Rockwell Automation Publication 1756-RM003N-EN-P - October 2011 403
Array (File)/Shift Instructions (BSL, BSR, FFL, FFU, LFL, LFU) Chapter 9
Description: When enabled, the instruction unloads the uppermost bit of the specified bits to
the .UL bit, shifts the remaining bits one position left, and loads Source bit into
bit 0 of Array.
Arithmetic Status Flags: Not affected
Fault Conditions:
Execution:
You must test and confirm that the instruction doesn’t
change data that you don’t want it to change.
The BSL 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.
A major fault will occur if Fault type Fault code
Length exceeds the size of Array's storage
area.
420
Condition Relay Ladder Action
Prescan 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.
Rung-condition-in is 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.
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