Code SRVO-057: FSSB disconnect (G:%d A:%d)
Issue Description & Safety Warning
The Fanuc R-30i Series Robot Controller has triggered a critical FSSB disconnect (G:%d A:%d) 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: Communication was interrupted between the main board and the servo amplifier. Remedy: 1. Check whether fuse F3 in the power supply unit has blown. 2. Check whether fuse FS1 in the servo amplifier has blown. 3. Check the communication cable (optical fiber) between the main board and servo amplifier. Replace it if it is faulty. Note: Before executing the next step, perform a complete controller backup to save all of your programs and settings. Refer to the Application-specific Setup and Operations Manual for more information. 4. Replace the axis control card on the main board. 5. Replace the servo amplifier. 6. Check the robot connection cable RP1 (+5V ground fault). 7. Replace the main board.
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 SRVO-057 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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