Allen-Bradley Logix5000 Reference Manual page 407

Description:
Arithmetic Status Flags:
Fault Conditions:
Execution:
Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
Array (File)/Shift Instructions (BSL, BSR, FFL, FFU, LFL, LFU)
When enabled, the instruction unloads the value at bit 0 of Array to the .UL bit,
shifts the remaining bits one position right, and loads Source bit into the
uppermost bit of the specified bits.
IMPORTANT
Not affected
A major fault will occur if
Length exceeds the size of Array's storage
area.
Condition
Prescan
Rung-condition-in is false
You must test and confirm that the instruction doesn't
change data that you don't want it to change.
The BSR instruction operates on contiguous memory. If an
Array is a member array, such as contained within a
structure, it is possible that the instruction could shift
beyond the Array's boundary into other members following
it. You must take care in choosing a length whereby this
does not happen.
Fault type
4
Relay Ladder Action
The .EN bit is cleared.
The .DN bit is cleared.
The .ER bit is cleared.
The .POS value is cleared.
The rung-condition-out is set to false.
The .EN bit is cleared.
The .DN bit is cleared.
The .ER bit is cleared.
The .POS value is cleared.
The rung-condition-out is set to false.
Chapter 9
Fault code
20
407