Rockwell Automation 1775-S4B,D17756.5.3 User Manual SCANNER/MSG HND - Manual (Page 37)

Operating the LIST Function
Chapter 4
4Ć15
If this situation occurs you should:
Clear the bad fault address in a fault routine
Clear the block transfer bit
Restart the block transfer in the ladder diagram program
Auto config first creates a new I/O chassis list in which each I/O chassis
has equal priority with no attributes assigned. Then a reconfiguration
executes.
The 1775-S4B scanner performs an auto configure at powerup under the
following conditions:
No I/O channel configured for I/O scan has entries in the rack list.
Neither auto configure nor reconfigure has been selected during a
previous powerup (at least since the last time you cleared memory).
When forming the I/O chassis list during an auto configuration, the
1775-S4B scanner polls all valid addresses (rack 0 to 768). If the
1775-S4B scanner receives response to an address, it adds that I/O rack
address to the list. To assign attributes or priorities to the I/O chassis, add
them manually through LIST and reconfigure the I/O channel.
You can only perform an auto configuration when:
PLC-3 processor is in program load mode.
Power is applied to the I/O chassis.
Switch 2 of each I/O chassis is set to “on” to allow the I/O chassis to be
restarted from the PLC-3 processor.
If power is not applied to the I/O chassis, the PLC-3 processor attempts to
perform an auto configuration, and since the I/O chassis does not respond,
the 1775-S4B scanner does not enter it in the I/O chassis list. For an entry
to get into the I/O chassis list in auto config, a valid communication path
must exist between the 1775-S4B scanner and the I/O adapter module for
the I/O chassis.