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Check Drive Status Display

Navigate to Diagnostics > Drive > Status and examine the drive ready signals for all geometry axes. Look for red status indicators or fault codes.

Use HMI softkey 'Drive Status' for quick overview of all axis drive conditions

Verify Drive Parameters

Check MD36300 (SERVO_ENABLE_DELAY) and MD36310 (DRIVE_READY_TIMEOUT) settings. Verify drive-specific parameters match actual hardware configuration.

Incorrect servo enable timing can cause spurious enable drops during rapid acceleration

Examine Drive Diagnostics

Access Service > Drive Diagnostics and review the drive's internal fault buffer. Clear any historical faults and monitor for recurring drive ready losses.

Drive ready signal is typically monitored via X121/X122 connector pins on SINAMICS drives

Check PLC Safety Status

Navigate to Diagnostics > PLC > I/O Status and examine all safety-related inputs. Verify E-stop circuits, safety doors, and enable switches are active.

Never bypass safety circuits - identify and resolve the root safety issue

Monitor DB31 Enable Signals

Use PLC > Variable Status to monitor DB31.DBX2.1 for each geometry axis in real-time. Observe signal behavior during motion commands.

Set up a trace function to capture the exact timing of enable signal dropout relative to motion commands

Review Safety PLC Logic

Examine the PLC program logic that controls servo enables. Check for timing issues, contact bounce, or incorrect safety relay specifications.

Look for MD11060 (SAFE_STOP_DELAY) settings that may be too aggressive for your safety hardware response time

Check Encoder Status

Navigate to Diagnostics > Axis > Encoder and verify all position feedback systems show 'OK' status. Look for encoder alarm history in the alarm buffer.

Absolute encoder battery low conditions often cause intermittent feedback losses

Verify Encoder Parameters

Check MD31020 (ENC_TYPE) and MD31030 (ENC_RESOL) match actual encoder specifications. Verify encoder interface settings in MD31xxx parameter group.

Incorrect encoder resolution settings can cause position monitoring faults during high-speed motion

Test Encoder Signals

Use Service > Encoder Test function to verify signal quality. Check for noise, amplitude variations, or intermittent connections in encoder cables.

EnDat and BiSS encoder communication errors often show up in the drive's encoder diagnostic registers

Check Following Error Limits

Navigate to Machine > Axis Parameters and verify MD36610 (MAX_FOLLOWING_ERROR) settings are appropriate for your servo system performance.

Following errors often spike during rapid direction changes - check MD36620 (FOLLOWING_ERROR_TIME) for proper filtering

Review Velocity Monitoring

Check MD36640 (MAX_VELOCITY_DEVIATION) and related velocity monitoring parameters. Verify these limits accommodate your application's motion profile requirements.

Overly restrictive velocity monitoring can cause nuisance servo disables during normal operation

Analyze Motion Traces

Use Diagnostics > Trace to capture actual vs. commanded position and velocity during the fault condition. Look for servo tuning issues or mechanical binding.

Enable trace triggers on servo enable signals to capture the exact motion conditions when the fault occurs