Allen-Bradley Logix5000 Reference Manual page 430

Chapter 9 Array (File)/Shift Instructions (BSL, BSR, FFL, FFU, LFL, LFU)
Condition
Prescan
.EU bit is set to prevent a false
unload when scan begins.
.LEN < 0
No
.POS < 0
No
.EM is cleared.
.DN is cleared
.POS = 0
No
≥
.POS .LEN
no
rung-condition-out is set to
false.
End
430
Execution:
Relay Ladder Action
Yes
Yes
Yes
.EM is set.
Yes
.DN is set.
Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
.EM is set
.DN is set