AcroPack Series AP560
CAN Bus Interface Module
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Extended Data Frame
The extended data frame is shown in Figure 3. In this frame format, SOF is
followed by a 32-bit arbitration field consisting of a 29-bit identifier, ID28 -
ID0. The first 11 most significant bits of the ID are known as the base
identifier. This is followed by the Substitute Remote Request (SRR) bit, which
is defined as recessive. Following the SRR bit is the IDE bit, which is defined as
recessive for extended data frames. Note that the SRR bit is in the same slot
as the RTR bit of the standard frame and the IDE bits are also in corresponding
slots. This means if standard and extended identifier data frames with
identical base identifiers are transmitted simultaneously, the standard
identifier data frame will win arbitration (see Bitwise Arbitration section
below).
The SRR and IDE bits are followed by the remaining 18 bits of the identifier
(extended ID) and the last bit of the arbitration field is the RTR bit. The RTR bit
has the same function as in the standard frame format.
Following the arbitration field is the 6-bit control field. The first two bits, r1
and r0, are specified by the CAN protocol as reserved bits for future
expansion. Both these bits must be transmitted dominant, but receivers must
be able to receive all combinations of dominant or recessive bits. The final 4
bits of the control field is the data length code (DLC). The binary value of this
4-bit field specifies the number of data bytes in the data payload (0 - 8 bytes).
Note:
All binary combinations greater than or equal to <1 0 0 0> specify 8
bytes of data. The remaining fields of the extended data frame (Data field,
CRC field, acknowledge field, EOF field and IFS field) are constructed in the
same way as the standard frame format.
Содержание AcroPack AP560
Страница 28: ...AcroPack Series AP560 CAN Bus Interface Module 28 Figure 2 Standard Data Frame...
Страница 30: ...AcroPack Series AP560 CAN Bus Interface Module 30 Figure 3 Extended Data Frame...
Страница 32: ...AcroPack Series AP560 CAN Bus Interface Module 32 Figure 4 Remote Frame...
Страница 34: ...AcroPack Series AP560 CAN Bus Interface Module 34 Figure 5 Error Frame...