Index: leahi_dialin/common/msg_defs.py
===================================================================
diff -u -r41de945f9c773e54e965e80d9e46def828beb732 -r6c90336ac2cd8cf34ac620cff431a847d9ddf557
--- leahi_dialin/common/msg_defs.py	(.../msg_defs.py)	(revision 41de945f9c773e54e965e80d9e46def828beb732)
+++ leahi_dialin/common/msg_defs.py	(.../msg_defs.py)	(revision 6c90336ac2cd8cf34ac620cff431a847d9ddf557)
@@ -14,15 +14,13 @@
 #
 ############################################################################
 from enum import unique
-from ..utils.base import DialinEnum
+from ..utils.enums import DialinEnum
 from .msg_ids import MsgIds
+from .constants import MSG_HEADER_SIZE
 
+ACK_NOT_REQUIRED = [ ]
 
-ACK_NOT_REQUIRED = [
 
-]
-
-
 @unique
 class RequestRejectReasons(DialinEnum):
     REQUEST_REJECT_REASON_NONE = 0
@@ -75,9 +73,10 @@
     REQUEST_REJECT_REASON_TREATMENT_CANNOT_BE_RESUMED = 47
 RequestRejectReasons._str_list = {}
 
+
 class MsgFieldPositions:
     # Generic response msg field byte positions (where 32-bit data fields are used)
-    START_POS_FIELD_1 = 6  # Hardcoded for now to avoid cyclic import issue. See protocols.CAN.DenaliMessage class
+    START_POS_FIELD_1 = MSG_HEADER_SIZE         # Hardcoded for now to avoid cyclic import issue. See protocols.CAN.CanMessage class
     END_POS_FIELD_1 = START_POS_FIELD_1 + 4
     START_POS_FIELD_2 = END_POS_FIELD_1
     END_POS_FIELD_2 = START_POS_FIELD_2 + 4
@@ -139,7 +138,7 @@
 
 class MsgFieldPositionsFWVersions:
     # UI version message field positions
-    START_POS_MAJOR = 6 # Hardcoded for now to avoid cyclic import issue. See protocols.CAN.DenaliMessage class
+    START_POS_MAJOR = MSG_HEADER_SIZE       # Hardcoded for now to avoid cyclic import issue. See protocols.CAN.CanMessage class
     END_POS_MAJOR = START_POS_MAJOR + 1
     START_POS_MINOR = END_POS_MAJOR
     END_POS_MINOR = START_POS_MINOR + 1