What the A.810 alarm means

Both the encoder supply and the battery supply failed, so absolute position data was lost; the axis must be re-referenced (zeroing) before use. This fault appears in a large share of our Yaskawa DX100 / DX200 / YRC1000 service tickets, and the first round of on-site checks usually finds the source.

Most common causes

  • Dead or missing encoder backup battery
  • Battery connector loose or corroded
  • Power removed while encoder supply was already down
  • Absolute encoder itself faulty
Field note: Most of the time the problem is the first item on the list, so ruling it out saves you half the time.

Step-by-step field fix

  1. Replace the encoder backup battery with a fresh one
  2. Inspect the battery holder and connector
  3. Run the absolute-encoder setup/zeroing procedure on the affected axis
  4. Move each axis to its mechanical scribe mark and verify the zero values
  5. Replace the encoder/motor if the alarm returns after setup
Safety first: For YASKAWA a-810, encoder alarms often mean position data cannot be trusted: actual pose may disagree with the system record, so releasing a brake or jogging carries unexpected-motion risk. What you can check yourself first is Replace the encoder backup battery with a fresh one; position feedback and brake release handling is not a DIY job.

How we diagnose encoder alarms on site

YASKAWA a-810 belongs to the encoder & position family. On YASKAWA a-810 the failing stage is absolute encoders with a battery box; low battery voltage raises the encoder-battery alarms on the DX100 / DX200 / YRC1000 / YRC1000micro - the feedback path: encoder body, encoder cable, battery, measuring board and the stored position memory. We start reading YASKAWA a-810 at the pendant alarm list (A / E / 4xxx segments) together with the servo drive's digit display.

The chain involved in YASKAWA a-810 runs: motor-side encoder -> encoder cable -> drive / measuring board acquisition -> position count and zero data -> battery-held memory.

On YASKAWA a-810 the commonest field report is Dead or missing encoder backup battery; the highest-share cause is plain: The highest-share cause in this family is unglamorous: battery voltage. Absolute encoders hold the position count on a battery while power is off; below threshold the memory is gone and the controller demands a fresh master. Packs are designed for roughly two to three years, but a hot cabinet shortens that a lot. We carry spare packs, and after a swap we master immediately and re-check every axis zero so the customer does not run on an offset.

Field notes on this page cover YASKAWA a-810 (Encoder Backup Error — Position Lost); written by the Henghuan repair team, updated 2026-10-01.

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Related Encoder & Position alarms

A.830 — Absolute Encoder Battery Error A.C90 — Encoder Communications Error
Same family: this code belongs to the Encoder & position alarms family - the page collects all Encoder & position-family codes we have handled, with the common inspection order and spares.
Other brands: we also keep field-fix libraries for Universal Robots · Kawasaki · Staubli and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the YASKAWA a-810 alarm mean?

Both the encoder supply and the battery supply failed, so absolute position data was lost; the axis must be re-referenced (zeroing) before use. This fault appears in a large share of our Yaskawa DX100 / DX200 / YRC1000 service tickets, and the first round of on-site checks usually finds the source. YASKAWA a-810 sits in the encoder & position family; on our work orders the highest-frequency trigger for this code is "Dead or missing encoder backup battery".

QCan I clear a YASKAWA a-810 alarm myself?

Whether YASKAWA a-810 clears on its own depends on the outcome of "Replace the encoder backup battery with a fresh one". Finish the flow with "Replace the encoder/motor if the alarm returns after setup" to confirm YASKAWA a-810 - do not skip it. If that step is clean, the second most frequent cause on YASKAWA a-810 is "Battery connector loose or corroded". When YASKAWA a-810 keeps coming back it is not a one-off trigger - especially if Replace the encoder/motor if the alarm returns after setup is where you get stuck. Do not keep producing through YASKAWA a-810.

QFor encoder alarms like YASKAWA a-810, can it be fixed in one visit?

The commonest causes we see on YASKAWA a-810 are "Dead or missing encoder backup battery, Battery connector loose or corroded, Power removed while encoder supply was already down", so we stock the van against those. For YASKAWA a-810 specifically, we carry feedback-path parts: encoder cables, battery packs, connector pins and the measuring-board type data for the brand. For YASKAWA a-810, encoder alarms are mostly broken cores and dead batteries, both of which ride in the van, so most clear in one visit. Before we roll, tell us what YASKAWA a-810 shows on the pendant alarm list (A / E / 4xxx segments) together with the servo drive's digit display and what the machine was doing - phone or video triage is free.

This page on YASKAWA a-810 was written by the Henghuan Robotics repair team from field service experience. Alarm descriptions are our own summary for troubleshooting reference and may vary by controller and software version — when in doubt, check your Yaskawa documentation or contact us. Henghuan is an independent service provider, not affiliated with or endorsed by Yaskawa.