systems S7-400H

The main power feeder PLC switch off
1- Power OFF on the power supply (PS) of the rack that houses the CPU ( all  LED OFF the CPU,CP,PS )
2- i am Power ON Feeder PLC on the power supply of the rack that houses the CPU ( all LED ON On The PS- the LED stop from cpu and cp is on red and LED extrf cpu  and LED intf cp
3- i am stop the switch cpu after about 2 min switch ran cpu the LED ran Flash after 1 sec the LED stop the cpu is on
Please Help me

How I can found the file source of the block OB1

THANK YOU