What causes Siemens SINUMERIK alarm 2001?

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 2001?

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 2001 detailed remedy.

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Siemens SINUMERIK Controller

System · Intermediate · 30-120 minutes

Alarm 2001

Siemens 840D 2001 - PLC has not started up

Alarm 2001 indicates the PLC failed to transmit a heartbeat signal (sign of life) to the NCK within the timeout window specified by MD 10120 PLC_RUNNINGUP_TIMEOUT. This typically occurs during system startup when the PLC processor is either not executing, blocked in initialization, or experiencing communication failure with the NCK subsystem.

Siemens SINUMERIKSystemIntermediate30-120 minutes

2001

Siemens 840D 2001 - PLC has not started up

PLC has not started up

Root Cause Summary

Alarm 2001 indicates the PLC failed to transmit a heartbeat signal (sign of life) to the NCK within the timeout window specified by MD 10120 PLC_RUNNINGUP_TIMEOUT. This typically occurs during system startup when the PLC processor is either not executing, blocked in initialization, or experiencing communication failure with the NCK subsystem.

Safety

Refer to Siemens documentation
Ensure qualified technician performs repairs

Causes and Fixes

1
Access HMI Panel > Diagnostics > System Information and verify PLC Status shows 'RUN' (not 'STOP', 'STARTUP', or 'ERROR'). Compare against expected runtime displayed in System > Status page.
2
In NCK > Diagnose menu, check PLC_RUNNINGUP_TIMEOUT value in MD 10120. Default is 1000 ms. If timeout is set too low (<500 ms), increase to 2000 ms to allow slower PLC initialization on first startup.
Modifying MD 10120 requires machine lock-out. Store parameter change and perform controlled system restart via Siemens HMI reset function.
3
Perform PLC firmware reload: Access Machine > PLC > Reload/Restore. Download current PLC source code to CPU if available, or reload from backup. Monitor PLC LED indicators during load sequence (typically flash green during load, solid green when RUN achieved).
PLC reload erases runtime data. Backup any SD (static data) parameter values before reload.
4
If PLC remains in non-RUN state, check OB 100 (startup organization block) source code for blocking WAIT instructions or communication calls that exceed timeout threshold. Recommend Siemens support intervention for PLC source code audit.

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