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The communication between two S7-1200!

Thread Starter: freefly2009   Started: 12/27/2009 4:49 AM   Replies: 1

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  12/27/2009, 4:49 AM
Joined 11/29/2009
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I have two s71200 cpus (dc/dc/rly). now I want the two cpus could communicate.
Could two S7-1200 cpus communicate with an rj45 cable connecting (no switch module)?
I found two examples on the

The solution A used two cpus and a switch module csm1277, but I have no csm1277!
I made a programme and upload :
when I download the programme to the two cpus, I connect the two cpus with an rj45 cable, I found the two cpus didn't work.

=== Edited by freefly2009 @ 12/27/2009 4:50 AM [GMT ] ===

  12/27/2009, 1:14 PM
Joined 10/7/2005
Last visit: 1/29/2015
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Hello freefly2009 

The CSM1277 Ethernet switch is just a simple unmanaged 4 port Ethernet switch, any other Ethernet switch (managed or unmanaged) can be used instead of it.
If you do not have a switch available you can also directly connect the two CPU's with an Ethernet cable (which can be a direct or crossover cable, the PN port of the S7-1200 does have the so called "Auto crossover" functionality inbuilt).

Bottom line, the the "missing" CSM1277 is not your problem, so its either your program/configuration or a faulty Ethernet cable (I don't yet have Step 7 Basic and can't unfortunately verify your program).

I suggest you first get your hands on any Ethernet switch you can find so you can link teh two CPU's ADN your programmig nlaptop together to be able to test your comms setup and logic (you are locking yourself out from this at the moment if you link the two CPU's directly with an Ethernet cable).

I hope this helps and good luck 



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