SAE INTERNATIONAL J2284™-5 SEP2016 Page 6 of 30
3.10 DATA BIT TIME
Length of a single bit in those parts of CAN FD messages where a dedicated separately configurable data bit time is used.
The data bit time is not used anywhere in Classical CAN messages and is not used in those CAN FD messages where the
BRS bit is dominant.
3.11 DATA LINK LAYER
Provides the reliable transfer of information across the Physical Layer. This includes message qualification and error
control.
3.12 DATA SAMPLE POINT (t
SAMPLE
)
The sample point is the time within the bit period at which the single bit sample captures the state of the bus. The
programmable bit sample point is located between t
SEG1
and t
SEG2
. Equation 1 shows the relationship of t
SAMPLE
to t
SEG2
:
(Eq. 1)
3.13 DIAGNOSTIC CONNECTOR
Provides the electrical connection between Off-Board and On-Board ECUs. For some vehicles, the diagnostic connector
is the SAE J1962 connector.
3.14 DISABLING OF DLC MATCHING
When this functionality is supported and active, then the bus transceiver will not compare message data length code (DLC)
values as to whether or not they match to configured DLC values when scanning messages for presence of valid wake-up
requests.
3.15 DOMINANT STATE
The dominant state is represented by a differential voltage greater than a minimum threshold between the CAN_L and
CAN_H bus wires. The dominant state overwrites the recessive state and represents a logic “0” bit value.
3.16 ELECTRONIC CONTROL UNIT (ECU)
An On- or Off-vehicle electronic assembly from which CAN SAE J2284-5 messages may be sent and/or received.
3.17 ECU Delay (t
ECU
)
An ECU’s loop delay includes the following four delays:
a. Transmitter Propagation Delay (t
TX
, this includes device delay and slew)
b. Receiver Propagation Delay (t
RX
)
c. Receiver Logic Delay (t
LOGIC
)
d. Common Mode Choke (t
CHK
, optional, Includes both Tx and Rx choke delays)
(Eq. 2)
t
ECU
t
TX
t
RX
t
LO GI C
t
CHK
+ +
+( )=
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