6451

Access Siemens HMI > Diagnostic > Machine Data > search MD 20050 (Tool change type). Verify the current setting matches your machine hardware configuration.

If MD 20050 is set to automatic changer mode (value 1-5), check MD 20150 (Number of buffer positions in buffer magazine) to confirm it is populated with a value > 0. If MD 20150 = 0 or empty, this is the root cause.

Do not modify MD 20050 without verifying hardware compatibility

In NCK > Tool > Magazine configuration menu, verify that buffer magazine geometry parameters are defined: MD 20151 (Buffer magazine type), MD 20152 (Position arrangement), and MD 20153 (Magazine capacity). All must have valid values.

After correcting machine data, perform a Control > Initialize > Warm restart to reload NCK parameters. Then retry the tool change command (T-word + M6).

Warm restart will interrupt current program execution

Review the NC program at the alarm block location (%2). Confirm whether the tool change uses T-word followed by M6, or uses M6 alone. Cross-reference with the intended machine configuration.

Access Machine Data > MD 20050 and MD 20051 (Tool change type and tool change synchronization). Ensure MD 20050 value aligns with the presence of buffer magazine hardware. Value 0 = manual, values 1-5 = automatic with buffer magazine.

If the machine has a buffer magazine, set MD 20050 to the appropriate automatic mode (consult machine builder documentation for correct value). If no buffer magazine exists, modify the NC program to use manual tool change or remove M6 commands.

Changing MD 20050 may require PLC program recompilation

Perform Control > Warm restart and retest the tool change operation at the alarm block.

Access HMI > Diagnostic > PLC > Inputs/Outputs. Monitor signal group related to tool magazine (typically DB31 or machine-specific tool magazine DB). Check that tool magazine ready signal is TRUE and no fault signals are active.

In PLC > Program > Tool Magazine block (if present), verify the PLC routine is called cyclically and that initial buffer magazine parameters have been loaded. Check PLC debug mode to confirm tool magazine logic is executing without errors.

Confirm that the interface variable linking NCK tool change requests to PLC magazine control is properly mapped. Typically check MD 22150-22160 (Tool change interface parameters) to ensure correct data block and signal assignments.

Reset PLC (Control > Reset) and perform a Warm restart. If alarm 6451 persists, escalate to machine builder to verify PLC tool magazine logic is operational.

PLC reset will interrupt current operations