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Check DNC interface settings

Navigate to HMI → Commissioning → NCK → Channel → Program control and verify DNC interface parameters match external system configuration.

Document current settings before making changes for easy rollback

Verify communication parameters

Check machine data MD10700 (DNC_HANDSHAKE_TYPE) and MD10710 (DNC_PROTOCOL_TYPE) to ensure compatibility with external DNC system.

Incorrect handshake settings can cause data loss during transfer

Test with simple program

Transfer a basic G-code program via DNC to isolate whether issue is protocol-related or program-specific.

Use SINUMERIK's built-in DNC test function in diagnostics menu

Review alarm buffer timing

Check alarm buffer for related communication timeouts and verify MD10720 (DNC_TIMEOUT) values are appropriate for network conditions.

Enable data integrity checking

Activate MD10730 (DNC_CHECKSUM_ENABLE) to enable automatic checksum verification for external data transfers.

This will slow transfer slightly but prevents execution of corrupted data

Check network cable integrity

Inspect Ethernet cables for damage and verify connection stability using HMI → Diagnostics → Hardware → Network interface statistics.

Power down system before checking physical connections

Monitor transfer buffer

Check MD10740 (DNC_BUFFER_SIZE) and ensure adequate buffer allocation for external program size to prevent data overflow.

Increase buffer size incrementally - excessive allocation can impact system performance

Verify file format compatibility

Ensure external programs use proper SINUMERIK-compatible format with correct line endings and character encoding (ISO 8859-1).

Enable syntax pre-checking

Set MD10750 (EXT_PROG_SYNTAX_CHECK) = 1 to enable pre-execution syntax validation for externally received programs.

This catches syntax errors before they reach the interpreter

Review program structure

Check external program for proper program structure including program number format (%_N_filename_MPF) and main program/subroutine organization.

Incorrect program numbering can cause file system conflicts

Validate G-code compatibility

Cross-reference used G-codes with HMI → Commissioning → NCK → Language → G-code settings to ensure all commands are enabled for this system configuration.

Check coordinate system setup

Verify external program coordinate references match active work offset settings (G54-G59) and machine coordinate system configuration.

Check NCK memory utilization

Navigate to HMI → Diagnostics → NCK → Memory and monitor dynamic memory usage during external program execution attempts.

Memory usage above 85% typically indicates resource constraints

Optimize lookahead settings

Adjust MD20482 (LOOKAH_BLOCKS) to reduce lookahead depth if external programs contain complex geometry requiring excessive preprocessing.

Reducing lookahead too much can impact machining quality and feed rates

Clear program memory

Delete unused programs from NCK memory via HMI → Program Manager → NCK → Delete to free resources for external program execution.

Review system loading

Check MD10760 (MAX_EXT_PROG_SIZE) and ensure external programs don't exceed configured limits for single program execution.

Test network interface diagnostics

Run built-in network diagnostics via HMI → Diagnostics → Hardware → Network interface test to identify hardware-level communication failures.

Network tests may temporarily interrupt active connections

Check physical connections

Inspect network port LEDs for proper link and activity indication, and verify cable seating in both SINUMERIK and external system ports.

Intermittent LED activity often indicates loose connections or cable damage

Monitor error statistics

Review network error counters in diagnostics menu for CRC errors, packet loss, or timeout conditions that indicate hardware degradation.

Test with known good hardware

Temporarily connect external system via different network interface or cable to isolate hardware failure from configuration issues.

Document MAC addresses and IP settings before hardware substitution