IntermediateFlasher~15 min

Flasher

Two timers chained in a loop make a lamp blink: the classic two-TON flasher used for warning beacons everywhere. Your first taste of timers driving each other.

New here? How to use it

Your goal

  • While Enable is ON, the Lamp blinks: ON for 1 s, OFF for 1 s, repeating.
  • When Enable is OFF, the Lamp is OFF and both timers are reset.
Stuck? Show hints (3)
  1. Rung 1: NO Enable AND NC T2.DN → TON T1. Rung 2: NO T1.DN → TON T2.
  2. T1 times up, which starts T2; when T2 finishes, its DN bit breaks rung 1, resetting T1 which resets T2, and the cycle repeats.
  3. For the lamp: T1.TT is TRUE only while T1 is actively timing. Rung 3: NO T1.TT → OTE Lamp.

Pattern from Contact & Coil's classic ladder logic series.

I/O for this exercise4 tags · show
Inputs
EnableFlasher enable switch
Outputs
LampBeacon lamp
Timers
T1 · 1000msPhase 1 timer
T2 · 1000msPhase 2 timer
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