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ErrorLib — Industrial Fault Code Library

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1

Hardstop Detected

Allen-Bradley · MicroLogix 1400 Programmable Controllers

What does 1 mean?

This error is generated whenever a hard stop condition is detected by the PTOX subsystem, indicating that a physical limit or emergency stop input has been activated. This error does not fault the controller.

Common Causes

  • Physical limit switch activation on the controlled axis.
  • External condition triggering a hard stop input to the PTOX subsystem.
  • Incorrect configuration of hard stop monitoring causing false triggers.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Scan the PTOX instruction on a false rung to acknowledge the error condition.

  2. 2

    Reset the EH (Enable Hard Stop) bit to 0 in the PTOX configuration to clear the error.

  3. 3

    Inspect the physical hard stop sensor and its wiring to ensure it is not falsely triggering or stuck in an activated state.

Browse all codes in this manual (60)
Verified technical data. Last updated: April 2026

Related Faults

-1Output Error-2Overlap Error-3Undefined Accel/Decel
Source: Allen-Bradley MicroLogix 1400 Programmable Controllers
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