300401

Check Following Error Display

Navigate to Diagnostics > Service > Axis Status and observe the following error value for the affected axis during movement.

Following error should typically be less than 0.1mm for linear axes and 0.01° for rotary axes during normal operation.

Verify MD32200 Setting

Check machine data MD32200[AX] FOLLOWING_ERR_WINDOW value. Compare against actual following error observed in step 1.

Do not increase this value beyond 10x the normal following error without investigating root cause.

Inspect Mechanical System

Check for mechanical binding, worn ballscrews, or coupling issues that could cause position lag. Manually move axis if safe to do so.

Ensure axis is disabled and machine is in safe state before manual movement.

Optimize Servo Parameters

Access Parameters > Machine Data > Servo and review KV factor (MD32000) and integral time (MD32010) for proper tuning.

Use SINUMERIK Servo Trace to analyze position loop performance before adjusting parameters.

Check Drive Status LEDs

Examine SINAMICS drive unit status LEDs. Green = ready, red = fault, yellow = warning. Note any fault codes on drive display.

High voltage present - follow lockout/tagout procedures.

Verify Drive Enable Chain

Navigate to Diagnostics > PLC > I/O Status and verify drive enable signals (typically DB380x.DBX0.0 for axis enable).

Check emergency stop circuit and safety door interlocks in the enable chain.

Monitor DC Bus Voltage

In SINAMICS Startdrive or HMI Diagnostics, check DC link voltage (r0026). Should be ~565V for 400V supply.

Low DC bus voltage indicates power supply issues that require immediate attention.

Review Drive Fault Buffer

Access drive fault buffer via r0945[0-7] parameters to identify specific drive faults that may have caused the monitoring error.

Check Encoder Signal Quality

Navigate to Diagnostics > Drive > Encoder and monitor encoder signals. Check for consistent A/B quadrature and Z-pulse integrity.

Use oscilloscope on encoder signals if available - look for 1Vpp differential signals with 90° phase shift.

Verify Encoder Parameters

Check MD31020 (ENC_RESOL) encoder resolution matches physical encoder. Verify MD34200 (POSCTRL_GAIN) is correctly calculated.

Incorrect encoder resolution will cause position scaling errors and monitoring faults.

Inspect Encoder Connections

Check encoder cable connections at motor and drive. Look for loose pins, damaged cables, or EMI interference sources nearby.

Encoder cables should be shielded and routed away from power cables to prevent EMI.

Test Reference Point Approach

Attempt reference point approach (G74) to verify encoder Z-pulse detection and position initialization.

Ensure adequate clearance for reference point movement before executing.

Review Monitoring Window Settings

Check MD32200 (FOLLOWING_ERR_WINDOW), MD32210 (STANDSTILL_WINDOW), and MD32220 (POSITIONING_TIME) for appropriate values.

Monitoring windows should be 2-3x larger than typical operating deviations but not so large as to miss real faults.

Analyze Velocity Monitoring

Verify MD32400 (VELO_FFW_TIME) and MD32410 (MAX_AX_VELO) settings match machine capabilities and programming requirements.

Overly restrictive velocity monitoring can cause alarms during rapid traverse moves.

Check Acceleration Limits

Review MD32300 (MAX_AX_ACCEL) and MD32310 (MAX_AX_DECEL) against actual machine dynamics and servo drive ratings.

Use SINUMERIK Trace to record actual acceleration profiles and compare against configured limits.

Inspect for Physical Damage

Visually examine axis components, tool holder, workpiece setup for signs of collision or binding.

Machine may be damaged - do not attempt movement until thorough inspection is complete.

Check Motor Current

Monitor drive current (r0027) during attempted movement. Excessive current indicates mechanical binding or overload.

Normal cutting current should be 30-70% of motor rated current. Above 90% indicates overload condition.

Verify Load Conditions

Review part program for excessive feed rates, inappropriate cutting parameters, or rapid direction changes that could overload the axis.

Reduce feed rates and cutting parameters until normal operation is restored.