i HAVE AN ERROR Caused by a I/O access

am new to this error i request you to help me out.

the error is

_{STOP caused by I/O access error (OB not loaded or not possible, or no FRB)}

_{FC number: 1000}

_{Module address 216}

_{previously operating mode Run}

_{Requested operating mode STOP}

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Split from Simatic CPU 315-2DP (STOP caused by diagnostic interrupt (OB not loaded or not possible, or no FRB).

this error occurs when you trying to access to I/O´s that are not assigned to the CPU. 

If the CPU stops you have normally a option to go to the program-part where it happens. Even the entry in diagnositc buffer tells you it is in FC1000.

When this errors comes up the CPU tries to call the OB122. When the OB122 is not loaded the CPU goes in Stop.

hope this helps,

regards,