+
+def _inject_tpdo(node, index, value):
+    """Simulate TPDO reception for a single OD object."""
+    fake_obj = MagicMock(index=index, raw=value)
+    fake_map = MagicMock()
+    fake_map.__iter__ = lambda s: iter([fake_obj])
+    node.on_TPDOs_update_callback(fake_map)
+
+
+class _FakeRpdoVar:
+    """Fake RPDO variable that calls a callback when raw is written."""
+
+    def __init__(self, on_write):
+        self._raw = 0
+        self._on_write = on_write
+        self.pdo_parent = MagicMock(is_periodic=False)
+
+    @property
+    def raw(self):
+        return self._raw
+
+    @raw.setter
+    def raw(self, value):
+        self._raw = value
+        self._on_write(value)
+
+
+class TestState402(unittest.TestCase):
+    """Tests for the State402 static helper and its lookup tables."""
+
+    def test_sw_mask_all_states_defined(self):
+        expected = {
+            "NOT READY TO SWITCH ON",
+            "SWITCH ON DISABLED",
+            "READY TO SWITCH ON",
+            "SWITCHED ON",
+            "OPERATION ENABLED",
+            "FAULT",
+            "FAULT REACTION ACTIVE",
+            "QUICK STOP ACTIVE",
+        }
+        self.assertEqual(set(State402.SW_MASK.keys()), expected)
+
+    def test_sw_mask_values_are_unique(self):
+        """Each state must produce a unique (mask, value) pair."""
+        pairs = list(State402.SW_MASK.values())
+        self.assertEqual(len(pairs), len(set(pairs)))
+
+    def test_cw_code_commands_round_trip(self):
+        """CW_CODE_COMMANDS and CW_COMMANDS_CODE should be inverses."""
+        for code, name in State402.CW_CODE_COMMANDS.items():
+            self.assertEqual(State402.CW_COMMANDS_CODE[name], code)
+        for name, code in State402.CW_COMMANDS_CODE.items():
+            self.assertEqual(State402.CW_CODE_COMMANDS[code], name)
+
+    def test_next_state_indirect_from_all_known_states(self):
+        """Every known state should have an indirect next state."""
+        for state in State402.SW_MASK:
+            result = State402.next_state_indirect(state)
+            # All states except OPERATION ENABLED should have a path
+            if state != "OPERATION ENABLED":
+                self.assertIsNotNone(result, f"No indirect path from {state}")
+                self.assertIn(
+                    result,
+                    State402.SW_MASK,
+                    f"Indirect state {result} is not a known state",
+                )
+
+    def test_next_state_indirect_specific_paths(self):
+        self.assertEqual(
+            State402.next_state_indirect("SWITCH ON DISABLED"), "READY TO SWITCH ON"
+        )
+        self.assertEqual(State402.next_state_indirect("READY TO SWITCH ON"), "SWITCHED ON")
+        self.assertEqual(State402.next_state_indirect("SWITCHED ON"), "OPERATION ENABLED")
+        self.assertEqual(State402.next_state_indirect("FAULT"), "SWITCH ON DISABLED")
+        self.assertEqual(State402.next_state_indirect("FAULT REACTION ACTIVE"), "FAULT")
+        self.assertEqual(
+            State402.next_state_indirect("QUICK STOP ACTIVE"), "SWITCH ON DISABLED"
+        )
+
+    def test_next_state_indirect_unknown_state(self):
+        self.assertIsNone(State402.next_state_indirect("NONEXISTENT"))
+
+    def test_transition_table_keys_are_valid_states(self):
+        known = set(State402.SW_MASK.keys()) | {"START", "DISABLE VOLTAGE"}
+        for from_state, to_state in State402.TRANSITIONTABLE:
+            self.assertIn(from_state, known, f"Unknown from-state: {from_state}")
+            self.assertIn(to_state, known, f"Unknown to-state: {to_state}")
+
+
+class TestBaseNode402State(unittest.TestCase):
+    """Test state property reading from simulated TPDO reception."""
+
+    def setUp(self):
+        self.node = BaseNode402(1, _make_od())
+
+    def _inject_statusword(self, sw):
+        """Simulate TPDO reception with the given statusword."""
+        _inject_tpdo(self.node, 0x6041, sw)
+
+    def test_state_from_statusword(self):
+        """Verify all state decoding from TPDO-received statusword."""
+        test_cases = [
+            (0x0000, "NOT READY TO SWITCH ON"),
+            (0x0040, "SWITCH ON DISABLED"),
+            (0x0021, "READY TO SWITCH ON"),
+            (0x0023, "SWITCHED ON"),
+            (0x0027, "OPERATION ENABLED"),
+            (0x0008, "FAULT"),
+            (0x000F, "FAULT REACTION ACTIVE"),
+            (0x0007, "QUICK STOP ACTIVE"),
+        ]
+        for sw, expected_state in test_cases:
+            with self.subTest(statusword=hex(sw)):
+                self._inject_statusword(sw)
+                self.assertEqual(self.node.state, expected_state)
+
+    def test_state_unknown_statusword(self):
+        self._inject_statusword(0xFFFF)
+        self.assertEqual(self.node.state, "UNKNOWN")
+
+    def test_is_faulted_true(self):
+        self._inject_statusword(0x0008)  # FAULT
+        self.assertTrue(self.node.is_faulted())
+
+    def test_is_faulted_false(self):
+        self._inject_statusword(0x0040)  # SWITCH ON DISABLED
+        self.assertFalse(self.node.is_faulted())
+
+    def test_controlword_read_raises(self):
+        with self.assertRaises(RuntimeError):
+            _ = self.node.controlword
+
+    def test_state_transition_sequence(self):
+        """Walk through the state machine by injecting TPDO statusword updates."""
+        expected_sequence = [
+            (0x0040, "SWITCH ON DISABLED"),
+            (0x0021, "READY TO SWITCH ON"),
+            (0x0023, "SWITCHED ON"),
+            (0x0027, "OPERATION ENABLED"),
+        ]
+        for sw, expected_state in expected_sequence:
+            self._inject_statusword(sw)
+            self.assertEqual(self.node.state, expected_state)
+
+    def test_state_fault_recovery_sequence(self):
+        """Simulate a fault recovery path via TPDO updates."""
+        self._inject_statusword(0x000F)  # FAULT REACTION ACTIVE
+        self.assertEqual(self.node.state, "FAULT REACTION ACTIVE")
+        self._inject_statusword(0x0008)  # FAULT
+        self.assertEqual(self.node.state, "FAULT")
+        self._inject_statusword(0x0040)  # SWITCH ON DISABLED
+        self.assertEqual(self.node.state, "SWITCH ON DISABLED")
+
+    def test_statusword_sdo_fallback(self):
+        """When no TPDO value is cached, statusword falls back to SDO."""
+        node = BaseNode402(1, _make_od())
+        node.sdo = MagicMock()
+        node.sdo.__getitem__ = MagicMock(return_value=MagicMock(raw=0x0040))
+        self.assertEqual(node.statusword, 0x0040)
+
+    def test_check_statusword_periodic_tpdo(self):
+        """check_statusword waits for periodic TPDO reception."""
+        self._inject_statusword(0x0040)
+        tpdo_ptr = MagicMock()
+        tpdo_ptr.pdo_parent.is_periodic = True
+        tpdo_ptr.pdo_parent.wait_for_reception.return_value = 1234.0
+        self.node.tpdo_pointers[0x6041] = tpdo_ptr  # type: ignore[assignment]
+        result = self.node.check_statusword()
+        tpdo_ptr.pdo_parent.wait_for_reception.assert_called_once()
+        self.assertEqual(result, 0x0040)
+
+    def test_check_statusword_periodic_tpdo_timeout(self):
+        """check_statusword raises on TPDO reception timeout."""
+        tpdo_ptr = MagicMock()
+        tpdo_ptr.pdo_parent.is_periodic = True
+        tpdo_ptr.pdo_parent.wait_for_reception.return_value = None
+        self.node.tpdo_pointers[0x6041] = tpdo_ptr  # type: ignore[assignment]
+        with self.assertRaises(RuntimeError):
+            self.node.check_statusword()
+
+    def test_check_statusword_non_periodic_tpdo(self):
+        """check_statusword reads SDO for non-periodic TPDO."""
+        tpdo_ptr = MagicMock()
+        tpdo_ptr.pdo_parent.is_periodic = False
+        self.node.tpdo_pointers[0x6041] = tpdo_ptr  # type: ignore[assignment]
+        self.node.sdo = MagicMock()
+        self.node.sdo.__getitem__ = MagicMock(return_value=MagicMock(raw=0x0023))
+        result = self.node.check_statusword()
+        self.assertEqual(result, 0x0023)
+
+
+class TestBaseNode402StateTransition(unittest.TestCase):
+    """Test state machine transitions with simulated TPDO/RPDO."""
+
+    def setUp(self):
+        self.node = BaseNode402(1, _make_od())
+        self.cw_log = []
+
+        def _on_cw_write(value):
+            self.cw_log.append(value)
+            # Simulate drive response: look up the transition and inject statusword
+            current = self.node.state
+            for (from_s, to_s), cw in State402.TRANSITIONTABLE.items():
+                if cw == value and from_s == current:
+                    if to_s in State402.SW_MASK:
+                        _, bits = State402.SW_MASK[to_s]
+                        self.node.tpdo_values[0x6041] = bits
+                    return
+
+        self.node.rpdo_pointers[0x6040] = _FakeRpdoVar(_on_cw_write)  # type: ignore[assignment]
+
+    def test_transition_to_operation_enabled(self):
+        """Walk from SWITCH ON DISABLED to OPERATION ENABLED via state setter."""
+        _inject_tpdo(self.node, 0x6041, 0x0040)  # SWITCH ON DISABLED
+        self.node.state = "OPERATION ENABLED"
+        self.assertEqual(self.node.state, "OPERATION ENABLED")
+        self.assertEqual(
+            self.cw_log,
+            [
+                State402.CW_SHUTDOWN,
+                State402.CW_SWITCH_ON,
+                State402.CW_OPERATION_ENABLED,
+            ],
+        )
+
+    def test_transition_from_fault(self):
+        """Walk from FAULT to SWITCH ON DISABLED via state setter."""
+        _inject_tpdo(self.node, 0x6041, 0x0008)  # FAULT
+        self.node.state = "SWITCH ON DISABLED"
+        self.assertEqual(self.node.state, "SWITCH ON DISABLED")
+        self.assertEqual(self.cw_log, [State402.CW_SWITCH_ON_DISABLED])
+
+    def test_transition_quick_stop(self):
+        """Transition from OPERATION ENABLED to QUICK STOP ACTIVE."""
+        _inject_tpdo(self.node, 0x6041, 0x0027)  # OPERATION ENABLED
+        self.node.state = "QUICK STOP ACTIVE"
+        self.assertEqual(self.node.state, "QUICK STOP ACTIVE")
+        self.assertEqual(self.cw_log, [State402.CW_QUICK_STOP])
+
+    def test_transition_fault_to_operation_enabled(self):
+        """Full path from FAULT through to OPERATION ENABLED."""
+        _inject_tpdo(self.node, 0x6041, 0x0008)  # FAULT
+        self.node.state = "OPERATION ENABLED"
+        self.assertEqual(self.node.state, "OPERATION ENABLED")
+        self.assertEqual(
+            self.cw_log,
+            [
+                State402.CW_SWITCH_ON_DISABLED,
+                State402.CW_SHUTDOWN,
+                State402.CW_SWITCH_ON,
+                State402.CW_OPERATION_ENABLED,
+            ],
+        )
+
+    def test_illegal_target_fault_raises(self):
+        _inject_tpdo(self.node, 0x6041, 0x0040)  # SWITCH ON DISABLED
+        with self.assertRaises(ValueError):
+            self.node.state = "FAULT"
+
+    def test_illegal_target_not_ready_raises(self):
+        _inject_tpdo(self.node, 0x6041, 0x0040)  # SWITCH ON DISABLED
+        with self.assertRaises(ValueError):
+            self.node.state = "NOT READY TO SWITCH ON"
+
+    def test_illegal_target_fault_reaction_raises(self):
+        _inject_tpdo(self.node, 0x6041, 0x0040)  # SWITCH ON DISABLED
+        with self.assertRaises(ValueError):
+            self.node.state = "FAULT REACTION ACTIVE"
+
+    def test_controlword_sdo_fallback(self):
+        """Controlword write falls back to SDO without RPDO configured."""
+        node = BaseNode402(1, _make_od())
+        node.sdo = MagicMock()
+        node.controlword = 0x0006
+        self.assertEqual(node.sdo[0x6040].raw, 0x0006)
+
+
+class TestBaseNode402OpMode(unittest.TestCase):
+    """Test operation mode reading via simulated TPDO."""
+
+    def setUp(self):
+        self.node = BaseNode402(1, _make_od())
+        tpdo_ptr = MagicMock()
+        tpdo_ptr.pdo_parent.is_periodic = False
+        self.node.tpdo_pointers[0x6061] = tpdo_ptr  # type: ignore[assignment]
+
+    def test_op_mode_read_all(self):
+        """Read each operation mode from TPDO-cached value."""
+        for code, name in OperationMode.CODE2NAME.items():
+            with self.subTest(code=code):
+                _inject_tpdo(self.node, 0x6061, code)
+                self.assertEqual(self.node.op_mode, name)
+
+    def test_op_mode_sdo_fallback(self):
+        """op_mode reads from SDO when TPDO pointer is missing."""
+        node = BaseNode402(1, _make_od())
+        node.sdo = MagicMock()
+        node.sdo.__getitem__ = MagicMock(
+            return_value=MagicMock(raw=OperationMode.PROFILED_POSITION)
+        )
+        self.assertEqual(node.op_mode, "PROFILED POSITION")
+
+    def test_op_mode_periodic_tpdo(self):
+        """op_mode waits for periodic TPDO then reads cached value."""
+        tpdo_ptr = MagicMock()
+        tpdo_ptr.pdo_parent.is_periodic = True
+        tpdo_ptr.pdo_parent.wait_for_reception.return_value = 1234.0
+        self.node.tpdo_pointers[0x6061] = tpdo_ptr  # type: ignore[assignment]
+        _inject_tpdo(self.node, 0x6061, OperationMode.HOMING)
+        self.assertEqual(self.node.op_mode, "HOMING")
+
+    def test_op_mode_periodic_tpdo_timeout(self):
+        """op_mode raises RuntimeError on TPDO reception timeout."""
+        tpdo_ptr = MagicMock()
+        tpdo_ptr.pdo_parent.is_periodic = True
+        tpdo_ptr.pdo_parent.wait_for_reception.return_value = None
+        self.node.tpdo_pointers[0x6061] = tpdo_ptr  # type: ignore[assignment]
+        with self.assertRaises(RuntimeError):
+            _ = self.node.op_mode
+
+
+class TestOperationMode(unittest.TestCase):
+    """Test OperationMode lookup tables."""
+
+    def test_code2name_name2code_round_trip(self):
+        for code, name in OperationMode.CODE2NAME.items():
+            self.assertEqual(OperationMode.NAME2CODE[name], code)
+
+    def test_all_named_modes_have_support_bit(self):
+        for name in OperationMode.NAME2CODE:
+            self.assertIn(name, OperationMode.SUPPORTED)
+
+
+if __name__ == "__main__":
+    unittest.main()