S7-300 OB86,OB122 fault detect

Hello.We are using S7-300 Cpu.Sometimes give an error.OB86 and OB122 blocks called.OB86 Block ;

L #OB86_FLT_ID
T DB1.DBB 14
L #OB86_EV_CLASS
T DB1.DBB 15
L LB 11
T DB1.DBB 16

When I looked to DB1.

DB1.DBB14 : Byte: B#16#C4
DB1.DBB15 : Byte: B#16#38
DB1.DBB16 : Byte: B#16#5

And in OB122 Block:

L #OB122_MEM_AREA
T DB3.DBW 14
L #OB122_MEM_ADDR
T DB3.DBW 16

When I looked to DB3.

DB3.DBW14 : Int:16
DB3.DBW16 : Int: 4

is showing.And we make plc stop/run.Maschine is run and operating again.

According to these values can we fix problem.That is which module is defect?
Thanks in advance.

As far as I remember the best way is to look at the ISTACK when the fault occurs with the S7 software this will give you a little more information.

I suggest you read this.

https://support.industry.siemens.com/forum/gb/en/posts/ob86-with-s7-300/267039

Parky, thank you for your kind return. I understood the working philosophy of OB86. It shows that there is a problem with the station with the Profibus address of 5.
It shows integer 16 as #OB122_MEM_AREA, integer 4 as #OB122_MEM_ADDR. I don't understand if this address is DI or DQ module address, bit, byte, word, dword access? Thank you for any additional information.

Haven't got time to go through it but this document seems to have the information you may need, Look at pages 32 onwards it has information on the diagnostic buffers.

https://cache.industry.siemens.com/dl/files/574/1214574/att_44504/v1/SFC_e.pdf

If you have come so far as to identify DP station #5 as the culprit, then looking into the diagnostics buffer wont help any further.

You need to troubleshoot the issue by checking the hardware.
Check the cables and connectors.
Check earthing and equipotential bonding.
Swap the station #5 with another identical hardware. Does the problem disappear, remain, or follow the swapped hardware ?

Parky and jespermp thanks. I changed the profibus connector of station no.5 but the fault continues. So i replaced all profibus cables and connectors of the machine. The machine works without problems for 1 week.

Yep it's the most common problem I have come across, had a number of failures on cable or connectors (even had the termination resistor switch go open) that is used on the ends of the profibus run.

Yup, cable & connectors are the most common issue I've seen with Profibus, other than someone moving the switch "accidentally" and a pretty regular failure we saw with a Festo bus module.