PLC-Course

Lab 04 — Batch Mixer (SFC)

Sprint: 5 — Timers, Counters, Registers (with SFC concepts from Sprint 4) Time: ~2 hours

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🎯 Brief

Implement a 3-ingredient batch recipe:

1. Add 50 L of water (open Y_Water until Flow_Total ≥ 50)
2. Add 25 kg of sugar (open Y_Sugar until Weight_Total ≥ 25)
3. Run mixer for 30 seconds (Mixer_Run true, gated by Mix_Done)
4. Drain (open Y_Drain until Tank_Empty)
5. Return to idle

Implement as a phase machine in ST. The Hold_Timer_EN for the mixer is gated by the phase.

I/O

Tag	Type	Description
Start / Stop / EStop	BOOL	Standard controls
Flow_Total	INT	Cumulative water (L)
Weight_Total	INT	Cumulative sugar (kg)
Mix_Done	BOOL	Mixer timer elapsed
Tank_Empty	BOOL	Drain complete sensor
Y_Water / Y_Sugar / Y_Drain	BOOL	Valves
Mixer_Run	BOOL	Mixer contactor
Phase	INT	0=Idle, 1=Water, 2=Sugar, 3=Mix, 4=Drain

Test cases

See tests/cases.json. Submit as solution.st.

Hint

Look at Lab 03 for the phase-machine pattern. This is the same pattern with more steps.

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