6610

Access Diagnostics > File Management in the 840D HMI to view current open file count on the NC card. Check the kernel log via WinNCEdit or the Service menu to identify which part programs or subroutines remain open.

Do not attempt to forcibly close files while NC is in motion; stop all axes and programs first.

Review the active part program and any active subroutines (use Siemens SINUMERIK Operate > Program > Open > check Call Stack). Verify all CALL statements have matching RETURN statements and all FOPEN operations have corresponding FCLOSE before program end.

Check parameter MD 36100 (MaxSubroutineCallDepth) via HMI Menu > Machine > Parameters > Spindle/Motion > NCK. Reduce from default if excessive nesting is detected; typical safe value is 50-100 depending on memory resources.

Changing MD 36100 requires NC cold restart (warm restart insufficient).

Perform NC cold start: Diagnostics > NC > Cold Start. This clears all file descriptors in the NCK kernel and resets the file table. Monitor for recurrence during subsequent program cycles.

Cold start deletes all buffered data; ensure program is saved externally.

Stop the NC immediately and access Diagnostics > File System > Open Files to list all files currently held open by the kernel. Identify any orphaned file handles from aborted programs.

Do not restart NC immediately; orphaned handles may persist.

Review the last executed part program in the NC Editor (Operate > Program > Open). Search for all FOPEN commands (typically in G-code subroutines or user program sections) and verify matching FCLOSE statements with identical file unit numbers. Check SD 42760 (FileOpenCount) to monitor real-time file descriptor usage.

Increase MD 36950 (FileBufferSize) from default (typically 10 KB) to 50-100 KB via Machine > Parameters > File System. This allows the NC to queue more file operations before blocking. Alternatively, reduce MD 36940 (MaxOpenFiles) limit if resources are constrained; default is usually 16-32 files.

Increasing buffer sizes consumes NC card memory; verify available space via Diagnostics > System > Memory.

Perform a controlled NC power cycle: Power off, wait 30 seconds, then power on to force file table reset at the hardware level. Verify alarm clears and no file handles remain orphaned using Diagnostics > File System after restart.

Access Diagnostics > System > Disk Usage to view NC card partition utilization. Check for /tmp or temporary working directories exceeding 80% capacity. Delete old part program backups and temporary files via the file manager if storage is constrained.

Do not delete active part programs or system directories (bin/, etc/).