Lesson 8 — Delayed-On (TON)

Briefing

TON (Timer ON-delay) starts counting when its IN input is true. After the preset time PT elapses, the Q output goes true. If IN goes false before PT, the timer resets. Classic use: a warning lamp that turns on 3 seconds after a conveyor enable.

Objectives

• WARN_LAMP turns on 3 seconds after ENABLE goes true
• WARN_LAMP turns off immediately if ENABLE goes false before 3 s

I/O Table

Your program will be tested against:

All test cases run automatically when you submit. Assertions are hidden until you pass.

1. #1Lamp off during 3s delay

   ENABLE true, but lamp should still be off before 3 s elapses

2. #2Lamp on after 3.2 s

   After 3.2 s with ENABLE held, WARN_LAMP must be true

3. #3Timer resets when ENABLE goes false

   Remove ENABLE before 3 s, wait again — lamp stays off