Code PRIO-490: Modbus TCP Server Error
Issue Description & Safety Warning
The Fanuc R-30i Series Robot Controller has triggered a critical Modbus TCP Server Error 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
Cause: The Modbus TCP Server running on the robot is enabled and has an error. Refer to additional cause code text for further details. Remedy: Alarm severity and last state behavior can be modified using the Modbus TCP Slave configuration screen. Refer to the Modbus Setup and Operations Manual for more information.
Source: FANUC Robot R-30iA Alarm Code List Operator's Manual
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Fanuc R-30i Series Robot Controller Alarms
Fanuc controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code PRIO-490 on the R-30i Series Robot Controller 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: 6553 Fanuc R-30i Series Robot Controller codes.
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