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Mission 72 · Pro PLC programming exercise

Alarms in priority order

New alarms flash and sound until acknowledged; the urgent one comes first.

Make the lift station's alarms tell the operator what to do first: sorted by priority, flashing only until acknowledged, with a horn for the urgent ones. Write the side of acknowledgement.

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The 3D pumping station control this mission runs on Pro mission
Test replay

Ack silences, the alarm stays

Test 1 of 4
Set by the testChecked by the testStep 6 of 6 · 660 ms
Level
Advanced
Time
About 30 min
Reward
+350 XP
Rig
3D pumping station control
Siemens editors
Ladder (LAD), SCL
Rockwell editors
Ladder, Structured Text
Beckhoff editors
Structured Text
Course stage
38. Operator screens 3: alarms in priority order
Automatic tests

What the tests check

  1. The alarm list puts the most urgent alarm at the top.
  2. Priority shows by shape and number as well as colour; only unacknowledged alarms flash.
  3. A new alarm sets its unacknowledged flag; Ack clears it, on the press only.
  4. An alarm that clears before anyone acknowledges it keeps showing until Ack.
  5. Horn sounds for unacknowledged priority 1 and 2 alarms, never for priority 3.
  6. TopPriority is 1, 2 or 3 for the most urgent alarm still showing, or 0.
  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

Sewage lift stations are unmanned. Their alarms go to a control room that watches dozens of stations at once, at night often with one person on duty.

When a storm trips pumps across a town, a list sorted by time hides the one station about to flood under a pile of minor alarms.

Where you'd find thisNever flood, never run dry, never wear out one pump

Sewage and storm water stations run unattended for years. The controller stages pumps on the level, spaces their starts so the supply is not overloaded, shares the running hours, and falls back to simple floats if the level sensor fails.

  1. SewerInflow
  2. Wet wellUltrasonic + floatsYou are here
  3. Pumps1, 2 or 3
  4. Rising mainTo the works
On a real site: places, parts and safety
  • Sewage and surface water pumping stations
  • Mine and quarry dewatering
  • Building basements and road underpasses

Wet wells are confined spaces with hydrogen sulphide: nobody goes in without a permit, gas monitor and rescue plan.

A flooding station pollutes rivers and homes, and is reported to the regulator.

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

Keep going

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