What causes Siemens SINUMERIK alarm 28030?

Parameter or machine data configuration error. Hardware fault on the NC or drive component. Part program error or illegal command. Communication fault between NC and drive or I/O modules. Software or firmware error requiring system restart.

How do I fix Siemens SINUMERIK alarm 28030?

1. Note the complete alarm text including any axis, channel, or block number values. 2. Check for related alarms active simultaneously in the SINUMERIK alarm list. 3. Power cycle the machine to clear transient faults. 4. Review the SINUMERIK machine data for parameters related to the alarm. 5. Consult the Siemens SINUMERIK alarm manual for alarm 28030 detailed remedy.

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Siemens SINUMERIK Controller

Servo/Axis · Intermediate · 30-120 minutes

Alarm 28030

Siemens 840D 28030 - Serious alarm on NCU, axes in follow-up mode

Alarm 28030 is triggered when a serious alarm occurs on a different NCU (Numerical Control Unit) in a multi-NCU system, causing all axes on the reporting NCU to enter follow-up mode (Folgeregelung). This is a dependent alarm indicating loss of synchronization capability between NCUs due to a fault on the primary or coordinating NCU.

Siemens SINUMERIKServo/AxisIntermediate30-120 minutes

28030

Siemens 840D 28030 - Serious alarm on NCU, axes in follow-up mode

Serious alarm on NCU, axes in follow-up mode

Root Cause Summary

Alarm 28030 is triggered when a serious alarm occurs on a different NCU (Numerical Control Unit) in a multi-NCU system, causing all axes on the reporting NCU to enter follow-up mode (Folgeregelung). This is a dependent alarm indicating loss of synchronization capability between NCUs due to a fault on the primary or coordinating NCU.

Safety

Refer to Siemens documentation
Ensure qualified technician performs repairs

Causes and Fixes

1
Check NCK diagnostics on the partner NCU via HMI path: Diagnostics > System Information > NCU Status. Identify which NCU generated the serious alarm by reviewing the NCU alarm buffer (last 10-20 alarms).
Do not attempt to clear this alarm until the causative serious alarm on the partner NCU is resolved.
2
Review parameter MD32100 (CouplingMode) and MD32101 (CoupleNCUNumber) to confirm multi-NCU coupling configuration. Verify the NCU number in the alarm message (%1 placeholder) matches the configured secondary NCU.
3
Resolve the serious alarm on the identified NCU. Check its servo drives (parameter MD30120 for servo enable), encoder connections, and interpolator status via NCK > Servo > State displays.
4
After resolving the partner NCU fault, axis coupling automatically re-engages and follow-up mode is exited. Reset alarm via HMI Alarm menu or PLC reset if coupling mode SD42100 requires re-initialization.

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