SFB20 Using

JesperMP · Nov 27, 2020

In Siemens software redundancy solution the CPU that is not the active one is not stopped, it is disconnected from the I/O.
For a redundancy solution, you need to exchange data about the program status so that the backup CPU can take control without having to initialize the program.

tecno44 · Nov 27, 2020

sigmadelta said:
The thing is, even if SFB20 works and you stop the CPU, there is no way to start it again unless you either turn the RUN/STOP switch to STOP then RUN, or use STEP 7 software to put the CPU back into RUN. There is no way via PLC code to make a CPU go into RUN.

Can be restarted with SFB19(START)

tecno44 · Nov 27, 2020

JesperMP said:
SFB14 and SFB15 are only supported on S7-400.

An S7-300 can respond as server to a PUT or GET from another PLC as client. There will then be no PUT or GET on the S7-300 as server.

When using PUT or GET with an S7-300 as client, you should use the FB14/FB15 from the standard library.
If you use an CP for the connection you must use FB14 or FB15 from the SIMATIC_NET_CP library.
That is, not SFB14 or SFB15.

But now I am using SFB 14 and SFB15. No problem.

tecno44 · Nov 27, 2020

JesperMP said:
Is the redundancy needed for high uptime in a production scenario ?
Or is the redundancy needed to provide a more reliable system that handles critical safety for persons, for example smoke evacuation from tunnels, electrical power supply in hospitals, etc..
If it is the latter, dont make a do-it-yourself design.

Yes, it is a project prepared for a high security and strategic structure.

tecno44 · Nov 27, 2020

JesperMP said:
In Siemens software redundancy solution the CPU that is not the active one is not stopped, it is disconnected from the I/O.
For a redundancy solution, you need to exchange data about the program status so that the backup CPU can take control without having to initialize the program.

Yes, great information. I thought about this issue as well. But I couldn't find a way to disconnect the module. Is there a function or advice you can recommend?

JesperMP · Nov 27, 2020

tecno44 said:
But now I am using SFB 14 and SFB15. No problem.

Just to satisfy my curiosity, can you post a screenshot from the call of SFB14 when online ?

tecno44 said:
Yes, it is a project prepared for a high security and strategic structure.
[..]
is there a function or advice you can recommend?

Just disconnecting a CPU is not enough.
This is a huge topic.
My best advice is to go for an S7-400H solution. The IO must be ET200M with special backplanes that support switching between two IMs in a redundant configuration.
It would also require some training.
It wont be cheap. But something that is to be used for a high security and strategic structure should not foremost be cheap.

tecno44 · Nov 27, 2020

JesperMP said:
Just to satisfy my curiosity, can you post a screenshot from the call of SFB14 when online ?

Just disconnecting a CPU is not enough.
This is a huge topic.
My best advice is to go for an S7-400H solution. The IO must be ET200M with special backplanes that support switching between two IMs in a redundant configuration.
It would also require some training.
It wont be cheap. But something that is to be used for a high security and strategic structure should not foremost be cheap.

Master, you are right when they say, but it is not possible. I believe I will handle it. I think if I change the address of the Socket with SFC71, the connection with the module will be lost? Do you have any other suggestions?
besides, nothing is impossible.
If everything is done correctly, I think it will be a nice system with s7 300

For SFB14 and SF15, I can take the screenshot when it starts Monday. You can also connect via remote desktop.

tecno44 · Nov 27, 2020

By the way, I prepared the Scada part with Sharp7 with VS C #.
Older systems were WinCC 5.1 on WindowsNT4.

JesperMP · Nov 27, 2020

tecno44 said:
I think if I change the address of the Socket with SFC71, the connection with the module will be lost?

You are losing me here.
SFC 71 is used to extract the physical location (which rack or Profibus ID or Profinet ID, and which slot) an IO Address belongs to. SFC 71 does not change anything.

Apart from that, I dont want to provide advice for something that I believe is a dangerous and wrong solution to a critical application.

drbitboy · Nov 27, 2020

sigmadelta said:
The thing is, even if SFB20 works and you stop the CPU, there is no way to start it again unless you either turn the RUN/STOP switch to STOP then RUN, or use STEP 7 software to put the CPU back into RUN. There is no way via PLC code to make a CPU go into RUN.

I dunno, how about having the first PLC drop the fish at step 7 of this contraption, and the second PLC is in place of the PC?

tecno44 · Nov 27, 2020

JesperMP said:
You are losing me here.
SFC 71 is used to extract the physical location (which rack or Profibus ID or Profinet ID, and which slot) an IO Address belongs to. SFC 71 does not change anything.

Apart from that, I dont want to provide advice for something that I believe is a dangerous and wrong solution to a critical application.

OK. I will disconnect the CPU and the Module with the idea you gave. CPUB will not be able to read or write data to other stations when CPUA is enabled.
I will transfer Data blocks from CPUA to CPUB over Profinet. When the CPUA fails, it will open its connection with the CPUB Module and send and receive data to other CPUs.
You can be helpful as an idea. Brainstorm after all.

tecno44 · Nov 27, 2020

drbitboy said:
I dunno, how about having the first PLC drop the fish at step 7 of this contraption, and the PLC is in place of the PC?

Shall we change the title?: lolis:: lolis:: lolis:

tecno44 · Nov 28, 2020

By the way, I started SFB 19-20-21.

I have processed P_PROGRAM manually into the M100. 9 BYTE.
so it works.
Thank you.

SFB20 Using

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