I have (2) L541 5/04 PLCs in the plant and up until 3 days ago they were fine. I replaced the battery in one of them and had to reload the project. When I attempted to download, it failed with errors - ERROR: FBC instruction is not valid on the currently selected processor!-> 1747-L541 5/04CPU - 16K Mem. OS401. Both of the SLCs have FBC instructions in the ladder file and have for several years. I am running linx 3.51.01 CPR 9 SR 5.1 and Logix 500 9.00.00 (CPR9). Has anyone seen this anomaly? Any help greatly appreciated!