PLC lab · Level 8 of 8
Duty and standby pumps
Level 8 of 8 in the PLC lab: a free PLC exercise at Intermediate level, which takes about 1 hour 15 minutes. Share the work between two pumps and take over within seconds when one trips.
Free · no download · about 1 hour 15 minutes. Your work is saved on this device. Updated 18 Oct 2026.
The brief
- Client
- Oakwood Towers
- Site
- Booster set BS-1
- Work order
- OT-2608
- Industry
- Building services
- Task code
- PLC-08
- Difficulty
- Intermediate
- Type of work
- Programming
Share the work between two pumps by alternating the duty pump on each demand, hand over to the standby when a pump trips, and flag when both have failed.
What you do
- Read the client brief and the tag table: 6 tags, 3 inputs and 3 outputs.
- Write the logic in ladder, Structured Text or SFC.
- Press Simulate and watch the plant answer your program.
- Run the factory acceptance test and fix what fails.
Skills you practise
- Duty/standby alternation
- Edge detection
- Fault takeover logic
- Pump protection
What the test checks
The factory acceptance test runs 5 numbered tests against your program. The numbers in the brief are drawn per learner. The tests are:
- Pump 1 takes the first demand, then the pumps take turns
- Pump 2 takes over when pump 1 trips
- Pump 1 takes over when pump 2 trips
- A tripped pump is never started
- Both pumps tripped lights Both failed
In this lab
- Ladder, Structured Text and SFC in one studio
- A plant that answers: motors, tanks, conveyors
- Numbered tests mark your program
Levels in the PLC lab
Part of the PLC lab
Program a working machine in ladder, Structured Text or SFC and watch it run.
Feeds these internships: PLC Programming.