Rockwell Automation 1775-S5_SR5,D17756.5.5 User Manual PLC-3 FAMILY I/0 - Manual (Page 121)

Diagnostics Methods
Chapter 7
7-9
Upon executing a retry, if the I/O adapter responds properly, normal
operation continues. If the I/O adapter does not respond properly, the
scanner continues to execute retries until:
the I/O adapter returns a valid response, or
the processor declares a major or minor I/O fault based on how you
configure the rack list in LIST.
Adapters on channel: Number of consecutive retries that execute
before the processor declares an I/O fault:
1 10
2 8
3 to 7 6
8 to 16 4
If the processor declares an I/O fault, it sets the following bits:
I/O adapter fault status bit file 2 that corresponds to the I/O adapter
major or minor I/O fault bit in system status
The scanner continues scanning the I/O chassis. When it returns to the
faulted I/O adapter, it attempts to reset the input or output and moves on to
the next I/O adapter.
Important: Upon declaring a major or minor I/O fault, if normal
communication returns to the I/O adapter, the processor does not reset the
I/O adapter fault bit in status file 2 or the major I/O or minor I/O fault bit
in system status.
If you do not want normal communication to return to a faulted I/O
adapter, set the processor-reset-lockout switch on the I/O chassis. With
this switch set, the I/O adapter does not reply to the scanner once a fault is
declared until you cycle power at the I/O chassis or press the reset button
on the I/O adapter.
If you configure an I/O channel for peer-to-peer or backup communication,
and communication problems occur between two scanners (master, slave,
primary, or backup) on the channel, a retry executes. If the communication
occurs properly, normal operation continues.
If communication problem continues to occur, the scanners:
set the peer-to-peer or backup communication minor fault status bit in
system status
flash the LED corresponding to the channel on their front edges
Retries for a PeerĆtoĆPeer or
Backup Communication
Channel