ABB Error 41555 — I/O unit / Bus cable / Process equipment fault
ErrorABB 41555 (“I/O unit / Bus cable / Process equipment fault”): Communication fault with a configured I/O unit: the cabinet cannot establish the link with a declared device (welding unit powered off, bus cable disconnected, unit missing). Likely part: Unité d'E/S / Câble de bus / Équipement process (Unité d'E/S / Câble de bus / Équipement process).
Updated 2026-10-22 · LogrobotLM reference
What it means
Communication fault with a configured I/O unit: the cabinet cannot establish the link with a declared device (welding unit powered off, bus cable disconnected, unit missing).
What to check
- Check that the equipment concerned is powered on.
- Check the bus cable and its connectors.
- Check the declaration of the unit in the I/O configuration and its address.
- Adjust the Unit Trustlevel if the unit is intentionally absent.
- Note: Code from the configuration/I/O domain, but whose root cause is almost always hardware. Read together with 71367 and 71424.
Part to check / replace
ABB 41555 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 →