Translation from the Rusian text (thanks to Google Translate):

Alexlaa

Есть 2 контроллера с 7-1200. Я соединяю их с PUT / GET или TSEND / TRCV, и он работает. Но есть задача - подключить 12 контроллеров s7-1200 в одной сети, и необходимо, чтобы все видели каждый. Как это сделать? 

There are 2 controllers with 7-1200. I connect them with PUT / GET or TSEND / TRCV, and it works. But there is a task - to connect 12 controllers s7-1200 in one network, and it is necessary that everyone saw each. How to do it?

The following document covers your question, especially in chapter 6.:

CPU-CPU communications with Simatic controllers

https://support.industry.siemens.com/cs/ww/en/view/78028908

You are trying to create communications between CPUs in different central stations, which means in every CPU you must generate connections to all other CPUs, whether unspecified (for GET/PUT), specified (for AG_Send/AG_Recv comm. blocks for example), or through TConn instructions for TCP/IP. You must ensure that the allocation of connections remains whithin the CPU's limitations.

You have to do this 12 times (in every CPU you must create connections to the other 11 CPUs) and program data exchanges between the main CPU and the 11 partner CPUs.

Hope this helps,

Daniel Chartier

I wrote in English. But the translator himself online translated into Russian and I did not see it. Sorry ) 

On the topic:

"You have to do this 12 times (in every CPU you must create connections to the other 11 CPUs) and program data exchanges between the main CPU and the 11 partner CPUs." 

I  read that only 8 connections of one CPU are possible. This is not true ?

Hello Alex,

You are correct. The S7-1200 is limited in the communication resources. See the attached picture. There are more to know.

PUT and GET uses from the "S7 communication" resources. Example between PLC1 & PLC2:
- x1 PUT and x1 GET on PLC1 only
- use 2 of 8 resources for PLC1
- use 0 of 8 resources for PLC2.

TCP communication uses "Open user communication". Example between PLC1 & PLC2:
- x1 SEND and x1 RECEIVE, use 2 of 8 resources for PLC1
- x1 RECEIVE and x1 SEND, use 2 of 8 resources for PLC2
- BUT this is for a dual channel configuration!

It is possible for TCP communication to share 1 channel between both SEND and RECEIVE tasks between PLC1 and PLC2. The example above now becomes:
- x1 SEND and x1 RECEIVE making turns, use 1 of 8 resources for PLC1
- x1 RECEIVE and x1 SEND making turns, use 1 of 8 resources for PLC2
- This is for a single channel configuration!

A good example for the single channel configuration is given by Siemens as an application example: https://support.industry.siemens.com/cs/document/109747710/

TCP communication can be used for more PLCs than the 8 resources. But for this, the partners must make turns to talk to each other:
- establish communication from PLC1 to PLC2.
- PLC1 sends data to PLC2; PLC1 asks PLC2 to send data back.
- PLC1 receives data from PLC2.
- PLC1 disconnects from PLC2.
- establish communication from PLC1 to PLC3.
- PLC1 sends data to PLC3; PLC1 asks PLC3 to send data back.
- PLC1 receives data from PLC3.
- PLC1 disconnects from PLC3.
- .....

Another idea is to use ModbusTCP which is designed to have one PLC talk to several others.

Depending on how critical the communication is, it is possible to have one PLC talk to many PLCs. Some design work will have to be made to make it happen.

Regards.

Hello Alexlaa

 you also can try to use a "Master PLC" like a small S71500 PLC. Then you can connect all the S71200 to the Master and if there is a Communication Issue then the PLC can route the Information.

Bye Murof