I think you may be misinterpreting how the invert parameter operates,
it does not change the state of the parport.0.pin-NN-out hal pin.
(It cannot as this hal pin would be driven by a hal signal)
but rather changes the physical output polarity. You cannot
detect this change in the parport.0.pin-NN-out hal pin but only by
measuring the actual parallel port hardware output pin.
