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Heidenhain Controller
Parameter · Intermediate · 30-120 minutes
HEIDENHAIN 120-000C - Soft-key group without first element
This alarm is triggered by a structural error in the softkey menu definition system, where the control's user interface parser encounters a softkey group that lacks the mandatory first element in its definition table. This is almost always related to custom programming (cycles, PLC dialogs, or user interfaces) or corrupted system files rather than hardware faults.
120-000C
HEIDENHAIN 120-000C - Soft-key group without first element
Soft-key group without first element
A soft-key group exists in the configuration, but none of its keys is flagged as the first member. The group needs a designated starting element to function properly.
Root Cause Summary
This alarm is triggered by a structural error in the softkey menu definition system, where the control's user interface parser encounters a softkey group that lacks the mandatory first element in its definition table. This is almost always related to custom programming (cycles, PLC dialogs, or user interfaces) or corrupted system files rather than hardware faults.
Safety
- Refer to Heidenhain service manual
- Ensure qualified technician performs repairs
Causes and Fixes
- 1
Identify Recently Modified Custom Content
Navigate to TNC:\cycles\ or TNC:\table\ directories and identify any custom .H, .A, or cycle files modified near the time the alarm first appeared. Note the timestamp and file names.
Use the File Manager's detail view to sort by modification date - this quickly reveals recently changed files that may be causing the issue.
- 2
Temporarily Rename Suspect Files
Rename suspected custom dialog or cycle files by adding .BAK extension (e.g., MYCYCLE.H to MYCYCLE.H.BAK) to prevent the control from loading them. Reboot the control to test if alarm clears.
Document original file names and locations before renaming to ensure proper restoration later.
- 3
Examine Dialog Syntax
Open the suspect file in the TNC editor and verify softkey group definitions follow proper structure: BEGIN_TABLE, SK_TABLE with first element defined, proper END_TABLE closures. Each softkey group must have at least one valid entry.
Compare your dialog structure against working Heidenhain example cycles in TNC:\system\cycles\ to verify proper syntax and formatting.
- 4
Test File Restoration Incrementally
If alarm clears with files renamed, restore files one at a time, rebooting after each to isolate the specific problematic file. Edit the identified file to correct the softkey group structure.
Keep a validated backup of all custom cycles and dialogs on external media to facilitate quick restoration and comparison.
Call a technician if:
- ·If configuration changes do not resolve the alarm after multiple attempts.
- ·If hardware diagnostics indicate a memory fault or other hardware issue.
Prevention
- Always backup configuration data before making changes or performing updates.
- Train operators and technicians on proper configuration editing procedures.
- Schedule regular firmware updates to address known bugs and improve system stability.
- Implement access controls to limit who can edit critical configuration settings.
- Follow proper lockout/tagout procedures during any maintenance activities.
- Maintain current documentation of all configuration changes.
Common Mistakes
- Failing to save changes after editing the configuration, leading to persistent alarms.
- Overlooking backup restoration options, resulting in unnecessary manual reconfiguration.
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Always verify with your machine manual or a certified technician before performing service procedures.