3

Frequency Error

Allen-Bradley · MicroLogix 1400 Programmable Controllers

What does 3 mean?

The operating frequency value (OFS) specified for the PTOX instruction is less than 0 or greater than 100,000 pulses per second. This error faults the controller and indicates an invalid frequency parameter. It can be cleared by logic within the User Fault Routine.

Common Causes

  • Operating frequency (OFS) parameter set to an out-of-range value (i.e., less than 0 or greater than 100,000).
  • Incorrect calculation or direct input of an invalid frequency parameter in the PTOX instruction.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Adjust the operating frequency (OFS) value in the PTOX instruction to be within the valid range of 0 to 100,000.

  2. 2

    Review the program logic that writes to the OFS parameter to ensure it calculates and sets a valid frequency.

  3. 3

    Clear the fault using the User Fault Routine or by cycling power after correcting the OFS value.

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Verified technical data. Last updated: March 2026

Related Faults

Source: Allen-Bradley MicroLogix 1400 Programmable Controllers