Hello Expert,

Here in Bangladesh we are running 15 MW gas plant. Recently we observed one problem in CPU-315 2 DP. CPU-315 incorporate with some input/output cards and one Communication Processor. Our problem is some times CPU 315 goes to stop mode and SF enable. Its occurred after one month or sometimes after 2-3 days. 

can anybody figure out the real cause of this problem?

For more Help go Online and Open diagnosis Buffer Print screen and Attach here.....

Your case is because you cycle more than it sets in your CPU...

Hello,

Thanks for your replay. Pls see the attach diagnostics buffer.This diagnostics buffer is not taken on same time which i am described before. I can not attach here the diagnostics buffer at the same time of our problem date because that time i was not present at our plant.

I also notice MMC of cpu used 88% of memory. Is it caused the problem? 

Hi

I/O access error occurs when you use an invalid or nonexistant address in your PLC program (especially analog address). Cross check the addresses used in your hardware configuration and program and try to find out if there is any mismatch. That should solve the issue provided the module is healthy.

Regards

Mark

hi jamansspl,

Diagnostic

Event 1 of 10:  Event ID 16# 38C4

Distributed I/Os: station return

Address of the affected DP slave: station number:    8

DP master system ID:      1

Log. base address of the DP slave: Input address:  1022

Log. base address of the DP master:   1023

Requested OB: Rack failure OB (OB86)

Priority class: 26

External error, Outgoing event

02:48:41.998 PM  04/01/2016

(Coding: 16# 38C4  1A56  C054  03FF  03FE  0108)

I guess this is/was the root of your Problem.

DP-Slave No.8 was not reachable. So the CPU could not write to the projected adresses, what was causing the IO-access-errors.

Maybe there is a problem on the Profibus.

But there is no change to Stop in the Diagnosic-Buffer. 

Check if you can expand the Diagnosic-buffer-entries in the proberties of the CPU.

regards,

Apparently, your hardware configuration is a CPU connected to some Remote I/Os through Profibus. Each Interface module has a Profibus address.

It seems that the rack of remote I/Os that has an Interface module with address number 8 is the cause of the problem. It has one or more analog inputs that could not be read at runtime, so the CPU went into stop mode.

You have to check the Profibus cables and bus connectors as well as check the analog modules and their front connectors are tightly secured. It also might be a vibration problem that cause some cables to come out of contact. Retighten everything.

Thanks Everyone for assist me to figure out the problems. i will update the status after check profibus and its connector health. Due to the problem i already change the cable and connector a long day ago but problem still exit. i will cross check the cable and connector again and update you all soon.

Thanks,

jaman.

Hello 

I see you have Master-Slave communication ,,,as I understand you case you did not use OB 86 

you can see the attached file I hope it will help you