The time-driven batch

Fill for 12.5 seconds with two pumps. Mix for 30. Shut everything off and wait for the next button press. That's a real batching skid, and the batch print runs it with five rungs and zero relays — just two timers and their status bits.

The whole program

    Stop        Start
──────[/]──┬─────[ ]─────┬──────[/T2.DN]──────( TON T1, 12.5 s )
           └───[T1.EN]───┘

──────[T1.TT]─────────────────( Pump P1 )
──────[T1.TT]─────────────────( Pump P2 )
──────[T1.DN]─────────────────( TON T2, 30 s )
──────[T2.TT]─────────────────( Mixer )

Walk it with the bits from the last lesson:

1. Start pressed. Rung 0 goes true and seals through T1.EN. T1 starts accumulating toward 12.5 s.
2. Filling. T1.TT is true, so both pumps run. The mixer waits — T1.DN is still false.
3. 12.5 s. T1 reaches its preset: TT drops (pumps stop by themselves), DN rises, and rung 3 starts T2. T2.TT turns the mixer on.
4. 42.5 s. T2 reaches 30 s: T2.DN goes true — and look back at rung 0: /T2.DN breaks the seal. T1 resets, which drops T1.DN, which kills T2, which clears T2.DN again. The whole machine falls back to rest in one cascade. One-shot, self-cleaning.

Why this is the pattern to steal

• The sequence lives in the timers, not in relays. Each stage is "what rides TT" and "what DN starts next." Adding a third stage is one timer and one rung, not a rewrite.
• The shutdown is wired into the start. /T2.DN on rung 0 means the batch cannot run past its recipe — the end of the sequence physically breaks the beginning. No "did we remember to stop it" bit.
• Stop is honest. The stop contact sits in series before everything. Press it mid-fill and T1 resets to zero — a new start refills from the top, never resumes half a batch. For a mix recipe, that's what you want.

What would break it

Swap the seal from T1.EN to a pump contact (M1) and the circuit dies at 12.5 s — the pumps stop, the seal drops, and T2 never runs. The seal must ride something that stays true for the whole batch. EN is that bit, because rung 0 itself stays true until /T2.DN says otherwise.

Run the real print

Load the batch in the builder — real presets from the print, 12.5 s and 30 s. Pulse Start once and watch the full batch: pumps, handoff, mixer, self-reset. Then press Stop mid-fill and confirm the accumulator goes back to zero.