Make sure any BaseNode always has a valid Node ID

canopen/node/base.py

@@ -8,7 +8,7 @@ class BaseNode:
     """A CANopen node.
 
     :param node_id:
-        Node ID (set to None or 0 if specified by object dictionary)
+        Node ID (set to 0 if specified by object dictionary)
     :param object_dictionary:
         Object dictionary as either a path to a file, an ``ObjectDictionary``
         or a file like object.
@@ -25,7 +25,9 @@ def __init__(
             object_dictionary = import_od(object_dictionary, node_id)
         self.object_dictionary = object_dictionary
 
-        self.id = node_id or self.object_dictionary.node_id
+        self.id = node_id or object_dictionary.node_id or 0
+        if not self.id or not 1 <= self.id <= 127:
+            raise ValueError("No valid Node ID provided, %r not in range 1..127")
 
     def has_network(self) -> bool:
         """Check whether the node has been associated to a network."""

canopen/node/local.py

@@ -18,6 +18,21 @@
 
 
 class LocalNode(BaseNode):
+    """Local CANopen node implementing essential communication services.
+
+    This does not provide a full-fledged communication logic stack, but needs
+    additional application logic to wire up the various services, such as
+    triggering PDO transmissions according to their communication parameters.
+
+    Notable exceptions are a local data store for SDO server access, and using
+    the Heartbeat Producer Time parameter to control Heartbeat transmission.
+
+    :param node_id:
+        Node ID (set to 0 if specified by object dictionary)
+    :param object_dictionary:
+        Object dictionary as either a path to a file, an ``ObjectDictionary``
+        or a file like object.
+    """
 
     def __init__(
         self,

canopen/node/remote.py

@@ -19,7 +19,7 @@ class RemoteNode(BaseNode):
     """A CANopen remote node.
 
     :param node_id:
-        Node ID (set to None or 0 if specified by object dictionary)
+        Node ID (set to 0 if specified by object dictionary)
     :param object_dictionary:
         Object dictionary as either a path to a file, an ``ObjectDictionary``
         or a file like object.

test/test_node.py

@@ -8,6 +8,25 @@ def count_subscribers(network: canopen.Network) -> int:
     return sum(len(n) for n in network.subscribers.values())
 
 
+class TestBaseNode(unittest.TestCase):
+
+    def test_valid_node_id(self):
+        node = canopen.node.base.BaseNode(1, canopen.ObjectDictionary())
+        self.assertEqual(node.id, 1)
+
+    def test_valid_node_id_from_od(self):
+        od = canopen.ObjectDictionary()
+        od.node_id = 2
+        node = canopen.node.base.BaseNode(0, od)
+        self.assertEqual(node.id, 2)
+
+    def test_invalid_node_id(self):
+        with self.assertRaises(ValueError):
+            _ = canopen.node.base.BaseNode(0, canopen.ObjectDictionary())
+        with self.assertRaises(ValueError):
+            _ = canopen.node.base.BaseNode(128, canopen.ObjectDictionary())
+
+
 class TestLocalNode(unittest.TestCase):
 
     @classmethod