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Heidenhain Controller
Communication · Intermediate · 30-120 minutes
HEIDENHAIN 303-0009 - Cyclic parent-child relationship
HEIDENHAIN alarm 303-0009 occurs when OPC UA configuration creates circular parent-child relationships between CfgOpcUaObject and CfgOpcUaPlcVar entities. This prevents proper node creation in the OPC UA server structure within the TNC control system.
303-0009
HEIDENHAIN 303-0009 - Cyclic parent-child relationship
Cyclic parent-child relationship
A PLC configuration or communication error has been detected. This affects the interaction between the control and the PLC system.
Root Cause Summary
HEIDENHAIN alarm 303-0009 occurs when OPC UA configuration creates circular parent-child relationships between CfgOpcUaObject and CfgOpcUaPlcVar entities. This prevents proper node creation in the OPC UA server structure within the TNC control system.
Safety
- Refer to Heidenhain service manual
- Ensure qualified technician performs repairs
Causes and Fixes
- 1
Access OPC UA Configuration
Navigate to MOD function → Communication → OPC UA Server → Node Configuration to examine the current OPC UA structure.
Use the tree view to visualize parent-child relationships more clearly
- 2
Identify Circular References
Check the parentNode attributes in CfgOpcUaObject entries for the keys mentioned in the alarm message to locate the circular dependency.
Document current configuration before making changes
- 3
Break Circular Chain
Modify one of the parentNode references to point to a different valid parent or set to root level to eliminate the circular relationship.
Start by moving the lowest-level object in the hierarchy to break the chain
- 4
Restart OPC UA Service
Restart the OPC UA server service through MOD → Communication → OPC UA Server → Service Control to apply changes.
This will temporarily disconnect OPC UA clients
Call a technician if:
- ·Configuration file corruption cannot be resolved
- ·Multiple OPC UA alarms persist after fixes
- ·Critical production OPC UA communication required
Prevention
- Regular backup of OPC UA configurations
- Validate configuration changes before applying
- Document parent-child relationships when creating complex OPC UA structures
- Test OPC UA changes in non-production environment first
Common Mistakes
- Not checking existing parent relationships before adding new nodes
- Copying configuration blocks without updating parent references
- Ignoring XML validation warnings
- Making changes without proper backup
Seeing Multiple Alarms?
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Always verify with your machine manual or a certified technician before performing service procedures.