📢 Fresh Content: PLC Troubleshooting Tips That Work Across Any Platform | Click to read on PLCBlog!
AdvancedFive Rung / Mission~25 min
Five Rung (Mission)
The pattern real machines are built from: command a motion, seal it in while it runs, latch Done when the sensor confirms it, and latch a Fault if a watchdog timer expires first. One structure safe moves, detected failures.
Your goal
- A Go pulse starts the move: Advance ON, sealed in.
- When AtWork confirms position, the move ends (Advance OFF) with no fault.
- If AtWork does NOT arrive within 2 s, Fault latches and Advance stops.
- Reset clears the fault. A new Go pulse must be able to run the mission again.
Stuck? Show hints (4)
- R1 (the seal): (NO Go OR NO Advance) AND NC Done AND NC Fault → OTE Advance.
- R2 (watchdog): NO Advance → TON Twd. It only times while the motion is commanded.
- R3: NO Advance AND NO AtWork → OTL Done. R4 (re-arm): NC Go AND NC Advance → OTU Done.
- R5: NO Twd.DN → OTL Fault. R6: NO Reset → OTU Fault. Fault breaks R1's seal, which also stops the watchdog.
Pattern from Contact & Coil's classic ladder logic series.
I/O for this exercise
| Inputs | |
| Go | Start mission button |
| AtWork | End-position sensor |
| Reset | Fault reset button |
| Outputs | |
| Advance | Advance valve / motion output |
| Fault | Mission fault lamp |
| Internal coils | |
| Done | Mission complete flag |
| Timers | |
| Twd · 2000ms | Motion watchdog |
Loading the editor…