Code 27220: PROFIsafe: Number of NCK F modules (%1) <> Number of S7 F modules (%2)
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical PROFIsafe: Number of NCK F modules (%1) <> Number of S7 F modules (%2) 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 = Number of parameterized NCK F modules %2 = Number of parameterized S7 F modules Definitions: The number of F modules parameterized via the NCK machine data $MN_PROFISAFE_IN/OUT_ADDRESS is: - Greater than the number of PROFIBUS slaves in the S7 PROFIBUS configuration. - Smaller than the number of F modules in the S7 PROFIBUS configuration, - greater than the number of F modules kn own in the S7 PROFIBUS configuration. If alarm parameter %2 = 0, then none of the configured F modules were found in the S7 PROFIBUS configuration. In most cases, the reason for the alarm is an error in the parameterization of the PROFIsafe master address. Reaction: Mode group not ready. Channel not ready. NC Start disable in this channel. Interface signals are set. Alarm display. NC Stop on alarm. Remedy: Check the F parameterization in MD $MN_PROFISAFE_IN/OUT_ADDRESS. Check the F configuration in the S7 PROFIBUS configuration. Check the parameterized PROFIsafe master address in MD $MN_PROFISAFE_MASTER_ADDRESS and in the S7 PROFIBUS configuration. Program Continuation: Switch control OFF - ON.
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 27220 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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