pdo: Fix lower bound check in access by index (canopen-python#628)

The extended access patterns by communication parameter record index
only work for TPDOs. The lower bound check on the number range
excludes anything below 0x1600, thus RPDO communication parameters do
not work.

Extend test to cover access via 0x1400 and 0x1600 yielding the same
object.

Author: acolomb

canopen/pdo/base.py

@@ -46,7 +46,7 @@ def __getitem__(self, key: Union[int, str]):
                 raise KeyError("PDO index zero requested for 1-based sequence")
             if (
                 0 < key <= 512  # By PDO Index
-                or 0x1600 <= key <= 0x1BFF  # By RPDO / TPDO mapping or communication record
+                or 0x1400 <= key <= 0x1BFF  # By RPDO / TPDO mapping or communication record
             ):
                 return self.map[key]
         for pdo_map in self.map.values():

test/test_pdo.py

@@ -73,6 +73,8 @@ def test_pdo_getitem(self):
         self.assertIs(node.tpdo[0x2002], by_object_index)
         self.assertIs(node.pdo[0x1A00][0x2002], by_object_index)
 
+        self.assertIs(node.pdo[0x1400], node.pdo[0x1600])
+
         self.assertRaises(KeyError, lambda: node.pdo[0])
         self.assertRaises(KeyError, lambda: node.tpdo[0])
         self.assertRaises(KeyError, lambda: node.pdo['DOES NOT EXIST'])