AcroPack Series AP560
CAN Bus Interface Module
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The data field is followed by the 16-bit Cyclic Redundancy Check (CRC) field.
This is used to check transmission errors by computing a 15-bit CRC sequence
from the previous bit stream (SOF, arbitration field, control field and data
field, excluding stuff bits). The last bit in the CRC field is the CRC delimiter bit
(always recessive).
After the CRC field is the Acknowledge Field (ACK Field). The first bit is the
ACK Slot bit. A transmitting node sends a recessive bit (logic 1) during the ACK
slot. Any node which receives the message error-free acknowledges the
reception by placing a dominant bit (logic 0) in the ACK slot, over-writing the
recessive bit of the transmitter. The final bit in the ACK field is a recessive ACK
delimiter bit. Therefore, the dominant ACK slot bit is surrounded on each side
by a recessive bit.
Each data frame is delimited by an End-Of-Frame field (EOF). The EOF consists
of seven recessive bits.
Following the EOF, there is a gap to the next frame called the Interframe
Space (IFS). The IFS consists of two bit fields, Intermission and Bus-Idle. The
Intermission consists of three recessive bits; however, the following notes
apply:
a)
detection of a dominant bit on the bus at the third slot is interpreted
as a SOF,
b)
detection of a dominant bit in either the first or second slots results in
generation of an overload frame (see below).
The bus idle period is of arbitrary length and consists of recessive bits. A
dominant bit detected during this period is interpreted as a SOF.
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...
