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Heidenhain Controller
Communication · Intermediate · 30-120 minutes
Heidenhain 125-011F - Connection setup to DNC not possible
This alarm is triggered when the TNC's DNC communication stack cannot complete the initialization handshake with external DNC software or hardware. The root cause is typically a mismatch in communication parameters, incorrect network configuration, or physical interface problems preventing proper protocol negotiation between the TNC and DNC client.
125-011F
Heidenhain 125-011F - Connection setup to DNC not possible
Connection setup to DNC not possible
Alarm 125-011F indicates the TNC control cannot establish a connection to the DNC (Distributed Numerical Control) communication interface. This occurs when attempting to use DNC remote control functions for program transfer, remote operation, or external data communication and the connection handshake fails.
Root Cause Summary
This alarm is triggered when the TNC's DNC communication stack cannot complete the initialization handshake with external DNC software or hardware. The root cause is typically a mismatch in communication parameters, incorrect network configuration, or physical interface problems preventing proper protocol negotiation between the TNC and DNC client.
Safety
- Refer to Heidenhain service manual
- Ensure qualified technician performs repairs
Causes and Fixes
- 1
Access DNC Configuration
Press MOD key, navigate to DNC Settings (or Communication Settings depending on TNC version). Note current interface selection (V24/RS232, RS422, or Ethernet).
On iTNC 530 and TNC 620/640, DNC settings may be password-protected. Default service password is often documented in machine manufacturer's service manual.
- 2
Verify Serial Interface Parameters
If using RS-232/422: Set Baud Rate to match DNC client (typically 115200 or 19200), Protocol to match client (LSV2, Standard, or machine-specific), Parity to Even or None, Data Bits to 8, Stop Bits to 1. Record all settings.
LSV2 protocol is standard for modern Heidenhain DNC communication. Older systems may use protocol setting 'Standard' with specific baud rates.
- 3
Check Machine Parameters
Access machine parameter list, review MP133.0 through MP133.3 (interface assignment), MP135.x (protocol configuration). Compare values against machine documentation or contact machine builder for correct settings.
Changing machine parameters incorrectly can affect other control functions. Document original values before making changes.
- 4
Verify Ethernet DNC Settings
If using Ethernet DNC: In MOD > Network Settings, verify TNC IP Address, Subnet Mask, and Gateway are correct for your network. Confirm DNC Server IP address is reachable and port 19000 (LSV2) is configured.
Use the TNC's built-in PING function (MOD > System Information > Network) to test connectivity to the DNC server before attempting connection.
Call a technician if:
- ·Network infrastructure changes required
- ·TNC software update needed
- ·Persistent issues after all troubleshooting steps
Prevention
- Regularly test DNC connectivity
- Keep network cables secured and protected
- Maintain current TNC software versions
- Document network configuration changes
Common Mistakes
- Forgetting to restart DNC service after parameter changes
- Mixing up IP addresses in network configuration
- Not checking both TNC and server-side settings
- Ignoring physical connection status indicators
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Always verify with your machine manual or a certified technician before performing service procedures.