What causes Siemens SINUMERIK alarm 6402?

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 6402?

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 6402 detailed remedy.

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Siemens SINUMERIK Controller

Tool Changer · Intermediate · 30-120 minutes

Alarm 6402

Siemens 840D 6402 - Channel tool change not possible. Magazine no. not available

Alarm 6402 fires when the NCK attempts to execute a tool change command referencing a magazine number that is not configured or available in the SINUMERIK 840D tool management system. This occurs when the magazine index specified in the M6/T command does not match any configured magazine in the machine data or when the magazine interface is not initialized.

Siemens SINUMERIKTool ChangerIntermediate30-120 minutes

6402

Siemens 840D 6402 - Channel tool change not possible. Magazine no. not available

Channel tool change not possible. Magazine no. not available

Root Cause Summary

Alarm 6402 fires when the NCK attempts to execute a tool change command referencing a magazine number that is not configured or available in the SINUMERIK 840D tool management system. This occurs when the magazine index specified in the M6/T command does not match any configured magazine in the machine data or when the magazine interface is not initialized.

Safety

Refer to Siemens documentation
Ensure qualified technician performs repairs

Causes and Fixes

1
Access Siemens HMI > Maintenance > Machine Data > scroll to MD 31000 (ToolMagazineNumber). Verify the magazine number referenced in alarm %2 is listed and enabled.
Do not modify machine data while CNC is in AUTO mode or during tool change execution.
2
Cross-reference the NC program tool change command (M6 T%1) against configured magazines. Check MD 31010 ff. (ToolMagazineType) to confirm magazine type is set to 1 (carousel) or 2 (chain) and matches physical hardware.
3
If magazine is missing, add it via Diagnostics > NCK > ToolMagazine menu. Configure magazine capacity (MD 31020), tool pocket mapping (MD 31030), and enable status bit via MD 31050 (ToolMagazineActive).
4
Execute POWER ON cycle (warm restart) to reload machine data into NCK. Verify alarm clears when re-attempting tool change with corrected magazine reference.

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