What the E.31 alarm means

The following error between commanded and actual axis position exceeded the allowed limit during motion; the controller stops the program to protect the mechanics. We fix this ESTUN ERC / ED3L controller + ESTUN servo fault almost daily, and one round of on-site checks usually confirms what is going on.

Most common causes

  • Obstruction or collision in the axis path
  • Load above rating or brake dragging
  • Servo gain too low for the duty
  • Encoder feedback noisy or intermittent
Field note: We have tallied real cases: the first cause tops the list, so start your diagnosis there.

Step-by-step field fix

  1. Clear any obstruction and inspect for collision damage
  2. Verify payload settings and brake release
  3. Re-tune or restore default servo gains for the axis
  4. Check encoder cable condition through the cable track
  5. Re-run at reduced speed to confirm the axis tracks cleanly
Safety first: For ESTUN e-31, this alarm family points at arm motion control: after a reset the arm can move unexpectedly, and anyone inside the working envelope is at strike and pinch risk. What you can check yourself first is Clear any obstruction and inspect for collision damage; the arm working envelope handling is not a DIY job.

How we diagnose motion alarms on site

ESTUN e-31 belongs to the motion & path family. On ESTUN e-31 the failing stage is matched servo drives (in-house / Inovance-class servos) on the ESTUN robot controllers (motion-control-platform based) - the gap between command and execution: trajectory planning, joint limits, singularities, following error and mechanical resistance. We start reading ESTUN e-31 at the pendant alarm list (A.xxx / E.xxx segments) and the servo panel display code.

The chain involved in ESTUN e-31 runs: program command -> trajectory planner -> joint targets -> servo execution -> actual position feedback -> deviation compare.

If Obstruction or collision in the axis path on ESTUN e-31 comes with a feeling of drag, the direction is clear: Following error that stays high on one axis only is usually rising mechanical resistance, not a weak servo. We turn the axis by hand with the brake released to feel smoothness, and listen to the reducer for once-per-revolution knocking - a single tick per turn on an RV reducer usually means internal bearing or cycloid damage. Grease that is black, dry or carries metal powder is the plainest evidence. Left alone, this graduates from a motion alarm to a scrapped reducer.

Field notes on this page cover ESTUN e-31 (Position Deviation Over Limit); written by the Henghuan repair team, updated 2026-10-01.

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Related Motion & Path alarms

A.51 — Overspeed
Same family: this code belongs to the Motion & path alarms family - the page collects all Motion & path-family codes we have handled, with the common inspection order and spares.
Other brands: we also keep field-fix libraries for INOVANCE · EFORT · JAKA and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the ESTUN e-31 alarm mean?

The following error between commanded and actual axis position exceeded the allowed limit during motion; the controller stops the program to protect the mechanics. We fix this ESTUN ERC / ED3L controller + ESTUN servo fault almost daily, and one round of on-site checks usually confirms what is going on. ESTUN e-31 sits in the motion & path family; on our work orders the highest-frequency trigger for this code is "Obstruction or collision in the axis path".

QCan I clear a ESTUN e-31 alarm myself?

Whether ESTUN e-31 clears on its own depends on the outcome of "Clear any obstruction and inspect for collision damage". Finish the flow with "Re-run at reduced speed to confirm the axis tracks cleanly" to confirm ESTUN e-31 - do not skip it. If that step is clean, the second most frequent cause on ESTUN e-31 is "Load above rating or brake dragging". Two attempts and still there means stop: ESTUN e-31 involves the arm working envelope, and running ESTUN e-31 on can turn a repairable fault into a replacement.

QFor motion alarms like ESTUN e-31, can you triage remotely first?

The commonest causes we see on ESTUN e-31 are "Obstruction or collision in the axis path, Load above rating or brake dragging, Servo gain too low for the duty", so we stock the van against those. For ESTUN e-31 specifically, we carry mechanical and configuration items: grease, limit switches, drag-chain segments, encoder cables and the parameter sheets for common reducers. For ESTUN e-31, motion alarms can often be narrowed remotely first, so an on-site visit is not always immediate. Before we roll, tell us what ESTUN e-31 shows on the pendant alarm list (A.xxx / E.xxx segments) and the servo panel display code and what the machine was doing - phone or video triage is free.

This page on ESTUN e-31 was compiled from actual repair records of the Henghuan Robotics repair team. Alarm notes are our own summary for troubleshooting reference only and may vary with controller and software version — please consult ESTUN documentation or contact us if in doubt. Henghuan is an independent service provider, not affiliated with or endorsed by ESTUN.