FANUC SV0410 Alarm: Excess Error at Stop and Troubleshooting

FANUC SV0410 means that the absolute value of a servo axis's position deviation exceeded the applicable limit while the CNC judged the axis to be stopped. On many FANUC systems, the English alarm text is SV0410 EXCESS ERROR (STOP), with the affected axis shown in the alarm message.

The first diagnostic decision is whether the alarm occurred during an ordinary servo-axis stop or while a tapping axis was stopped in rigid tapping. These conditions can use different limit parameters. For a normal servo axis, the relevant limit is generally parameter 1829. During rigid tapping, the applicable limit may instead be 5312, 5352, 5356, or 5360, depending on the spindle selected and the CNC series.

Example FANUC CNC alarm screen showing SV0410 on the X axis. The axis shown in parentheses changes with the affected machine axis.

For a wider alarm-number reference, see the FANUC SV Alarm Codes guide.

What Does FANUC SV0410 Mean?

A FANUC servo system continually compares the commanded position with the position returned by the motor pulse coder or the configured position detector. The difference is the position deviation, also called position error or following error. A small deviation is normal while the servo loop is correcting position. SV0410 is generated when the deviation becomes greater than the permitted stop-state value.

This does not necessarily mean that an encoder has detected obvious continuous axis movement. A large position-error value can also be produced when the axis cannot reach or hold the commanded position, the servo is hunting, the mechanism is obstructed, the feedback and motor connections do not match, or the control data is unsuitable for the installed motor and machine.

The FANUC 0i-F Parameter Manual B-64610EN/01 states that when stop-state position deviation exceeds the value set in parameter 1829, SV0410 is generated and operation stops immediately, in the same manner as an emergency stop. The related position-error value is displayed in diagnosis 300 on applicable systems.

Determine Which Position-Deviation Limit Applies

Do not change parameter 1829 simply because the screen shows SV0410. First identify the operating condition in which the alarm occurred.

Parameters 5312, 5352, 5356, and 5360 apply to the tapping axis, not to the spindle's own position error. In the same 0i-F manual, parameter 5313 is the stop-state positional-deviation limit for the spindle during rigid tapping. Do not substitute spindle and tapping-axis parameters for one another.

There are also differences between CNC generations. For example, the 0i-C Parameter Manual B-64120EN/01 describes configurations in which parameter 5312 can also apply to the second spindle when the relevant spindle-selection setting is disabled, while parameter 5352 is used when separate second-spindle data is enabled. Always use the parameter manual for the exact CNC series, software, spindle configuration, and machine.

1. Record the Alarm and the Operating Condition

Before resetting the control, record:

• The complete alarm message and affected axis

• The CNC series and software version

• The servo amplifier and motor model numbers, including suffixes

• Whether the alarm occurred at power-up, after motion stopped, during rigid tapping, after an emergency stop, or after maintenance

• Any simultaneous servo, pulse-coder, FSSB, overcurrent, or machine alarms

• Whether the axis vibrated, drifted, struck an obstruction, or failed to reach position

This information determines which diagnostic path is relevant. An X-axis SV0410 immediately after a cable change is not investigated in the same order as a Z-axis SV0410 that occurs only at the bottom or reversal point of a rigid-tapping cycle.

On 0i-F systems equipped with the trouble-diagnosis function, FANUC uses SV0410 as an example of reviewing stored servo information and the torque-command waveform immediately before the alarm. Preserving the alarm history and latched data can therefore be more useful than repeatedly resetting the CNC.

2. Check the Position Deviation Before Changing the Limit

For an ordinary servo-axis stop, review diagnosis 300 for the affected axis and compare its absolute value with the current parameter 1829 setting. Also check whether the error decays toward zero after motion or remains unstable while the axis is commanded to hold position.

For rigid tapping, confirm which spindle was selected and review the rigid-tapping diagnostic data supported by the control. On the cited 0i-F system, these include spindle position error in diagnosis 450 and synchronization-related values in diagnoses 452 through 462. The available numbers and meanings must be confirmed in the applicable maintenance manual.

Back up the existing CNC and servo data before making any authorized parameter change. Record the original value, the reason for the change, and the test result. Do not increase a deviation limit merely until the alarm disappears. A larger limit can mask a mechanical, wiring, feedback, or servo-adjustment problem and permits more following error before the CNC stops the machine.

3. Check for Mechanical Resistance, Collision, or Axis Drift

FANUC's 0i-F trouble-diagnosis material identifies mechanical collision or twist as a probable cause of SV0410 because it can prevent an axis from reaching its target position. Inspect the machine for conditions such as:

• Chips, covers, fixtures, tools, or workpieces obstructing travel

• Binding ballscrew, damaged bearing, poor lubrication, or excessive friction

• Loose coupling, damaged transmission component, or excessive backlash

• Gravity-driven movement on a vertical or inclined axis

• A rotary-axis clamp or machine brake that engages or releases at the wrong time

The brake or clamp check is machine-specific. A fourth axis does not automatically use the same brake sequence as another machine, and a motor holding brake is not a substitute for servo position control during normal energized operation. Verify the machine builder's ladder sequence, hydraulic or pneumatic state, and mechanical procedure before adjusting the servo.

4. Check for Vibration, Hunting, or Unsuitable Servo Adjustment

If the affected axis oscillates or hums while stopped, SV0410 may be a result of instability rather than the primary fault. FANUC's 0i-F diagnostic example specifically evaluates the torque-command waveform for vibration.

Check for mechanical looseness, resonance, excessive gain, incorrect load inertia, and recent changes to servo tuning. Compare the condition with a known-good backup and with the machine builder's approved servo data. Do not randomly lower gain or reinitialize the axis, because incorrect initialization can change motor identification, detector settings, direction, reference-position behavior, and safety-related machine operation.

Servo initialization is a reasonable field-service check only when there is evidence that parameters were lost, corrupted, loaded from the wrong machine, or changed during motor, amplifier, CNC, or memory replacement. Restore or initialize data only from a verified machine-specific source and retest the complete axis afterward.

5. Inspect Motor Power and Feedback Connections After Service Work

Cable checks become especially important when SV0410 begins immediately after motor, amplifier, encoder, or cabinet work. With power isolated and the DC link safely discharged, verify connector identity, axis labels, pin condition, shielding, grounding, and cable routing according to the applicable FANUC and machine-builder drawings.

If two axes begin showing SV0410 after maintenance, confirm that neither the motor power cables nor the feedback cables were exchanged between axes. A connected cable is not necessarily connected to the correct motor or amplifier channel.

Do not swap cables while powered and do not use trial-and-error rewiring as a diagnostic method. An incorrect motor/feedback pairing can create unexpected motion. Any test after reconnection must follow the machine builder's commissioning and reference-position procedure.

6. Verify a Repaired or Rewound Servo Motor

The technician-supplied note about phase sequence is relevant only when the motor has been disassembled, rewound, had its coils or internal leads replaced, or has an uncertain repair history. In that case, qualified servo personnel should verify the motor phases, pulse-coder alignment, motor identification, brake wiring, insulation, and feedback relationship against the correct FANUC specification.

Do not simply exchange two motor phases to see whether SV0410 clears. FANUC servo motors and amplifiers depend on the correct relationship between current control and rotor-position feedback. An incorrect relationship can cause violent motion, overcurrent, motor damage, or additional alarms.

7. Evaluate the Servo Amplifier Only After the External Checks

A defective servo amplifier can be considered when the axis cannot produce stable torque or hold position even though the mechanics, motor, cables, feedback, and machine-specific parameters have been verified. However, SV0410 alone does not prove that the amplifier is damaged, and FANUC does not define amplifier replacement as the universal first action for this alarm.

Review the amplifier status and all simultaneous alarms. If a substitution test is needed, use an exact compatible unit and preserve the original servo configuration. Verify the complete model and suffix rather than selecting a drive only by physical appearance or power rating. REACO CNC can help check or source compatible FANUC servo, spindle, and power drives.

Rigid-Tapping-Specific SV0410 Checks

When SV0410 occurs only during rigid tapping, confirm all of the following before changing 5312 or its spindle-specific equivalent:

• The alarm occurs while the tapping axis is stopping or reversing in the rigid-tapping cycle

• The CNC selected the expected first, second, third, or fourth spindle

• The applicable stop limit is 5312, 5352, 5356, or 5360 for that control configuration

• The rigid-tapping loop gain, acceleration/deceleration, detector resolution, gear ratio, and spindle-selection data match the machine

• The tapping axis and spindle are mechanically free and do not bind at the alarm point

• The tool, pitch, feed, spindle speed, and programmed depth do not create an abnormal load

• The rigid-tapping position-error and synchronization diagnostics are reviewed before data is changed

Changing only the limit can conceal a synchronization or mechanical problem. If the alarm follows one spindle but not another, compare the selected-spindle data and the separate rigid-tapping parameter sets instead of treating the condition as a general axis fault.

Difference Between SV0410 and SV0411

Do not diagnose the alarm by the phrase “excess error” alone. Record whether the CNC shows 410 or 411 and whether the event occurred during an ordinary axis move or rigid tapping. For the moving-state alarm, see the FANUC SV0411 Excess Error During Movement guide.

FANUC SV0410 Diagnostic Table

Recommended Troubleshooting Order

1. Record the complete SV0410 message, affected axis, operating mode, alarm history, and simultaneous alarms.

2. Determine whether the event occurred during an ordinary servo-axis stop or during rigid tapping.

3. Preserve the current parameters and latched diagnostic data before resetting or editing anything.

4. For a normal stop, compare diagnosis 300 with parameter 1829. For rigid tapping, identify the selected spindle and the applicable 5312/5352/5356/5360 limit.

5. Inspect the axis for collision, binding, poor lubrication, drift, incorrect clamp/brake timing, or abnormal cutting load.

6. Check for vibration or hunting and compare servo data with the verified machine backup.

7. If service work preceded the alarm, verify motor-power and feedback-cable assignment, connectors, shielding, and grounding.

8. If the motor was repaired or rewound, have its phase and feedback relationship professionally verified.

9. Consider servo-amplifier testing only after the external causes and machine data have been checked.

10. Retest at a safe speed and under the machine builder's procedure, then confirm that the position deviation remains stable rather than merely increasing the alarm threshold.

Technical References

• FANUC Series 0i-MODEL F Maintenance Manual, B-64605EN/01, trouble diagnosis and servo diagnosis data

• FANUC Series 0i-MODEL F Parameter Manual, B-64610EN/01, parameters 1829, 5312, 5352, 5356, and 5360

• FANUC Series 0i-MODEL C / 0i Mate-MODEL C Parameter Manual, B-64120EN/01, rigid-tapping parameters and spindle-selection conditions

• Applicable FANUC servo motor and servo amplifier maintenance/parameter manuals for the installed motor and amplifier series

Always use the manual edition that applies to the exact CNC, software, servo motor, amplifier, detector, spindle configuration, and machine. Parameter modification, powered testing, motor wiring work, and drive replacement must be performed by qualified personnel under the machine builder's safety procedure.

Need Help With FANUC SV0410 Alarm?

REACO CNC provides independent FANUC alarm analysis, servo amplifier testing and repair, motor and feedback-system checks, parameter compatibility support, and replacement-drive supply. Send us the complete alarm screen, CNC model, servo amplifier model and suffix, motor model, affected axis, current parameter values, and a description of exactly when the alarm occurs.

Visit the FANUC Technical Support Center for more FANUC alarm guides, or contact REACO CNC for assistance.

Reference Source: Beijing FANUC. This article is based on FANUC technical documentation. The applicable limit parameter and troubleshooting procedure depend on the exact CNC, software, servo system, rigid-tapping configuration, and machine.