Disregard OD variable description in SdoClient.upload()

canopen/sdo/base.py

@@ -148,7 +148,18 @@ def __init__(self, sdo_node: SdoBase, od: objectdictionary.ODVariable):
         variable.Variable.__init__(self, od)
 
     def get_data(self) -> bytes:
-        return self.sdo_node.upload(self.od.index, self.od.subindex)
+        data = self.sdo_node.upload(self.od.index, self.od.subindex)
+        response_size = len(data)
+
+        # 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
+        if self.od.fixed_size:
+            # Get the size in bytes for this variable
+            var_size = len(self.od) // 8
+            if response_size is None or var_size < response_size:
+                # Truncate the data to specified size
+                data = data[:var_size]
+        return data
 
     def set_data(self, data: bytes):
         force_segment = self.od.data_type == objectdictionary.DOMAIN

canopen/sdo/client.py

@@ -105,6 +105,10 @@ def abort(self, abort_code=0x08000000):
     def upload(self, index: int, subindex: int) -> bytes:
         """May be called to make a read operation without an Object Dictionary.
 
+        No validation against the Object Dictionary is performed, even if an object description
+        would be available.  The length of the returned data depends only on the transferred
+        amount, possibly truncated to the size indicated by the server.
+
         :param index:
             Index of object to read.
         :param subindex:
@@ -121,17 +125,8 @@ def upload(self, index: int, subindex: int) -> bytes:
             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 var.fixed_size:
-                # 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]
+        if response_size and response_size < len(data):
+            data = data[:response_size]
         return data
 
     def download(

test/test_sdo.py

@@ -95,16 +95,24 @@ def test_expedited_upload(self):
         ]
         trans_type = self.network[2].sdo[0x1400]['Transmission type RPDO 1'].raw
         self.assertEqual(trans_type, 254)
+
+        # Same with padding to a full SDO frame
+        self.data = [
+            (TX, b'\x40\x00\x14\x02\x00\x00\x00\x00'),
+            (RX, b'\x42\x00\x14\x02\xfe\x00\x00\x00')
+        ]
+        trans_type = self.network[2].sdo[0x1400]['Transmission type RPDO 1'].raw
+        self.assertEqual(trans_type, 254)
         self.assertTrue(self.message_sent)
 
     def test_size_not_specified(self):
         self.data = [
             (TX, b'\x40\x00\x14\x02\x00\x00\x00\x00'),
             (RX, b'\x42\x00\x14\x02\xfe\x00\x00\x00')
         ]
-        # Make sure the size of the data is 1 byte
+        # This method used to truncate to 1 byte, but returns raw content now
         data = self.network[2].sdo.upload(0x1400, 2)
-        self.assertEqual(data, b'\xfe')
+        self.assertEqual(data, b'\xfe\x00\x00\x00')
         self.assertTrue(self.message_sent)
 
     def test_expedited_download(self):
@@ -131,6 +139,17 @@ def test_segmented_upload(self):
         device_name = self.network[2].sdo[0x1008].raw
         self.assertEqual(device_name, "Tiny Node - Mega Domains !")
 
+    def test_segmented_upload_too_much_data(self):
+        # Server sends 5 bytes, but indicated size 4
+        self.data = [
+            (TX, b'\x40\x08\x10\x00\x00\x00\x00\x00'),
+            (RX, b'\x41\x08\x10\x00\x04\x00\x00\x00'),
+            (TX, b'\x60\x00\x00\x00\x00\x00\x00\x00'),
+            (RX, b'\x05\x54\x69\x6E\x79\x20\x00\x00'),
+        ]
+        device_name = self.network[2].sdo[0x1008].raw
+        self.assertEqual(device_name, "Tiny")
+
     def test_segmented_download(self):
         self.data = [
             (TX, b'\x21\x00\x20\x00\x0d\x00\x00\x00'),