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ABB Error 39521 — Drive module communication warning

Warning

ABB 39521 (“Drive module communication warning”): Drive module communication warning: a high number of communication errors is detected on the Ethernet link to the drive module, without a complete break of the link. Likely part: Liaison Ethernet / CEM (link Ethernet / CEM).

Updated 2026-10-22 · LogrobotLM reference

What it means

Drive module communication warning: a high number of communication errors is detected on the Ethernet link to the drive module, without a complete break of the link.

What to check

  • Look for external sources of electromagnetic interference along the cable (power cables, process drives, welding unit).
  • Rework the cable route and the grounds/shields.
  • Replace the suspect Ethernet cable before it causes a 39520.
  • Note: Precursor signal of the 39520 break; typically observed in spot welding environments.

Part to check / replace

ABB 39521 points to the hardware below — start here before ordering.

Tap a part for every code that points to it — and verify the exact variant for your controller before ordering.

Related codes

32540Drive unit / firmware fault32541Drive unit / firmware fault39008Drive units fault

Indicative field information — the robot manufacturer's manual and safety procedures always prevail. Never bypass a safety device; apply lockout/tagout (LOTO) before any physical intervention. How this reference is built →