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Mission 73 · Pro PLC programming exercise

Ask before you can't undo

Confirm only what can't be taken back, and say what will happen.

Make Abort on the reactor's screen ask first, in a question nobody can misread, while Hold and Restart still act at once. Write the 's side of the question: open it, wait 10 s for an answer, and abort only on a fresh Confirm.

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The 3D batch reactor control this mission runs on Pro mission
Test replay

Abort asks, then acts on Confirm

Test 1 of 5
Set by the testChecked by the testStep 6 of 6 · 760 ms
Level
Advanced
Time
About 30 min
Reward
+350 XP
Rig
3D batch reactor control
Siemens editors
Ladder (LAD), SCL
Rockwell editors
Ladder, Structured Text
Beckhoff editors
Structured Text
Course stage
39. Operator screens 4: ask before you can't undo
Automatic tests

What the tests check

  1. Only Abort asks before acting; Hold and Restart act at once.
  2. The question says what will be lost, with buttons that say what they do, away from where Abort was.
  3. AbortRequest while Running or Held opens the question: ConfirmPending ON, batch untouched.
  4. A fresh Confirm within 10 s aborts the batch: AbortLamp ON, ConfirmPending OFF.
  5. Cancel, or 10 s with no answer, closes the question and the batch carries on.
  6. Confirm with no question open, or held from before, does nothing.
  1. Try it Use the buttons below the model and watch the rig respond.
  2. Test solution Every check runs on your code in one press.
  3. Replay If one fails, step through it one scan at a time to see why.
Why it matters

Where you’d see this on site

A batch reactor making a speciality chemical holds a day's production worth thousands. Its operator screen sits on a touch panel by the vessel, used with gloves on.

One accidental tap on an Abort that acts at once sends a whole batch to waste, and it can't be undone.

Where you'd find thisMake the batch, keep the reaction in hand, and stop safely at any moment

Chemical, pharma and food batch plants follow recipes in phases. Operators can hold a batch and restart it, or abort it; the controller must know exactly what is safe in every state. Some reactions release heat, and if cooling falls behind they run away.

  1. ChargeA, then B
  2. React80 °C for 30 sYou are here
  3. CoolTo 40 °C
  4. DischargeTo receiver
On a real site: places, parts and safety
  • Speciality chemicals and resins
  • Pharmaceutical and biotech batch suites
  • Food ingredients and flavours

Runaway reactions caused disasters such as Seveso (1976) and T2 Laboratories (2007). Real reactors have independent high-temperature trips and relief systems.

ISA-88 defines the state model used here, so operators everywhere know what Hold and Abort mean.

The sizes, timings and cutaways are teaching choices, not a drawing of any one real installation.

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