330-0054

Check Active SLS Parameters

Navigate to MOD function → Machine Parameters → Safety → MP7760.x (SLS speed limit) and verify the configured speed limits match your application requirements.

Document current values before making changes for rollback purposes

Verify SLS Operating Mode

Check MP7750.x (SLS operating mode selection) to ensure the correct safety mode is configured for your current operation.

Changes to safety parameters require machine manufacturer authorization

Cross-Reference with Program

Compare the programmed S-values in your NC program with the SLS limits to identify conflicts.

Use the TNC's program simulation to verify speed commands before execution

Check Spindle Encoder Status

Navigate to Diagnosis → Axis Status and verify the spindle encoder signals are stable and within expected ranges during operation.

Ensure spindle is stopped before checking encoder connections

Verify Speed Feedback Scaling

Check MP4010 (spindle encoder resolution) and MP4020 (spindle gear ratio) parameters to ensure proper speed calculation.

Compare displayed speed with actual measured RPM using external tachometer

Test Encoder Signal Quality

Use the TNC's oscilloscope function (MOD → Diagnosis → Oscilloscope) to examine encoder signal integrity and look for noise or dropouts.

Check for proper encoder cable shielding and routing away from power cables

Check Safety Input Status

Navigate to MOD → Diagnosis → Safety Inputs and verify all SLS-related input signals (typically X121-X124) are showing correct states.

Never bypass safety inputs - contact machine manufacturer if signals are incorrect

Verify Safety Input Wiring

Inspect the physical wiring to safety input terminals for loose connections, damaged cables, or moisture ingress.

Use the TNC's input monitoring to observe signal transitions in real-time

Test Safety Device Operation

Verify that safety devices (door switches, light curtains) connected to SLS inputs are functioning properly and providing clean switching signals.

Check for proper 24V supply voltage to safety input circuits

Review Program S-Commands

Examine the NC program for S-values and verify they are within the SLS limits using the program editor's search function for 'S' commands.

Use the TNC's program overview function to quickly identify maximum S-values

Check Gear Range Selection

Verify that M41/M42/M43 gear range commands in the program are appropriate for the commanded spindle speeds and SLS limits.

Incorrect gear range can cause mechanical damage - verify with machine documentation

Validate Speed Transitions

Check that speed changes in the program don't create rapid transitions that could momentarily exceed SLS limits during acceleration.

Consider adding spindle acceleration limits using MP1082 if rapid speed changes are problematic

Check Safety Software Status

Navigate to MOD → Safety → Safety Status and verify the safety software signature is valid and no configuration errors are reported.

Safety software modifications require certified personnel and machine manufacturer approval

Verify Safety Parameter Integrity

Use the safety parameter comparison function to check for parameter corruption or unauthorized changes.

Keep backup copies of validated safety configurations for quick restoration

Contact Authorized Service

If safety software issues are confirmed, contact Heidenhain authorized service for safety software regeneration and validation.

Never attempt to modify safety software without proper certification and authorization