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SAE J2735-Draft-Rev29 [issued: 12-11-08]
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147 -
This is an SAE Motor Vehicle Council draft document of the DSRC committee, subject to change.
MSG
<XML>, and
DF
<XML>, and
MSG
<XML>, and
MSG
In addition, this item may be used by data structures in other ITS standards.
7.85 Data Element: DE_MsgCRC
Use: A two byte data element calculated over the payload bytes of the message (starting with the initial
sequence and ending with the last data element before the CRC itself and including all tag, length, and
values bytes found in between). Typically placed as the every last data element in the message. The
generating polynomial used is the "CRC-CCITT" commonly expressed as x^16 + x^12 + x^5 + 1. An
initial seed value of zero shall be used. Note that because the first byte of every DSRC message is never
zero (it is 0x30), framing errors due to incorrectly clocking initial zero values can not occur. Note that the
MSB byte is always transmitted first, following the typical ASN bytes order. When a well formed DSRC
message (including its last two bytes holding the CRC value) is decoded and input to the CRC process, the
resulting CRC should always be the value zero.
ASN.1 Representation:
MsgCRC ::= OCTET STRING (SIZE(2)) -- created with the CRC-CCCITT polynomial
XML Representation:
<xs:complexType name="MsgCRC" >
<xs:simpleContent>
<xs:annotation>
<xs:documentation>
created with the CRC-CCCITT polynomial
</xs:documentation>
</xs:annotation>
<xs:extension base="MsgCRC-string" >
<xs:attribute name="EncodingType" use="required">
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="base64Binary"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
<xs:simpleType name="MsgCRC-string">
<xs:restriction base="xs:base64Binary">
<xs:length value="3"/>
</xs:restriction>
</xs:simpleType >
Used By: This entry is directly used by the following 4 other data structures in this standard (record type,
descriptive name, ASN.1, and XML name (if present) of each):
DF
MSG
<XML>, and
MSG
<XML>, and
MSG
In addition, this item may be used by data structures in other ITS standards.