Code ER68: I/O Link i TOO MANY ASSIGNMENTS IN HIGH
Issue Description & Safety Warning
The Fanuc 30i/31i/32i CNC has triggered a critical I/O Link i TOO MANY ASSIGNMENTS IN HIGH alarm. Immediate attention from a qualified operator or maintenance technician is required to prevent secondary damage to the equipment or spoiled parts during the manufacturing cycle. Always ensure standard safety and LOTO procedures are followed before accessing electrical cabinets.
Official Troubleshooting Steps
SPEED MODE (CHn,Gyy) (Note1) (Note3) When a group in the high-speed transfer cycle mode is connected to I/O Link i, correct assignment so that the assignment for each group is performed within the quartered transfer timing with referencing the PMC programming manual (B-64513EN). In CHn, assignment could not be made to group yy and following because the transfer capacity limit was exceeded in transfer timing assignment processing when the high-speed mode of I/O Link i is used.
Source: Fanuc Series 30i/31i/32i-A Maintenance Manual, Appendix A Alarm List — PMC alarms (B-64485EN/01)
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Fanuc 30i/31i/32i CNC Alarms
Fanuc controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code ER68 on the 30i/31i/32i CNC identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Fanuc's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 85 Fanuc 30i/31i/32i CNC codes.
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