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
Scan the PTOX instruction on a false rung to acknowledge the error condition.
- 2
Reset the EH (Enable Hard Stop) bit to 0 in the PTOX configuration to clear the error.
- 3
Inspect the physical hard stop sensor and its wiring to ensure it is not falsely triggering or stuck in an activated state.
Verified technical data. Last updated: March 2026
Related Faults
Source: Allen-Bradley MicroLogix 1400 Programmable Controllers