I/O Access Error and OB 85 function

Dear Expert,

I ever follow training about SIMATIC S7-400 from my senior in college. In that training I know that OB 85 can prevent our CPU STOP when I/O Access Error occur.

But yesterday I found different situation in my site. My S7-400 CPU still STOP when I/O Access Error occur even there are OB 85 in the program.

What happen with OB 85? Why it can't prevent my CPU to STOP running. Or my knowledge about the function of OB 85 was wrong?I need your suggestion...

Herewith my CPU log from diagnostic buffer when problem occur , I also screenshot of my diagnostic buffer :

Event 32 of 500:  Event ID 16# 39B3

I/O access error when updating the process image input table incoming

P area, byte access, access address:    200

process image partition no.:  0

not user relevant(Z1): 2942

Requested OB: Program execution error OB (OB85)

Priority class: 25

External error, Incoming event

07:20:32.633 PM  05/18/2015

(Coding: 16# 39B3  1955  1050  2942  0000  00C8)

==================================

Event 33 of 500:  Event ID 16# 39B4

I/O access error when updating the process image output incoming

P area, byte access, access address:    200(PQW512)

process image partition no.:  0

not user relevant(Z1): 2943

Requested OB: Program execution error OB (OB85)

Priority class: 25

External error, Incoming event

07:20:32.633 PM  05/18/2015

(Coding: 16# 39B4  1955  1050  2943  0000  00C8)

===================================

Event 30 of 500:  Event ID 16# 530D

New startup information in STOP mode

Startup prevented by:

- Power on necessary

- STOP request exists

- Cold restart or warm restart necessary

Startup information:

- Time for time stamp at the last non backed up power on

- Single processor operation

Current/last startup type:

- Warm restart triggered via MPI

Permissibility of certain startup types:

- Manual startup not permitted, corrections in parameter assignment, submodule, etc. necessary

Last valid operation or setting of automatic startup type at power on:

- No startup type/following memory reset

Operating mode: STOP (internal)

Incoming event

07:20:33.485 PM  05/18/2015

(Coding: 16# 530D  FF04  C777  8041  0004  0100)

===================================

Event 31 of 500:  Event ID 16# 494D

STOP due to IO error

No relevance for user (Z1): 941a

No relevance for user (Z2): 0006 (Z3): 44ab

Previous operating mode: RUN

Requested operating mode: STOP (internal)

External error, Incoming event

07:20:33.484 PM  05/18/2015

(Coding: 16# 494D  FF84  5050  941A  0006  44AB)

Hi,

Check the hw in the main rack. Check your CPU. Upload the full buffer list. The CPU is not stoped because of the IO access error. Have a look at this thread:

PLC does not run: "STOP due to IO error"

Hi MicroMan,

Thanks for your reply.. 

If there is problem with HW card or rack similiar with this post PLC does not run : "STOP due to IO error"

so in my situation is very strange, because after the problem occur and STOP it goes to RUN again after I COLD restart it. Is this situation impossible if there are HW or rack problem?

Hi,

If You can have a failing HW element on your MAIN RACK,  and cold restart fix it, it means for me that the defective HW  have an internal issue. Soon it will not run at all.

I collected some literature to you, please have a look:

416-2DP stop caused by IO error ID 494D 

An FAQ about the similar issue on S7-300:

Why does my SIMATIC S7-300 CPU go into STOP with error 16#4548 "Stop by I/O administration"?

I hope I could help

I just want to know if you found the solution because I have the same problem.

Thanks in advance.

Hi AurinoP,

In the image shared, u selected entry no 33. Can u select entry no 31. After that press help on event button . Share the same here. 

Dear expert,

I have s7_400 , 5 racks , every rack have 5 slots .

suddenly , all AI Modules give 7FFF and DI Modules and DO Modules hold in its last status , all of this continue for 4 seconds then return back normal , it happens 6 to 7 times in houre , no fault or alarm appeared in ET200 or CPU . what is the problem pls?