诊断缓冲区显示如下信息，帮忙看看啥意思，怎么解决？
1.I/O access error when updating the process image input table entering state
P area word access,access address 50(或42等等，每次不一样）
process image partion no:0
not user relevant (z1):2942(有时2943）
requested ob:program execution error OB(OB85)
priority class:25
external error,incoming event

2.Distributed I/O s:station return
Address of the affected DP slave:station number :13
DP master system ID:2
Log.base address of the DP slave:input address:8168(或8172，8174等）
Log.base address of the DP master:8191
requested OB:failure OB(OB86)
priority class:25
External error,outgoing event