AcroPack Series AP560
CAN Bus Interface Module
- 35 -
Overload Frame
The overload frame is shown in Figure 6. It has the same format as the active
error frame, consisting of an overload flag field and an overload delimiter. The
overload flag consists of 6 consecutive dominant bits. This condition violates
the rule of bit-stuffing and causes all other nodes on the bus to generate echo
flags, similar to the active error flag echoes. Therefore, the overload flag field
will consist of the superposition of different overload flags sent by individual
nodes, resulting in a minimum of 6 and maximum of 12 consecutive dominant
bits. The overload flag is followed by the overload delimiter, consisting of 8
recessive bits.
An overload frame, unlike an error frame, can only be generated during the
interframe space. There are two types of overload frames:
1.
Reactive Overload Frame
, resulting from
a.
detection of a dominant bit during the first or second bit of
intermission
b.
detection of a dominant bit at the last (seventh) bit of EOF in
received frames, or
c.
detection of a dominant bit at the last (eighth) bit of an
error delimiter or overload delimiter.
The reactive overload frame is started one bit after detecting
any of the above dominant bit conditions.
2.
Requested Overload Frame.
A node which is unable to begin
reception of the next message due to internal conditions may request
a delay by transmitting a maximum of two consecutive overload
frames. The requested overload frame must be started at the first bit
of an expected intermission.
Note 1):
The HI-3111 will never initiate an overload frame unless
reacting to one of the conditions in case 1) above.
Note 2):
Initiation of overload frames is prohibited by ARINC 825
since they increase the network loading.
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...
