Proposed fix for #436

canopen/objectdictionary/__init__.py

@@ -8,6 +8,7 @@
 
 from canopen.objectdictionary.datatypes import *
 from canopen.objectdictionary.datatypes_24bit import Integer24, Unsigned24
+from canopen.utils import pretty_index
 
 logger = logging.getLogger(__name__)
 
@@ -389,6 +390,13 @@ def decode_raw(self, data: bytes) -> Union[int, float, str, bytes, bytearray]:
             # Is this correct?
             return data.rstrip(b"\x00").decode("utf_16_le", errors="ignore")
         elif self.data_type in self.STRUCT_TYPES:
+            size = self.STRUCT_TYPES[self.data_type].size
+            if len(data) > size:
+                logger.warning("Excessive data in %s. Data type 0x%X expects %s bytes, got %s",
+                               pretty_index(self.index, self.subindex), self.data_type,
+                               size, len(data))
+                # Truncate the data to the expected size
+                data = data[:size]
             try:
                 value, = self.STRUCT_TYPES[self.data_type].unpack(data)
                 return value

canopen/sdo/client.py

@@ -115,23 +115,7 @@ def upload(self, index: int, subindex: int) -> bytes:
             When node responds with an error.
         """
         with self.open(index, subindex, buffering=0) as fp:
-            response_size = fp.size
-            data = fp.read()
-
-        # If size is available through variable in OD, then use the smaller of the two sizes.
-        # Some devices send U32/I32 even if variable is smaller in OD
-        var = self.od.get_variable(index, subindex)
-        if var is not None:
-            # Found a matching variable in OD
-            # If this is a data type (string, domain etc) the size is
-            # unknown anyway so keep the data as is
-            if var.data_type not in objectdictionary.DATA_TYPES:
-                # Get the size in bytes for this variable
-                var_size = len(var) // 8
-                if response_size is None or var_size < response_size:
-                    # Truncate the data to specified size
-                    data = data[0:var_size]
-        return data
+            return fp.read()
 
     def download(
         self,