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Mission 18 · Pro valve feedback exercise

A command is not feedback

Check that the valve really opened.

Open the valve with ValveCmd while Start is held and Permit is ON. ValveOpen is feedback: a switch on the valve that confirms it really opened. If ValveCmd is ON but ValveOpen stays OFF for 200 ms, turn Alarm ON. When the valve opens or the command ends, clear the and Alarm.

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The 3D process tank this mission runs on Pro mission
Test replay

No Alarm when the valve opens in time

Test 1 of 5
Set by the testChecked by the testStep 2 of 2 · 500 ms
Level
Applied
Time
About 12 min
Reward
+200 XP
Rig
3D process tank
Siemens editors
FBD
Rockwell editors
FBD
Course stage
8. Ask for evidence
Automatic tests

What the tests check

  1. Holding Start with Permit ON turns ValveCmd ON.
  2. No Alarm while the valve has its 200 ms to open.
  3. If ValveOpen is still OFF after 200 ms, Alarm turns ON.
  4. When ValveOpen turns ON, the timer and Alarm clear.
  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 drinks mixer tells its ingredient valve to open. A switch on the valve reports whether it really opened.

A stuck valve can leave an ingredient out of the batch. Allowing time for the valve to move avoids an alarm every time it opens normally.

Where you'd find thisMaking one batch of drink

At a drinks factory, valves let measured amounts of water and syrup into a mixing tank. An electric mixer blends them into one batch. An outlet valve then sends the drink to a holding tank. Filling machines bottle it from there.

  1. Ingredient tanksHold the water and syrup
  2. Mixing tankFill, mix and measure one batchYou are here
  3. Holding tankKeeps the finished drink ready
  4. Bottle fillerPuts the drink into bottles
On a real site: places, parts and safety
  • Drinks factory — blending water and syrup
  • Paint factory — mixing ingredients into a consistent colour
  • Water-treatment works — preparing a measured chemical mixture
  • Brewery — heating water for washing equipment

A full tank does not close its own inlet. Water keeps arriving until the valve closes, so an open inlet can flood the room.

A heater that is not covered by liquid can overheat. Real tanks have separate safety devices as well as the PLC programme.

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

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