Code 27255: PROFIsafe: F module %1, general error
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical PROFIsafe: F module %1, general error 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 = PROFIsafe address Definitions: The specified PROFIsafe module signals an error. A mo re exact specification of the error's cause cannot be made without further assistance. This alarm is triggered for al l types of PROFIsafe slaves. Reaction: Mode group not ready. NC Start disable in this channel. Interface signals are set. Alarm display. NC Stop on alarm. Trigger a STOP D/E (settable via MD $MN_SPL_STO P_MODE) on all axes with safety functionality. Remedy: Check wiring. Program Continuation: Clear alarm with the RESET key. Restart part program
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 27255 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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