27205

Navigate to NCK > Machine Data > Safety Parameters in SINUMERIK HMI. Record the exact values shown in alarm message for %1, %2, %3, and %4 to identify which specific MD parameters are mismatched.

Note the parameter numbers from the alarm message; they will guide you to the exact MD locations.

Access Siemens SINUMERIK parameter documentation and cross-reference the declared signal counts in MD 37100/37101 against the actual array dimensions configured in MD 37102/37103 (or relevant safety signal configuration blocks).

Edit the machine data so that the number of signals declared matches the array size. If using 5 PROFIsafe input signals, ensure MD 37100 = 5 and MD 37102 array size = 5. Apply changes and perform a complete PLC/NCK warm restart.

Changes to PROFIsafe parameters require controller restart; do not modify while axes are in motion.

Verify the correction by checking System > Diagnostics > Safety in the HMI to confirm PROFIsafe initialization completes without alarm 27205.

In SINUMERIK, navigate to NCK > PROFINET Configuration > Safety Nodes. List all connected safety modules and document the PROFIsafe signal counts declared for each node.

Compare signal count entries across all safety nodes. The alarm message parameters %2 and %4 will point to specific node or module instances; verify consistency between the declared count and the actual GSD/configuration file for that device.

Ensure firmware versions on all safety modules match; mismatched versions can cause signal definition conflicts.

Synchronize MD parameters on all modules so PROFIsafe signal counts are identical. If using a safety controller or distributed safety architecture, use the SINUMERIK Configuration Tool (SCT) to update all modules simultaneously.

Perform a full system validation using NCK Diagnostic > Safety System Check and verify all modules report consistent signal counts before restarting the controller.

Back up the current machine data by exporting via SINUMERIK HMI: System > Machine Data > Export. Save the file and verify file integrity (check file size against previous known backups).

Use SINUMERIK's memory diagnostics (Diagnostics > System Memory > Integrity Check) to scan NCK memory for corruption. If errors are detected, note the memory range and consider a complete machine data reload from a known-good backup.

Memory corruption may require PLC memory reset; consult Siemens documentation before proceeding with memory clear operations.

Re-download the PROFIsafe machine data block using SINUMERIK HMI Machine Data > Safety Parameters > Reload from Source File. Ensure the source file matches the controller's hardware configuration (slot count, I/O module types).

After reload, perform a cold restart of the controller and monitor the NCK safety initialization log (accessible via Diagnostics > NCK > Safety Log) to confirm alarm 27205 no longer appears.