Been using this trick for ages...
Valve_ZSC + Valve_ZSO*2
0 closed=0, open=0 - valve is moving (if it persists too long, it's a fault)
1 closed=1, open=0 - valve is closed
2 closed=0, open=1 - valve is open
3 closed=1, open=1 - limit switch failure (one or the other is stuck)