Dear experts,

is there any difference in programming syle of a normal s7 400 PLC and a s7-400FH PLC? My idea of fail safe PLC is that we use CFC to convert the fails safe IOs into normal IOs and then we program as usual in FB, FC OBs etc in ladder or STL. Will this be considered as SIL-3 or should we program the whole in CFC itself? An old backup i have has used F-LAD, F-FBD etc in it, how can i use them?

Thanks in advance.

Hi Stuxnet90,

 Entry should be in  STEP 7 Additional Software conference.

For F datatypes, u should use CFC. For standard data types, STL/LAD etc. is permitted. 

Hello Sachinpatke,
thank you for your reply.

//Entry should be inSTEP 7 Additional Softwareconference.// sorry i didn't knew that. how can i move this to that page?

//For F datatypes, u should use CFC. For standard data types, STL/LAD etc. is permitted.// So my assumption is correct, we only need CFC to convert F data type to normal data type.

But where is this F-LAD, F-FB all used?

Hi Stuxnet90,

F_LAD or F-FB are used in distributed safety. It is used in machine or automotive automation.