27204

Navigate to Diagnostics > Machine Data > $MN_SAFE_IN_HW_ASSIGN in HMI and document all parameterized $A_INSE entries and their index positions.

Cross-reference each $A_INSE entry against MD $MN_PROFISAFE_IN_ASSIGN in the Safety PLC configuration to identify redundant assignments.

The alarm message parameters %1[%2] and %3[%4] indicate the conflicting MD numbers and indices—note these for reconciliation.

Remove the duplicate $A_INSE assignment from either DMP or PROFIsafe configuration, but NOT both. Typically, retain assignment in PROFIsafe module only for safety-critical inputs.

Reload all Safety PLC code (F5 in STEP 7 Safety), re-download to the 840D, and verify alarm clears on next system startup.

Open Safety PLC editor and search all PROFIsafe module declarations in the Safety program for instances referencing the same input address (check FB instance parameters).

Review the project architecture: determine if multiple modules should legitimately monitor the same input or if this is an unintended copy-paste configuration error.

Remove the input assignment from all but one PROFIsafe module instance. If distributed monitoring is required, use a single module output as a branch source to other modules instead.

Recompile Safety code, verify MD $MN_PROFISAFE_IN_ASSIGN shows unique assignments per module, download, and restart the control.

Access Diagnostics > Machine Data and navigate to both $MN_SAFE_IN_HW_ASSIGN and $MN_PROFISAFE_IN_ASSIGN; export or screenshot all indices and values.

In STEP 7 Safety project, generate a fresh Safety PLC compilation with all modules and download the complete source again using 'Generate and Download' (not incremental update).

Set MD $MN_SAFE_INIT_CLEAN = 1 temporarily to force Safety module re-initialization and clear cached assignment data.

Power-cycle the 840D control fully (remove 24VDC supply for 10 seconds) to clear NCK volatile memory and force fresh parameterization load from persistent storage.

Re-enter the system in T-mode, verify Machine Data shows only single assignments per input, and confirm alarm 27204 does not reappear.