27241

Access Diagnostics > System Information on the 840D operator panel. Document the exact NCK firmware version and PLC firmware version displayed.

Cross-reference both versions against the compatibility matrix in the SINUMERIK 840D commissioning documentation. Verify that PROFIsafe DP M protocol versions are identical across NCK and PLC.

Do not proceed with machine operation until versions match.

If versions mismatch, perform a coordinated firmware update: update the PLC firmware first via SIMATIC S7 engineering tools, then update the NCK using ShopMill/ShopTurn or SINUMERIK Operate. Ensure both updates are from the same software release package.

Power cycle the 840D control and monitor the initialization log in Diagnostics > Alarms to confirm alarm 27241 no longer appears.

In SINUMERIK Operate, navigate to Machine > Parameters and search for MD18040 (Safety DP Configuration). Verify the PROFIsafe version parameter value matches the PLC safety library version.

Access the PLC program via SIMATIC S7 (if available) and verify the safety communication FB (Function Block) instances are using the correct PROFIsafe library version. Check the instance data blocks for consistency with NCK settings.

If parameter mismatch is detected, reset MD18040 to factory defaults and reconfigure PROFIsafe safety communication according to the machine builder's commissioning parameters document.

Resetting safety parameters requires machine builder approval and re-validation of safety functions.

Reboot the 840D control and observe the initialization sequence in Diagnostics > Messages to confirm alarm 27241 clears.

In SINUMERIK Operate, navigate to Machine > Parameters and verify MD18050 (F-channel Enable Flag) is set to 1 (enabled). Confirm this matches the PLC safety configuration.

Check the PROFIBUS/PROFINET network diagnostics in Diagnostics > Communication to ensure DP M slaves are recognized and the safety data exchange is listed as 'Waiting for Handshake'.

Verify that PLC cycle time and NCK real-time task synchronization are properly configured for F-channel communication. Review Diagnostics > Timing to confirm NCK and PLC cycle alignment is within specification (typically ≤10ms drift).

Power cycle the control and monitor Diagnostics > System Status during startup. If alarm 27241 persists, escalate to Siemens support with diagnostic snapshot (via Service > Export Diagnostic Data).