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Siemens SINUMERIK Controller
Safety · Intermediate · 30-120 minutes
Siemens 27221 - PROFIsafe: NCK F module MD [ ] unknown
Alarm 27221 indicates a mismatch between the F module configured in machine data (MD) and the corresponding PROFIsafe address defined in the S7 PROFIBUS configuration. The NCK cannot resolve the F module identity at the specified PROFIsafe slave address, preventing safe communication initialization.
27221
Siemens 27221 - PROFIsafe: NCK F module MD [ ] unknown
PROFIsafe: NCK F module MD
The F module parameterized in the specified machine data is unknown under this PROFIsafe address in the S7 PROFIBUS configuration Control reaction: Mode group not ready. Channel not ready. NC Start disable in this channel. Interface signals are set. Alarm display. NC Stop on alarm.
Root Cause Summary
Alarm 27221 indicates a mismatch between the F module configured in machine data (MD) and the corresponding PROFIsafe address defined in the S7 PROFIBUS configuration. The NCK cannot resolve the F module identity at the specified PROFIsafe slave address, preventing safe communication initialization.
Safety
- Only qualified personnel should diagnose and clear control alarms; follow the machine builder's safety procedures and lockout/tagout where hardware work is required.
Causes and Fixes
- 1
Access HMI Diagnostics > Machine Data menu and verify MD 30200 (F_MODULE_TYPE) and MD 30201 (F_MODULE_ADDRESS). Document the module type and PROFIBUS address specified.
- 2
Open the S7-PLCSIM or STEP 7 project in TIA Portal. Navigate to PROFIBUS master configuration and locate the slave device at the address from MD 30201. Verify the F module type matches MD 30200.
If using legacy SIMATIC S7-300, open STEP 7 Classic and check the PROFIBUS configuration under CPU > DP/Master > Slaves.
- 3
Compare the module identification (e.g., 6ES7 partner number) in the S7 configuration against the physical F module installed or the expected module type per machine data. If mismatch found, either update MD 30200/30201 or reconfigure the S7 PROFIBUS slave entry.
- 4
After correcting the configuration, perform a cold start (power-down/power-up) to force NCK reload of machine data and PROFIsafe parameter validation.
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