What causes Siemens SINUMERIK alarm 4402?

Machine data was changed requiring acknowledgment or power cycle. System configuration change notification. Commissioning or service operation generated this notice. Axis or drive configuration change affecting machine data.

How do I fix Siemens SINUMERIK alarm 4402?

1. Read the complete notice text on the SINUMERIK screen. 2. If a power cycle is indicated, perform a controlled machine power off and restart. 3. If machine data backup is indicated, save the current machine data. 4. Acknowledge the notice and verify the system is operating correctly after the change. 5. Consult the machine commissioning engineer if the notice is unexpected.

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Siemens SINUMERIK Controller

Parameter · Intermediate · 30-120 minutes

Alarm 4402

Siemens 840D 4402 - causes a machine data reset

Alarm 4402 is triggered when a machine data parameter (MD) is flagged with the reset-on-startup attribute, causing all current MD values to be overwritten with factory defaults at the next system ramp-up. This alarm warns of potential data loss in both volatile and battery-backed memory regions, particularly affecting custom machine configurations and tuning parameters stored in the NCK (Numerical Control Kernel) memory.

Siemens SINUMERIKParameterIntermediate30-120 minutes

4402

Siemens 840D 4402 - causes a machine data reset

causes a machine data reset

Root Cause Summary

Alarm 4402 is triggered when a machine data parameter (MD) is flagged with the reset-on-startup attribute, causing all current MD values to be overwritten with factory defaults at the next system ramp-up. This alarm warns of potential data loss in both volatile and battery-backed memory regions, particularly affecting custom machine configurations and tuning parameters stored in the NCK (Numerical Control Kernel) memory.

Safety

Refer to Siemens documentation
Ensure qualified technician performs repairs

Causes and Fixes

1
Access the NCK Parameter menu via HMI: Diagnostics > Machine Data > Machine Data Editor. Identify which MD parameter is flagged for reset by searching for parameters with the 'Reset at Startup' attribute enabled.
Do not proceed to Step 2 until you have identified the specific MD parameter causing the alarm.
2
Document all current MD values before any reset occurs. Use the 'Backup Machine Data' function in the HMI (typically found under Maintenance > Backup/Restore) or export via SINUMERIK Settings to an external file on a USB drive.
3
Disable the reset-on-startup flag by clearing the initialization attribute on the identified MD parameter. Navigate to the parameter properties and uncheck 'Initialize on Startup' or equivalent option in your HMI version (840D or 840D sl).
4
Perform a controlled system ramp-up (soft reset) via Diagnostics > System Functions > Ramp-up. Monitor the system initialization sequence to confirm no unintended machine data loss occurs.

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