Rainbow Electronics T89C51CC01 - Manual (Page 78)

78
T89C51CC01
Rev. D – 17-Dec-01
15.6 Fault Confinement With respect to fault confinement, a unit may be in one of the three following status:
• error active,
• error passive,
• bus off.
An error active unit takes part in bus communication and can send an active error frame
when the CAN macro detects an error.
An error passive unit cannot send an active error frame. It takes part in bus communica-
tion, but when an error is detected, a passive error frame is sent. Also, after a
transmission, an error passive unit will wait before initiating further transmission.
A bus off unit is not allowed to have any influence on the bus.
For fault confinement, two error counters (TEC and REC) are implemented.
See CAN Specification for details on Fault confinement.
Figure 36. Line error mode
TEC>255
Error
Active
Error
Passive
Bus
Off
Init.
TEC<127
and
REC<127
TEC>127
or
REC>127
128 occurrences
of
11 consecutive
recessive
bit
TEC: Transmit Error Counter
REC: Receive Error Counter