Allen-Bradley Logix5000 Reference Manual page 446

Chapter 10 Sequencer Instructions (SQI, SQO, SQL)
Condition
Rung-condition-in is true.
No
.LEN ≤ 0 or
.POS < 0
Yes
No
.POS = .LEN
Yes
.DN bit is set.
Postscan
446
Relay Ladder Action
.EN = 0
examine .EN bit
.EN = 1
Error
.ER bit is set.
The rung-condition-out is set to false.
Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
.EN bit is set.
.ER bit is cleared.
.DN bit is set.
Yes
.POS ≥ .LEN
No
.POS = .POS + 1
Yes
.POS Value
Rolls Over
No
Yes
.POS = .LEN
.DN bit is set.
No
No
.POS > .LEN
Yes
.LEN > size of
Array[control.POS] = Source
Rung-condition-out is set
.POS = 1
Goto
Error
Yes
array
No
Major Fault
to true.
end