S7-300 Rack Fault - OB86

pimpim32

Member
Join Date
Mar 2003
Posts
123
Hi everyone.

I have an S7 313C-2DP, connected to another siemens through
a DP/DP coupler.

The coupler is powered from the other plc.
When they reset their plc, mine cannot read anymore the coupler
and goes to fault, OB86 changing the plc from run to stop

What I should wrote in OB86 when the coupler comes back online
and rack is ok my plc to go back in run ( I guess a warm restart
will be beter).

Thanks for any info
Marian
 
Hello pimpim32;

Do you have OB86 loaded in the PLC? If it is present and you lose the DP slave, you should not go to SF (the fault LED will light up, but you will keep running; diagnostic values will be loaded in the Diagnostic Buffer), and you should recover comms when the slave comes back to life. You don't have to program anything in OB86, but it has to be part of the project blocks dowloaded to the CPU.
You can of course program some logic in OB86, to send data to a SCADA system when you loose a DP-slave, for example. But for its basic operation OB86 does not require any code.
Hope this helps,
Daniel Chartier
 
Thanks Daniel.

OB86 it is downloaded to CPU.

I have done a test now.
I cut Profibus communication to a drive(a slave),
SF became red, BF is blinking, CPU still run.
When I restored communication, BF stopped blinking,
SF still red and CPU goes to STOP, and I had to restart
manually.

I don't know. Maybe I should save some parameters
somewhere, but I have no ideea what.

Thanks again.
Marian
 
When the CPU goes to stop, open the diagnostics buffer online and you will get information as to why it stopped, and if there is an OB that you must load for it to continue to run.
 
So :

"Stop caused by diagnostic interrupt (OB not loaded or not
possible, or no FRB)
Breakpoint in user program, cyclic program(OB1)

Priority class :1
OB number : 1
Module Address : 162

Previous operating mode : RUN
Requested operated mode : STOP ( internal)"

This is for drive.reading/writing the drive is done in OB1

However reading/writing coupler is in some other FC.
I cannot test it now as here I do not have a coupler for the moment.

What can be?

marian
 
... it tries to post ERROR CODE to an relevant OB ... how about OB87 - Communication Error, OB84 - HW Error, OB82 - Diagnostic Interrupt ?
 
i've tried to download ob83, ob84, they weren't accepted
as associated priority class does not exist.

ob87 was accepted, but the message remained same, with
the exception of the module address which is now 350.

marian
 
The diagnostics on the CPU should give you the exact cause. As a matter of routine I download all the OB's related to diagnostics (84,5... 121,2..etc). Set a bit in the OB (any memory or DB bit). Disable the part of the software that creates problems. Do you use SFC14,15 to read write? You may reset it first manually until you find the real cause of your problem.
 
pimpim,

there can be more than one relevant entry in the diagnostics buffer.
There is probably one right before or after the one you posted with info on the relevant error OB.
 
... please let me know when you solve it Marian, i'm really starting wonder what's the problem, i my experience s300 cpu just don't stop until you declare it in error handling OB ....
 
Sorry Marius, in the end is my fault,
You've told me OB82 and OB84, put I've tried OB83 and OB84.
so normal not to work.

With OB82 downloaded everything is just OK.

In CPU messages was nothing related to OB82, however I found
about it digging for FRB to understand what it means.

Now I am keeping wondering , one should download all OB's
possible to keep out of troubles?

Thanks again everyone.
Marian
 
Good, i guess ...

Siemens vs. Human 1 : 0 :)

Just all error OB's shouldn't cause some real cpu time drain if they stay short.
 

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