Rockwell Automation AutoMax Enhanced Ladder Language Reference Manual - Manual (Page 32)

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1.10 Reset (Unlatch) Coil (RCO)
Use this output instruction to reset a Boolean variable to off (0) when the input
condition is true.
The RCO instruction is a retentive output instruction that can only turn off a bit (it cannot
turn on a bit). This instruction is usually paired with an SCO (set latch) instruction, with
both instructions addressing the same bit.
When enabled, the unlatch instruction turns off the addressed bit. After this, the bit
remains off (regardless of the rung condition) until it is turned on, typically by an SCO
instruction in another rung.
If the rung is: Then the instruction turns the bit:
true off
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
Example of a Reset (Unlatch) Coil (RCO)
This rung shows that when switch2 is on the
variable tank_fill will be off until it is set by an
SCO instruction.