S7414 bus fault when running the plant .

In the 5 year running plant now we have a issue: when we are running the plant some groups stops suddenly i suspect that it due failure of communication. in my program i used OB85, OB86, OB87, OB122.

Diagnostic buffer of module CPU 414-2 DP

Order No./ Description Component Version
6ES7 414-2XG04-0AB0 Hardware 2
- - - Firmware V 4.1.0

Rack: 0
Slot: 2


Event 1 of 120: Event ID 16# 38C4
Distributed I/Os: station return
Address of the affected DP slave: station number: 27
DP master system ID: 1
Log. base address of the DP slave: Input address: 8164
Log. base address of the DP master: 8191
Requested OB: Rack failure OB (OB86)
Priority class: 25
External error, Outgoing event
07:10:53:582 pm 09/06/12


Event 2 of 120: Event ID 16# 39B2
I/O access error when transferring the process image to the output modules
P area, word access, access address: 36
process image partition no.: 0
not user relevant(Z1): 2943
Requested OB: Program execution error OB (OB85)
Priority class: 25
External error, Incoming event
07:10:53:566 pm 09/06/12


Event 3 of 120: Event ID 16# 39B2
I/O access error when transferring the process image to the output modules
P area, word access, access address: 36
process image partition no.: 0
not user relevant(Z1): 2943
Requested OB: Program execution error OB (OB85)
Priority class: 25