Allen-Bradley Logix5000 Reference Manual page 442

Chapter 10 Sequencer Instructions (SQI, SQO, SQL)
Condition
Prescan
Rung-condition-in is false
Rung-condition-in is true.
No
.LEN ≤ 0 or
.POS < 0
Yes
No
.POS = .LEN
Yes
.DN bit is set.
Postscan
442
Execution:
Relay Ladder Action
The .EN bit is set to prevent a false load when the program scan begins.
The rung-condition-out is set to false.
The .EN bit is cleared.
The rung-condition-out is set to false.
.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
Goto
.POS Value
Error
rolls over
No
Yes
.POS = .LEN .DN bit is set.
No
No
.POS > .LEN
Yes
Destination = (Destination AND (NOT(Mask)))
OR (Array[control.POS] AND Mask)
Rung-condition-out is
set to true.
.POS = 1