ABB Error 0121 — Link computer fault
ErrorABB 0121 (“Link computer fault”): Error detected during the self-tests on the serial communication link. Likely part: Liaison Calculateur (link computer).
Updated 2026-10-22 · LogrobotLM reference
What it means
Error detected during the self-tests on the serial communication link.
What to check
- Replace the computer board if the extension serial link is to be used.
- Note: Similar to serial channel faults 31108 on S4.
Part to check / replace
ABB 0121 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
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 →