Watchdog Timers Improve Safety and Reliability of Critical PLC-Controlled Systems

A Watchdog Timer can be added to PLC- or computer-controlled systems to improve safety and reliability. The separate, independent timer is triggered at regular intervals by the control system.

When operating normally, the PLC continuously retriggers the timer. If a fault occurs in the logic hardware or software, the timer is not retriggered within the expected interval. The timer’s output can shut down critical systems or alert an operator before safety concerns arise.

An example of a widely used Watchdog Timer for PLC is Regent Controls’ TM2222. This product can be used as a Motion Control Timer or a One-Shot Timer by a simple switch setting. In either setting, the TM2222 can be triggered by a proximity sensor, limit switch, photoelectric control, PLC output module, etc. using sinking or sourcing switching.

Additional benefits of the TM2222 watchdog timer include:

  • Timer is independent of the PLC or computer. Hardware based. No software to program.
  • Timer can be adjusted for any cycle rate or scan time. Fixed timing is also available.
  • Models available for 120VAC and 24VDC control systems.
  • Compact size, DIN rail or panel mount
  • LED load and logic indicators
  • Compatible with PLCs, sensors, solenoids, contactors, and more
watchdog timer

For more information about watchdog timers to help improve PLC system safety, contact our experts. Simply fill out the brief form on this page, call 860-732-6200 or email and a member of our team will be in touch soon.

We also welcome your CAD, diagrams, and schematics. Click the blue button on the right to upload your specifications and a Regent Controls engineer will contact you. We look forward to learning more about your industrial control needs and how we can provide a solution tailored to your requirements.

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