Code 6441: Writing of $P_USEKT not allowed.
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical Writing of $P_USEKT not allowed. 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
Definitions: An attempt was made to write the value of $P_U SEKT. This is not possibl e since programming T= 'location number' with automatic setting of $P_USEKT is active. Reaction: Interpreter stop NC Start disable in this channel. Interface signals are set. Alarm display. Remedy: - Check how the NC is supposed to be conf igured. (See bit16 and bit22 in MD 20310 $MC_TOOL_MANAGEMENT_MASK). - Is a part program being used that is intended for an NC control without T='location number' with automatic setting of $P_USEKT? This program cannot be started on an NC control with T='location number' with automatic setting of $P_USEKT. - Either run the part program on an appropriate NC control or edit the part program. Program Continuation: Clear alarm with the Delete key or NC START. 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 6441 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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