Code SRVO-040: Mastered at mark pos(G:%d)
Issue Description & Safety Warning
The Fanuc R-30i Series Robot Controller has triggered a critical Mastered at mark pos(G:%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: Zero position master is done with mark position (not with zero position). Remedy: This message is only for S-420iR. S-420iR has the mark at non-zero position for J2 and J3. So Zero position master is not done with zero pos for S-420iS. Confirm the position of each axis to be at mark position. If the robot is not S-420iR, $scr_grp.$robot_model may be wrong. Set correct $scr_grp.$robot_model.
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-040 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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