Code 4621: Invalid handwheel input for handwheel %1
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical Invalid handwheel input for handwheel %1 alarm. Immediate attention from a qualified operator or maintenance technician is required to prevent secondary damage to the equipment or spoiled parts during the manufacturing cycle. Always ensure standard safety and LOTO procedures are followed before accessing electrical cabinets.
Official Troubleshooting Steps
Parameters: %1 = Handwheel input Definitions: For SINUMERIK 802D only: The handwheel input for handwheel %1 request ed through MD11352 $MN_HANDWHEEL_INPUT is not available for 802D systems. A maximum of 2 handwheels can be directly linked to 802D system. Reaction: Interface signals are set. Alarm display. Remedy: Configure MD11352 $MN_HANDWHEEL_INPUT for a valid input for the corresponding handwheel Program Continuation: Switch control OFF - ON. Diagnostics Manual (DAsl), 03/2009
Source: SINUMERIK 840D sl / 840Di sl / SINAMICS S120 Diagnostics Manual (DAsl, 03/2009)
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Siemens SINUMERIK 840D CNC Alarms
Siemens controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code 4621 on the SINUMERIK 840D CNC identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Siemens's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 4014 Siemens SINUMERIK 840D CNC codes.
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