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Access Siemens SINUMERIK 840D control panel and navigate to: Diagnostics > Machine Data > MD20000 (General Options). Verify that the 'Handwheel on PROFIBUS' option bit is set to '1' (enabled). If set to '0', this is the root cause.

Changing machine data requires HLI (High Level Interface) access or appropriate user permissions. Save current configuration before modifications.

If MD20000 does not contain a specific handwheel PROFIBUS bit, check handwheel-specific machine data parameters in the 3xxx range (typically MD3xxx for handwheel configuration). Verify the handwheel type is configured as 'PROFIBUS' or equivalent in the corresponding machine data entry.

After enabling the option, perform a complete NCK reset (warm start or cold start as appropriate for your machine configuration). Use: Machine > Reset or press the RESET button on the control panel.

A warm start may not fully initialize PROFIBUS handwheel functionality. If the alarm persists, perform a cold start to force full configuration reload.

Access the control panel and navigate to: Diagnostics > System Information > Software/License Information. Look for 'Handwheel on PROFIBUS' or 'PROFIBUS Handwheel' in the list of installed options. If not present, the feature is not licensed.

Contact your Siemens automation distributor or support to obtain and install the 'Handwheel on PROFIBUS' license/option package for your 840D control system. Provide your machine serial number and current software version.

License installation typically requires service engineer access and may require control restart.

After license installation, perform a cold start (full system restart) to reload the NCK with the new feature set enabled.

Verify PROFIBUS hardware is present and connected. Check the control panel for PROFIBUS module status indicators. Confirm all PROFIBUS cables are securely connected and terminated correctly (120Ω termination at both ends of the PROFIBUS line).

Access the PROFIBUS configuration tool (typically accessible via Diagnostics > Communication > PROFIBUS or through STEP 7 software). Verify that handwheel devices are listed and have valid node addresses (typically address 31 for handwheels). Check that the PROFIBUS baud rate matches hardware configuration.

PROFIBUS address conflicts or incorrect GSD configuration will prevent handwheel communication.

Perform a PROFIBUS re-initialization by navigating to: Machine > Communication > PROFIBUS > Reinitialize. Then perform an NCK reset to allow the handwheel option to be re-negotiated with the PROFIBUS network.