Conditions

For an introduction to the DSL vocabulary, see Core Concepts.

Everything that goes inside Rung(...). All forms can be mixed freely.

Fault                          tag is truthy
~Fault                         tag is falsy
MotorTemp > 100                comparison  (==  !=  <  <=  >  >=)
Fault, Pump                    comma = implicit AND
Fault, MotorTemp > 100         implicit AND with comparison
And(Fault, Pump, Valve)        explicit AND (same as commas)
Or(Low, High, Emergency)       explicit OR
Or(Start, And(Auto, Ready))    nested AND inside OR

Normally open (examine-on)

with Rung(Button):          # True when Button is True
    out(Light)

Normally closed (examine-off)

with Rung(~Button):      # True when Button is False
    out(FaultLight)

Rising and falling edge

with Rung(rise(Button)):    # True for ONE scan on False→True transition
    latch(Motor)

with Rung(fall(Button)):    # True for ONE scan on True→False transition
    reset(Motor)

Multiple conditions (AND)

# Comma syntax — all must be True
with Rung(Button, ~Fault, AutoMode):
    out(Motor)

# And() — explicit AND
with Rung(And(Button, ~Fault, AutoMode)):
    out(Motor)

OR conditions

# Or() — at least one must be True
with Rung(Or(Start, RemoteStart)):
    latch(Motor)

Nested AND/OR

with Rung(Or(Start, And(AutoMode, Ready), RemoteStart)):
    latch(Motor)

Comparisons

with Rung(Step == 0):
    out(InitDone)

with Rung(Temperature >= 100.0):
    latch(OverTempFault)

with Rung(Counter != 5):
    out(NotAtTarget)

INT truthiness

INT tags are True when non-zero:

with Rung(Step):                    # True if Step != 0
    out(StepActive)

with Rung(Or(Step, AlarmCode)):
    out(AnyActive)

Inline expressions

with Rung((PressureA + PressureB) > 100):
    latch(HighPressureFault)

Inline expressions work in simulation. The Click dialect validator will flag them if targeting Click hardware — rewrite as calc() instructions instead.