I don't know if you can use them together, but both will need their own adapter card.
I don't know if you can use them together, but both will need their own adapter card.
Thanks for info, it's at least something 
Why do you need to use both? Use a master like PLC to deliver both datas in one protocol
Why do you need to use both? Use a master like PLC to deliver both datas in one protocol
The application was made some years ago, and all the ins/outs are already occupied - many data transfer. Somebody has made the application and difficult to touch it without the proper source code from the PLC side (Siemens). Right now a customer wants to make some changes (especially adding functionalities) and we need to add around 10-12 bytes (ins and outs). So when all available data using Profibus is occupied, we thought about adding next interface eg. Profinet, because it's the easiest from Siemens PLC side.
Both slaves - Profibus is already there, but second one too, because PLC will deliver the data from HMI.
Of course we also could use physical I/Os but wires, wires and other 1000 wires... keep us far away from that thought
Okay, i know it is hard to touch, but you can add new networks in your plc program that will transfer your profibus (input) data into profinet output
I mean if plc already sends information trough profinet, you can add new labels of information that you got from profibus (connected to plc) to send it through the same cable. You don't have to change source code but only profinet code module (and add some logics for using (and maybe converting if needed) profibus data).
Did I articulate clearly?
Tell me if you succeded
We misunderstood each other, so maybe I was not clear enough
In that project I olny have Profibus between PLC and robot, robot is slave on the network. All available data transferred via Profibus is already occupied. That's why we thinkl of ADDING the next comunication protocol eg. Profinet. So right now no data is transferred via Profinet, because it's not there.
And finally the question is whether it'll work together with Profibus, if we add it.
Hope right now it's clear
It was clear, i just mismatched profibus with profinet. I knew your question but i didn't got answer so I proposed an another solve to this problem, in which you don't have to buy any modules to robot.
I understood that you use full capacity of profibus and you don't have space for another data, right?
I understood that you use full capacity of profibus and you don't have space for another data, right?
Exactly, Profibus full capacity already used 
One more idea come to my mind - maybe the best would be Modbus - no hardware needed, only software to buy from robot side. I could use the ethernet port on the main board
