FANUC Alarm PRIO-022 — SYST Too much I/O data on I/O link
Error- Hardware
- I/O Link and process I/O
- Controllers
- R-J3iB / R-30iA
- FANUC class
- SYSTEM
- Hardware family
- FANUC I/O Link, process I/O board, fuse and output alarms
FANUC PRIO-022 (“SYST Too much I/O data on I/O link”): The devices connected to the I/O Link exceed the I/O link capacity. First check: Disconnect some devices.
Updated 2026-10-22 · LogrobotLM reference
Description
The devices connected to the I/O Link exceed the I/O link capacity. A total of 64 bytes of data each are available for input and output devices connected to the I/O link. Process I/O boards typically use 16 bytes of input and 16 bytes of output each. Digital modules generally use one byte for each 8 ports. Analog modules generally use two bytes per port
Remedy
Disconnect some devices.
Field diagnosis
The total data of the connected modules exceeds the bus capacity (64 bytes of input and 64 of output; a process board typically uses 16 and 16).
What to check
- Remove modules or redistribute them onto a second bus.
- Note: Count the bytes before adding an analog module: two bytes per channel.
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 →