BECKHOFF EL6930 - Manual (Page 51)

Operation
EL6930 49
The F-parameters can be adjusted by double-clicking on the module.
4.3.3.1 F_Check_SeqNr
Valid only for PROFIsafe version 1. With this you can set whether or not the SeqNr is included in the CRC
calculation of the PROFIsafe telegram (default is No Check).
4.3.3.2 F_SIL
Specification of the SIL level; the EL6930 always has SIL3.