Allen-Bradley Logix5000 Reference Manual page 420

Chapter 9 Array (File)/Shift Instructions (BSL, BSR, FFL, FFU, LFL, LFU)
Condition
Rung-condition-in is true.
Examine .EU bit.
.EU = 1
Yes
.LEN < 0
No
Yes
.POS < 0
No
.EM bit is cleared.
.DN is cleared.
Yes
.POS = 0
No
Yes
≥
.POS .LEN
No
Rung-condition-out is set
to true.
Postscan
420
Relay Ladder Action
.EU = 0
.EU bit is set.
.EM bit is set.
.DN is set.
.EM bit is set.
.DN bit is set.
End
The rung-condition-out is set to false.
Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
Yes
.LEN < 0
No
Yes
.POS < 0
No
.EM bit is cleared.
.DN is cleared.
Yes
.LEN > Size
Major Fault
Of Array
No
Yes
≤
.POS 1 .EM bit is set.
No
Yes
Destination = 0
.POS < 1
No
.POS = .POS -1
Destination = FIFO[0]
i = 1
FIFO[i - 1] = FIFO[i]
i = i +1
Yes
i < .LEN
No
.EM bit is set.
.DN is set.