Index: scripts/update_package_script/update_package.py
===================================================================
diff -u -r7d3311666abd028a6f9e53f6f907356d4709bbde -r7f828c9d3822ff57f893144d74728a30fbd66f17
--- scripts/update_package_script/update_package.py	(.../update_package.py)	(revision 7d3311666abd028a6f9e53f6f907356d4709bbde)
+++ scripts/update_package_script/update_package.py	(.../update_package.py)	(revision 7f828c9d3822ff57f893144d74728a30fbd66f17)
@@ -13,7 +13,7 @@
     The class runs the firmware and FPGA updates
     """
     _TD_SW_UPDATE_PAYLOAD_BYTES = 256
-    _DD_SW_UPDATE_PAYLOAD_BYTES = 512
+    _DD_SW_UPDATE_PAYLOAD_BYTES = 256  #512
     _BROADCAST_MESSAGE_INTERVAL_S = 0.1
     _WAIT_FOR_BOOTLOADER_AFTER_RESET_S = 1.5
     _SW_UPDATE_STACK = 'stack_name'
Index: scripts/update_package_script/utilities.py
===================================================================
diff -u -r7d3311666abd028a6f9e53f6f907356d4709bbde -r7f828c9d3822ff57f893144d74728a30fbd66f17
--- scripts/update_package_script/utilities.py	(.../utilities.py)	(revision 7d3311666abd028a6f9e53f6f907356d4709bbde)
+++ scripts/update_package_script/utilities.py	(.../utilities.py)	(revision 7f828c9d3822ff57f893144d74728a30fbd66f17)
@@ -306,10 +306,9 @@
 
         @return none
         """
-        can_msg_bytes = self.convert_data_to_bytes('<B', self._LEAHI_MESSAGE_SYNC_BYTE)
-        can_msg_bytes += self.convert_data_to_bytes('<H', self._LEAHI_SEQ_1_BYTE)
-
         for msg_id, mail_box in self._leahi_mail_boxes.items():
+            can_msg_bytes = self.convert_data_to_bytes('<B', self._LEAHI_MESSAGE_SYNC_BYTE)
+            can_msg_bytes += self.convert_data_to_bytes('<H', self._LEAHI_SEQ_1_BYTE)
             # Loop through the Leahi mail boxes
             can_msg_bytes += self.convert_data_to_bytes('<H', msg_id)
             can_msg_bytes += self.convert_data_to_bytes('<B', 0) # Payload length is 0
@@ -346,7 +345,10 @@
         """
         if msg_type != '': self._msg_ack_nack_status[msg_type][0] = CanCommStatus.CAN_COMM_IN_PROGRESS.value
         packet = can.Message(arbitration_id=mail_box, data=data, is_extended_id=False)
-        self._can_bus.send(packet) # TODO handle can write error?
+        try:
+            self._can_bus.send(packet) # TODO handle can write error?
+        except Exception as e:
+            print(e)
 
     def _get_bootloader_ack_nack_resp(self, msg_type: str):
         """
@@ -438,8 +440,8 @@
 
         self._leahi_mail_boxes[self._LEAHI_SIGNAL_TD_UPDATE_AVAILABLE] = {self._STACK_SEND_UPDATE_MAIL_BOX: 0x041,
                                                                           self._STACK_RCV_RESP_MAIL_BOX: 0x040}
-        self._leahi_mail_boxes[self._LEAHI_SIGNAL_DD_UPDATE_AVAILABLE] = {self._STACK_SEND_UPDATE_MAIL_BOX: 0x041,
-                                                                          self._STACK_RCV_RESP_MAIL_BOX: 0x040}
+        self._leahi_mail_boxes[self._LEAHI_SIGNAL_DD_UPDATE_AVAILABLE] = {self._STACK_SEND_UPDATE_MAIL_BOX: 0x051,
+                                                                          self._STACK_RCV_RESP_MAIL_BOX: 0x050}
 
     @staticmethod
     def _convert_bytes_to_data(conversion: str, data: bytes):