What PLC Timers Are Used in Studio 5000 Logix Designer

RealPars
RealParsMar 9, 2026

Why It Matters

Choosing the right timer instruction directly affects process reliability and maintenance scheduling, giving engineers a powerful tool to optimize automation performance.

Key Takeaways

  • TON delays signal activation until preset time elapses.
  • TOF delays signal deactivation, opposite of TON behavior.
  • RTO retains accumulated time across power cycles for total tracking.
  • Non‑retentive timers reset ACC when disabled, losing elapsed time.
  • Studio 5000 offers additional timer types in other programming languages.

Summary

The video introduces PLC timers and walks through the specific timer instructions available in the Ladder Diagram environment of Studio 5000 Logix Designer. It explains why timers are essential for delaying signal transitions and sets the stage by describing the generic Delay‑On timer behavior.

Three core instructions are covered: TON (Timer On Delay) for delaying turn‑on events, TOF (Timer Off Delay) for delaying turn‑off events, and RTO (Retentive Timer On) which preserves accumulated time when disabled. The presenter details each instruction’s ACC (accumulated), PRE (preset), and Done bits, and notes that TON and TOF are non‑retentive while RTO requires a RES (reset) instruction to clear its count.

A practical example highlights using an RTO to log total motor run time and trigger scheduled maintenance, illustrating how retentive timers support long‑term tracking. The video also points viewers to the Learn Logix 07 course for deeper hands‑on practice and mentions that other programming languages in Studio 5000 (e.g., Function Block Diagram) provide additional timer variants.

Understanding these timer types enables automation engineers to select the correct instruction for precise control, reduce downtime, and streamline maintenance planning—critical factors for efficient industrial operations.

Original Description

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▶ You can read the full article here:
⌚Timestamps:
00:00 - Intro
00:22 - Timer concepts
01:53 -Timer On Delay (TON)
03:23 - Timer Off Delay (TOF)
04:02 - Retentive Timer On (RTO)
05:25 -Wrap-Up
Timers are very important instructions in PLC programming that are used to delay signals from turning on or off.
This video explains the concept of timers in PLC programming and explains the specific timer instructions available for the Ladder Diagram programming language in Studio 5000 Logix Designer.
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Check out the course mentioned in the video:
Learn Logix 7: Programming Timers and Counters
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