BeginnerSealed in Coil~10 min

Sealed-in Coil

A fill valve that opens on a button press and holds itself open until the tank-full sensor stops it. The seal-in coil is the building block behind almost every 'stays running until done' behavior.

Your goal

  • Pressing FillBtn opens the FillValve.
  • Releasing FillBtn keeps the valve open (sealed in).
  • When TankFull turns ON, the valve closes and stays closed until FillBtn is pressed again.
Stuck? Show hints (2)
  1. Same shape as Start/Stop the 'stop' here is the process itself: a NC contact of TankFull.
  2. Branch row: NO contact of FillValve in parallel with FillBtn, vertical link after that column.

Pattern from Contact & Coil's classic ladder logic series.

I/O for this exercise

Inputs
FillBtnFill push button
TankFullTank full level sensor
Outputs
FillValveFill valve solenoid
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