MATLAB: Is there a difference between imported and exported ARXML file with Internal-Constrs

arxmlautosarEmbedded Coderexportedimportedinternal-constrs

Why is there a difference between imported and exported ARXML file with Internal-Constrs?

Best Answer

The issue seems to be that the physical range is not taken into account for that type along with the compu method. The type uses a compu method with an internal-to-physical conversion rule of 1/100, which maps on to an internal constraint of 0 to 32000. ceil(log2(32000-0)) is 15, implying we need 15 bits to represent the physical range of 0 to 320, not ceil(log2(320-0)) = 9, which is what we are importing as a numeric type and exporting to the ARXML (the physical constraint of 0 to 5.11 is thus re-calculated from the new internal constraint of 0 to 2^9-1, using the internal-to-physical conversion rule of 1/100).
If you add an internal constraint to "AB10477DC552B6F51113954083CCBE70" that sort of mirrors the physical constraint once the compu method is applied, e.g.
Imported ARXML file: (the addition of the constraint is in bold. It was previously unspecified, but still appeared in the exported ARXML file)
 <DATA-CONSTR UUID="54237557-8678-44b5-b265-189b2e402545">
 <SHORT-NAME>AB10477DC552B6F51113954083CCBE70</SHORT-NAME>
 <DATA-CONSTR-RULES>
 <DATA-CONSTR-RULE>
 <PHYS-CONSTRS>
 <LOWER-LIMIT INTERVAL-TYPE="CLOSED">0</LOWER-LIMIT>
 <UPPER-LIMIT INTERVAL-TYPE="CLOSED">320</UPPER-LIMIT>
 <UNIT-REF DEST="UNIT">/DataType/DataTypeUnits/KiloMtrPerHr</UNIT-REF>
 </PHYS-CONSTRS>
 *<INTERNAL-CONSTRS>
 <LOWER-LIMIT INTERVAL-TYPE="CLOSED">0</LOWER-LIMIT>
 <UPPER-LIMIT INTERVAL-TYPE="CLOSED">32000</UPPER-LIMIT>
 </INTERNAL-CONSTRS>*
 </DATA-CONSTR-RULE>
 </DATA-CONSTR-RULES>
 </DATA-CONSTR>
and we export this to:
Exported ARXML file:
 <DATA-CONSTR UUID="54237557-8678-44b5-b265-189b2e402545">
 <SHORT-NAME>AB10477DC552B6F51113954083CCBE70</SHORT-NAME>
 <DATA-CONSTR-RULES>
 <DATA-CONSTR-RULE>
 <PHYS-CONSTRS>
 <LOWER-LIMIT INTERVAL-TYPE="CLOSED">0</LOWER-LIMIT>
 <UPPER-LIMIT INTERVAL-TYPE="CLOSED">320</UPPER-LIMIT>
 <UNIT-REF DEST="UNIT">/DataType/DataTypeUnits/KiloMtrPerHr</UNIT-REF>
 </PHYS-CONSTRS>
 <INTERNAL-CONSTRS>
 <LOWER-LIMIT INTERVAL-TYPE="CLOSED">0</LOWER-LIMIT>
 <UPPER-LIMIT INTERVAL-TYPE="CLOSED">32767</UPPER-LIMIT>
 </INTERNAL-CONSTRS>
 </DATA-CONSTR-RULE>
 </DATA-CONSTR-RULES>
The internal constraint is 32767, which is 2^15-1, since we need 15 bits to represent the type. If you don't perform this change at all on round trip, you should just use 32767 as the upper limit.
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