PLC-Course

Lab 03 — Tank Fill/Drain with Level Control

Sprint: 5 — Timers, Counters, Registers Languages allowed: ST or LD Time: ~2 hours

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🎯 Brief

A water tank has a level transducer (4–20 mA → 0–100% scaled value). When the operator presses START, the system runs an automatic fill-then-drain cycle:

1. Open inlet valve until level ≥ 80%
2. Close inlet, hold for 5 seconds
3. Open outlet valve until level ≤ 10%
4. Close outlet, return to idle

The system must abort safely on STOP or EStop.

📋 I/O List

Tag	Type	Description
Start	BOOL	Start cycle
Stop	BOOL	Stop cycle
EStop	BOOL	E-stop (NC, true when OK)
Level_Pct	INT	Level 0–100 % (scaled from 4–20 mA)
Hold_Done	BOOL	True when hold timer has elapsed
Inlet_Valve	BOOL	Inlet solenoid
Outlet_Valve	BOOL	Outlet solenoid
Hold_Timer_EN	BOOL	Enable for the hold timer
Phase	INT	0=Idle, 1=Filling, 2=Holding, 3=Draining
Cycle_Active	BOOL	True between Start and end of Drain

🚦 Phase Transitions

• 0 → 1: Start AND EStop AND NOT Stop
• 1 → 2: Level_Pct ≥ 80
• 2 → 3: Hold_Done
• 3 → 0: Level_Pct ≤ 10
• Any → 0: Stop OR NOT EStop

The Hold_Timer_EN should be true only during Phase 2.

Submit solution.st.

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