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Siemens SINUMERIK Controller
Servo/Axis · Intermediate · 30-120 minutes
Siemens 840D 61728 - Channel block: Internal error: Memory space problem
Alarm 61728 indicates an NCK memory allocation failure during CYCLE950 execution on the 840D controller, typically caused by insufficient working memory (WNR), stack overflow in the NC program buffer, or corrupted cycle definition. This memory space problem prevents the CNC kernel from allocating required RAM for cycle processing, halting block execution.
61728
Siemens 840D 61728 - Channel block: Internal error: Memory space problem
Channel block: Internal error: Memory space problem
Siemens SINUMERIK alarm 61728: Channel block: Internal error: Memory space problem. This alarm indicates a fault or error condition on the SINUMERIK 840D control. Refer to the Siemens SINUMERIK alarm documentation for the complete description and remedy.
Root Cause Summary
Alarm 61728 indicates an NCK memory allocation failure during CYCLE950 execution on the 840D controller, typically caused by insufficient working memory (WNR), stack overflow in the NC program buffer, or corrupted cycle definition. This memory space problem prevents the CNC kernel from allocating required RAM for cycle processing, halting block execution.
Safety
- Refer to Siemens documentation
- Ensure qualified technician performs repairs
Causes and Fixes
- 1
Access SINUMERIK HMI → Diagnosis → Memory → NCK Memory Pool. Verify WNR usage percentage (should be <80% under normal operation). Check MD 32000 (MEMSIZE_WNR_NCK) current value in Parameter → Volatile memory.
- 2
Increase MD 32000 in 256K blocks (0x40000 bytes). Recommended minimum: 2MB for standard CYCLE950. Modify via HMI Parameter menu or SINUMERIK Operate, then execute POWER CYCLE (not warm reset).
Do not exceed 80% of total NCK RAM or PLC collision will occur.
- 3
If MD 32000 cannot be increased, reduce nesting depth in CYCLE950 sub-routine calls by reviewing /NC/DIN/CYCLE950.SRC and eliminating recursive macro invocations or deep G-code sub-program stacking.
- 4
Execute machine reset and re-run the offending part program block. Monitor MD 32000 real-time value via Siemens SINUMERIK Operate Trace function (Diagnosis → Trace → Variable Watch).
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