Hello guys

Could you please advice about the differance between communicate between 2 CPUs using profibus if

1-Both were masters

2- one was master and the other was slave

Hello sherief;

May we ask in return what network you plan to use between the CPUs? Also what hardware can you play with for this project?

Your question is much too general, we can only help if you give us a starting description of the situation.

Hope this helps,

Daniel Chartier

It is not related to specific project.

Iam asking if I linked 2 CPUs " for example 315 dp/2pn" using integrated profibus port.

first  Master/Master........ If the IO modules attached to one cpu can be used for second cpu software

second Master/Salve........... can slave use master IO 

sherief

Iam asking if I linked 2 CPUs " for example 315 dp/2pn" using integrated profibus port.

first  Master/Master........ If the IO modules attached to one cpu can be used for second cpu software

second Master/Salve........... can slave use master IO 

 Your first scenario is easy to answer: 2 CPUs configured as Profibus-DP masters cannot be linked over  their integrated Profibus ports; you must use a CP 342-5, only a CP can handle the master-master connections and communications blocks.

If you want to read/write between 2 DP-masters using their integrated DP-ports, your only option is to insert a DP/DP coupler between the 2 Profibus networks. When commissioning the coupler, you can assign addresses from your I/O tables from one master to the other, if you want to. Remember that as a DP-slave the coupler will limit exchanges to 244 Bytes OUT/244 bytes In, as per the Profibus standard.

Look at the following document for more details: DP/DP Coupler

https://support.industry.siemens.com/cs/ww/en/view/1179382

As for the master/slave scenario, you can assign addresses to the master's I/O tables from the slave, yes. But if you explain your plan in more details, we would be better placed to discuss the issue.

Generally we do not like the I/Os of a CPU to be controlled by an outside partner, we do not like the idea of losing control of our process commands without supervision...Specially if he external commands are sent over a network that might fail without diagnosis (you would have to make sure the master takes control of the process immediately if the slave goes offline, for example).

Hope this helps,

Daniel Chartier