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Enter Diagnostics menu (Machine > Diagnostics > Alarms) and check NCK memory utilization via Service > System Information > Memory Statistics to quantify free DRAM percentage.

Navigate to Parameters > MD 30310 (max temporary files) and MD 32000 (trace buffer). Reduce MD 32000 from default 10MB to 2-4MB if diagnostics not actively required. Verify MD 20100 alarm buffer depth is ≤500 entries.

Reducing trace buffer may limit post-mortem diagnostics; document baseline values before adjustment.

Perform NCK DRAM reset via HMI: Machine > Maintenance > Clear Temporary Files, or issue FANUC-equivalent G-code command to purge .TMP directory. Then cycle power and retest program load.

If issue persists, check SD 55000 (NCK memory partition size). Verify allocation reflects actual hardware (e.g., SD 55000 = 64MB for 840D with 128MB DRAM). Consult machine builder OEM documentation for correct partition ratio.

Access NCK file browser (HMI: File > NC Programs > Internal Memory) and identify largest .MPF or .SPF files currently resident. Total cumulative size should not exceed 50% of available NCK DRAM (check via Service > System Information).

Delete inactive or backup program copies from internal memory; retain only active production programs. Use HMI delete function or command 'DEL prog_name' via MDI to free DRAM blocks immediately.

Verify programs are archived to external storage (CompactFlash/USB) before deletion to prevent data loss.

Review MD 30305 (maximum single program size, default 8MB) and MD 30306 (maximum total program memory). If set >available DRAM, reduce to 4MB per program and 20MB total. Recompile and reload part programs to verify they fit constraints.

Implement program segmentation strategy: split large multi-operation programs into smaller sub-programs (operations A, B, C as separate .MPF files). Use program call hierarchy (CALL 'subprog') to maintain production flow while reducing instantaneous DRAM footprint.

Run NCK built-in memory diagnostic: Access Service > Diagnostics > Hardware Tests > Memory Test (or reboot with diagnostic mode enabled). Confirm no uncorrectable error codes (UE) reported. Note any correctable error (CE) count exceeding 10 per hour.

Memory test will halt NC execution; schedule during maintenance window.

Verify SD 55000 and SD 55001 match physical hardware installed. Standard 840D configurations: SD 55000 = 0x2000000 (32MB start), SD 55001 = 0x4000000 (end address for 64MB total). Cross-reference machine nameplate or commissioning records. If discrepancy found, correct via offline parameter backup/restore or contact Siemens service.

Incorrect address parameters will cause memory access violations and potential data corruption; do not guess values.