Changing Connection WINCC Flexible 2008

RTA · May 6, 2010

I use WINCC Flexible 2008 with 2 PLC CPU 315-DP in a software redundacy configuration. I can configure 2 Connection for 2 CPUs but my tag can address only one connection at a time. How is it possible to maintain the connection if other CPU becomes master. If all my tag address connection1 what happens when connection1 fails and connection2 takes over. how could i solve this problem

Regards
RTA

ELake20 · May 6, 2010

You could do it sorta how the guys who do 400-H systems handle the change connection function.

PLC_1 is a connection, PLC_2 is a connection and the tags and everything in WinCC reference a separate connection named PLC_Changer or something. My biggest problem I've found in doing this is that you lose your ability to do symbols in WinCC.

CharlesM · May 6, 2010

Multiplexed tags perhaps?

http://support.automation.siemens.com/WW/view/en/21808321

http://support.automation.siemens.com/WW/view/en/21807422

JesperMP · May 6, 2010

It is all in this FAQ:
http://support.automation.siemens.com/WW/view/en/23842653
It describes automatic switchover.

RTA · May 11, 2010

Thanks All,
I will try out, but does FB523 supported by 315 CPUs

Regards
RTA

rohan tandon · May 11, 2010

You dont have to use FB523 when using software redundancy. You can use the status word to know which station (A or B) is the master. The status word is DBW8 of the Instance db for FB101.
If the instance DB for FB101 is DB101 then the bit DB101.DBX9.0 is TRUE when the station is master.
You can configure the PLC connection tag to change connection when this tag is TRUE as in the example on the siemens support Forum.

RTA · May 12, 2010

Thanks Rohan

The point here is the tag can have only one connection , so as long as A is master the tag communicates to connection1 but when when B becomes master the tag losses its communication as A goes to standby

Regards
RTA

rohan tandon · May 13, 2010

RTA,

I think you missed the point, there are three connections say CPU A, CPU B and CPUAB in your WinCC Flex project. All the tags are connected to CPU AB which is a dummy.

You utilise the 'Change connection' function to switch the connection of CPU AB to the master CPU which maybe CPU A or CPU B.

The status words are monitored by two tags to trigger the 'Change connections' function. The FAQ illustrates this with an example for S7 400H.

RTA · May 27, 2010

Thanks all,

I have tried as per the link mentioned by jesper.

I have uses the limit to invoke the change connection function
but the address change does not take place

I also tried with db5.dbx9.5 redundancy link failure and db5.dbx9.0

both are not able to change the connection to the current active CPU

What is that i am missing

Thanks for all ur help

rohan tandon · May 27, 2010

Have you set the acquistion mode for the tags to 'Cyclic Continous' instead of 'Cyclic on use'?

I can send you a small program where this function is used if you send me your email id as PM.

RTA · Jun 3, 2010

Thanks Rohan for Ur kind support
I could take care of the changeover by the method mentioned in the FAQ with a little modification
I use 2 CPUs with address 2 and 3 , when monitoring the db5.dbb9 of the CPUs i could find that CPU with the address 2 was active the values of DB5.DBB9 was 5 and 10 and when CPU with address 3 was active DB5.DBB9 was 6 and 9 so played with limits of the tag
Now there is no problem, the changeover works very fine.

Once again i thank u for your kind support
Keep the good work going.

Regards
RTA

Changing Connection WINCC Flexible 2008

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