Allen-Bradley ProcessLogix B Series

ProcessLogix and ControlLogix System Redundancy Module 21
Publication
1757-IN092E-EN-P - November 2007
Flowchart of Starting a Chassis with a Healthy 1757-SRM Module
1757-SRM module
is started
Lock backplane to stall
faster starting modules
Perform Self-Test.
display:Txxx
Pass Self Test?
Assert SYS_FAIL
Yes
The 1757-SRM module waits up to five seconds
for a more slowly starting 1757-SRM module.
Is another
1757-SRM module
present?
Other 1757-SRM module
out of Powerup or in a
lower slot
Release backplane lock
No
Release backplane lock
Begin search for
other module
Major Unrecoverable
Fault State
display:Exxx
1757-SRM module reports faults
and status via Health Status,
four-character display, and/or
backplane.
1757-SRM module
deactivates User Relay upon
entering a major fault state.
Ten-second
startup
search period
No
Module
found?
Redundancy
compliant?
Notify module of
1757-SRM presence
Yes
No
No
Yes
After the release of the backplane lock, the 1757-SRM module
has 200 ms to notify any waiting modules.
Alone (no partner
chassis)?
Partner also
during start?
Partner
already
primary?
No
No
No Partner Chassis
display:PRIM
Partner also in
Powerup display:????
Partner is Primary
display:DISQ
Partner is disqualified
secondary display:PRIM
Yes
No
No
No
YesYes
Yes
Yes
No
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