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Siemens SINUMERIK Controller
Parameter · Intermediate · 30-120 minutes
Siemens 4260 - Machine data illegal
Alarm 4260 occurs when a cam pair is selected in the part program without being activated in the machine data parameter MD $MN_SW_ASSIGN_TAB, or when multiple conflicting cam pairs are simultaneously selected. This violation of the cam pair assignment configuration prevents the NCK from executing the requested synchronized motion profile.
4260
Siemens 4260 - Machine data illegal
Machine data illegal
The selected cam pair was not activated by MD10450 $MN_SW_CAM_ASSIGN_TAB, or several cam pairs were selected Control reaction: Mode group not ready. NC Start disable in this channel. Interface signals are set. Alarm display. NC Stop on alarm.
Root Cause Summary
Alarm 4260 occurs when a cam pair is selected in the part program without being activated in the machine data parameter MD $MN_SW_ASSIGN_TAB, or when multiple conflicting cam pairs are simultaneously selected. This violation of the cam pair assignment configuration prevents the NCK from executing the requested synchronized motion profile.
Safety
- Only qualified personnel should diagnose and clear control alarms; follow the machine builder's safety procedures and lockout/tagout where hardware work is required.
Causes and Fixes
- 1
Access Siemens HMI menu: Diagnostics > Machine Data > MD $MN_SW_ASSIGN_TAB. Verify the cam pair index referenced in the active NC program is listed in this table.
- 2
Cross-reference the part program CTAB/CTAN command with the cam pair number. Document the cam pair ID that is being selected (e.g., CTAB(1,2) selects axis 1, cam table 2).
- 3
If the cam pair is missing, add it to MD $MN_SW_ASSIGN_TAB via HMI or Siemens NCK configuration tool. Ensure the table entry matches the part program reference exactly.
Backup machine data before modification. Verify cam table data is loaded in MD $MN_CTAB_ASSIGN before activating.
- 4
Perform a complete NCK restart (warm reset via HMI menu: System > Startup > Warm Reset) to commit MD changes to the interpolator kernel.
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