Rockwell Automation AutoMax Enhanced Ladder Language Reference Manual - Manual (Page 31)

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1.9 Set (Latch) Coil (SCO)
Use this output instruction to set the Boolean variable on (1) when the input condition is
true.
The SCO instruction is an instruction that can only turn on a bit (it cannot turn off a bit).
This instruction is usually paired with an RCO (reset unlatch) instruction, with both
instructions addressing the same bit.
When enabled, the latch instruction turns on the addressed bit. After this, the bit
remains on (regardless of the rung condition) until the bit is turned off, typically by an
RCO instruction in another rung.
If the rung is: Then the instruction turns the bit:
true on
false no change
The supported variables are:
D simple Boolean
D Boolean array element
D bitĆindexed integer or double integer
D bitĆindexed integer or double integer array element
Example of a Set (Latch) Coil (SCO)
This rung shows that when switch1 is on, the
variable tank_fill is on until it is reset by an RCO
instruction.