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FANUC 0i-F SV0411 on B axis during movement, what to check?

CNCFANUC0I FSV0411
Question

I'm getting a FANUC SV0411 alarm on my machine's B axis (rotary table) when it tries to move. It happens right at the start of the move, after the clamp releases. What should I check first?

Top answer · Written by InduQT from the fault guide and manufacturer manuals cited below · Nov 4, 2026

FANUC SV0411 (EXCESS ERROR (MOVING)) on a 0i-F controller means the B axis motor couldn't keep up with the commanded motion, and its positional deviation exceeded the limit in parameter 1828. Since it happens right at the start of the move after the clamp releases, the most likely causes are the rotary brake not fully releasing or a mechanical issue with the B axis itself.

Likely causes and checks

1Rotary brake not releasing

Points to it
The alarm occurs right at the start of the first move after the B axis clamp releases. This suggests the brake is still engaged or not fully disengaging, preventing the motor from turning.
Check
Isolate and lock out the machine, then check the brake wiring against the machine builder's diagram. With power restored, listen for the brake releasing when servo power comes on and confirm the clamp-released signal before the B axis is commanded to move.

2Mechanical binding or crash

Points to it
The alarm happens consistently at the start of a move, or after a known collision. Jogging the B axis slowly might feel rough, noisy, or require excessive force.
Check
Isolate and lock out the machine. Disconnect the motor from the B axis (if possible) and manually rotate the axis to check for free movement, binding, or obstructions. Inspect the rotary bearing, gear reducer, and any clamping mechanisms for damage or chips.

3Load or acceleration beyond motor capability

Points to it
The alarm only occurs during heavy cuts, fast rapids, or with a heavy workpiece on the table. There are no obvious mechanical issues or brake problems.
Check
On the CNC diagnosis screen, watch the actual positional deviation (DGN 300) during the move and compare it to parameter 1828. Review the programmed feedrate, acceleration settings, and cutting conditions for the B axis. Consider if the workpiece weight is within the axis's rated capacity.

4Power or feedback cable fault

Points to it
The alarm is intermittent, sometimes only at certain B axis positions where the cable flexes. It might occasionally be accompanied by Pulsecoder alarms (SV0368, SV0446).
Check
Isolate and lock out the machine. Visually inspect the motor power and Pulsecoder cables for damage, especially where they flex. Disconnect the cables from the amplifier and motor, then insulation-test the power cable and motor windings.

Next check: If the brake and mechanical checks don't reveal the issue, monitor the actual positional deviation (DGN 300) during the move to see how close it gets to the parameter 1828 limit before tripping. This can help differentiate between a load issue and a parameter mismatch.

What it typically looks like in the data

B axis commanded to moveSV0411 Alarm0 s2 s4 s6 s8 s10 s100Commanded Position (deg)1-1Actual Position (deg)100SV0411 Limit (P1828)Positional Deviation (deg)10.20Motor Current (A)
Positional deviation rapidly increases and exceeds the limit when the B axis attempts to move. Illustrative, synthetic data showing the typical pattern, not a recording from a real machine; values vary by machine and settings.
Work on fuel trains, burners, pressure vessels and electrical equipment must be done by qualified personnel following the manufacturer’s documentation and local codes. Never bypass a safety device or interlock.

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