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MPI connection with Y cable

Thread Starter: rkosir   Started: 5/29/2008 11:50 AM   Replies: 4

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  5/29/2008, 11:50 AM
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Greetings,

i have searched the internet for possible solutions but hav enot found one for my problem.

We would like to connect S7-300 via MPI cable to 2 TP177A panels and a PC(MPI-USB converter).

Is this connection even possible or would we have to use the profibus instead of the MPI connection?

Any answers and suggestions will be greatly appreciated.
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  5/29/2008, 12:22 PM
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Hello krusi;

There is an easy way to connect multiple MPI partners together, that is using Profibus-DP cable and connectors. Simply daisy-chain the MPI ports of the PLC and HMI units with these. Make sure that all units have a distinct MPI address, of course.
When you want to connect you PC cable, you should make sure the Profibus connector that you install on the PLC has a "piggy-back" connector, that is a sencondary female DB9 on the back of  the connector where you can plug the male DB9 of the PC-Adapter USB cable; the PLC port provides power for the Adapter circuits (although there is an optional power supply you can buy for this, it is easier if you plug directly on the PLC port).
The Siemens Profibus connectors that come without a piggyback connector have a part number like 6ES7972-0BA50-0XA0; the same model with piggyback connector is 6ES7972-0BB50-0XA0.

Hope this helps,
Daniel Chartier
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  6/3/2008, 9:40 AM
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That was helpful, but it seems that our needs have changed.

We need to have PLC connected to 2 touch panels via MPI cable, profibus must not be used as there will be another configuration that needs full bandwidth of profibus to themself.

So,is it possible to use only mpi cable to connect the TP and possibly a PC for configurations? And if so,what kind of cable is needed?

Thanks
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  6/3/2008, 11:01 AM
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Hello rkosir;
If you want to use MPi to connect your PLC with multiple units, use Profibus cable and connectors on the MPI interface of your PLC. MPI is RS-485 based, as Profibus, and the same physical layer will support both.
You can use the Profibus-DP interface (also with Profibus cable and connectors) for your Profibus network in parallel with your MPI network.

The first pages of the attached document show the use of Profibus cables for MPI networking.
Simply make sure the Profibus connectorr you select for use on the PLC MPI interface has a piccy-back connector that you can use to plug your PC Adapter cable.
Hope this helps,
Daniel Chartier

Attachment: CommunicationBook_MPIPart_e.pdf  (222 Downloads)

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  6/3/2008, 12:57 PM
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Oh,i think i got it now,and it seems we have established some connections via MPI ports,
thank you for your help,

regards,
Rok
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