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SAE J2735-Draft-Rev28 [issued: 11-10-08]
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29 -
This is an SAE Motor Vehicle Council draft document of the DSRC committee, subject to change.
XML Representation:
<xs:element name="basicSafetyMessage" type="BasicSafetyMessage"/>
<xs:complexType name="BasicSafetyMessage" >
<xs:sequence>
<!-- Header items -->
<xs:element name="msgID" type="DSRCmsgID" />
<!-- 1 byte
Part I, sent as a single octet blob -->
<xs:element name="blob1" type="BSMblob" />
<!-- The blob consists of the following 37 packed bytes:
-->
<!-- msgCnt MsgCount, -x- 1 byte
id TemporaryID, -x- 4 bytes
secMark DSecond, -x- 2 bytes
pos PositionLocal3D,
lat Latitude, -x- 4 bytes
long Longitude, -x- 4 bytes
elev Elevation, -x- 2 bytes
accuracy PositionalAccuracy, -x- 4 bytes
motion Motion,
speed Speed, -x- 2 bytes
heading Heading, -x- 2 byte
accelSet AccelerationSet4Way, -x- 7 bytes
control Control,
brakes BrakeSystemStatus, -x- 2 bytes
basic VehicleBasic,
size VehicleSize, -x- 3 bytes
Part II, sent as required -->
<xs:element name="events" type="EventFlags" minOccurs="0"/>
<!-- 2 bytes -->
<xs:element name="partTwo" type="PartTwoContent" minOccurs="0"/>
<xs:element name="localBasicSafetyMessage" type="local:BasicSafetyMessage"
minOccurs="0"/>
</xs:sequence>
</xs:complexType>
Remarks: This message is divided into two primary parts and uses the same BER-DER encoding system
in each. In the first part (those data elements which are always sent at all time) some data element have
been encoded as a well defined octet blob to enable concise encoding and conserve channel bandwidth. In
the second part, DER tags and lengths precede each possible defined element in the normal way. Any
Locally defined content can be added to the part two content in the normal way.. Developers of such local
content should take steps to avoid creating content with tags which could conflict with future revisions of
the standard (such tags should be in the local range of 128~255 to avoid conflict with the national
standard).
5.4 Message: MSG_CommonSafetyRequest
Use: The Common Safety Request message provides a means by which a vehicle participating in the
exchange of the basic safety message can unicast requests to other vehicles for addition information which
it requires for the safety applications it is actively running. Responding vehicles will (or may) add this
information to the appropriate place in the basic safety message when they broadcast it. Additional
operational concepts are explained further in other clauses of this standard.
Addition information (data elements and data frames) can be requested by this message to be placed into
the Part II sections of the basic safety message (Part I contains selected information that is always present
in every message without exception).
When a device receives a request for a data element it does not understand or support, or from a vehicle
with a spatial position or heading that it may choose to ignore, then that request is simply ignored.
ASN.1 Representation:
CommonSafetyRequest ::= SEQUENCE {
msgID DSRCmsgID,
msgCnt MsgCount OPTIONAL,