Optic link - what to choose?

I had a profibus cable damage on my plant so i used the opportunity to switch to optics.
I still left with connecting PLCs so I have 3 options:

1. scalance - that is one is out cause scalance is way to expensive (1700 eur at local siemens rep)
2. cisco optic switch (like i have on one side already)
3. two westermo's ODW 710-f2 multiple profibus optic modems

I have dilemma about last two. If going to westermo's then all is on profibus and independent and nothing to change; or could i go with cisco switch and go through ethernet?
Currently, one PLC is connected to SCADA through cisco switch and office LAN as in scheme posted...

PLCs are S7 1200 (and already have Profibus module in their racks)

Stick to one interface

I'd go with a Siemens' Optical Link Module (OLM): http://www.automation.siemens.com/m...omponents/optical-networks/olm/pages/olm.aspx

hmmm... i'd thought that is the same as scalance but apparently is not... will check that.

that OLM is almost in range with scalance, that seems a little hefty considering you I can get almost 3 westermo modems for one OLM.
beats me why they choose their strategy that way...
still on beginning with other two options...

Is as you write the cable itself damaged ?
If that is the case, how does switching from copper to fiber help ?

Also, Cisco and Scalance are Ethernet products, not profibus.
The diagram you have posted does not make much sense if this is Profibus.
I sense a little confusion here.

edit: Also what kind of data transfer that is between the various partners affect what is possible and what is not.

edit: The use of profibus with exclusively S7-1200 PLCs that have native Profinet interfaces onboard also puzzles me.

JesperMP said:

Is as you write the cable itself damaged ?
If that is the case, how does switching from copper to fiber help ?

Click to expand...

the cable seemed not to be visually damaged, but it has seemed that characteristics were not the same after it was hooked with Caterpillar, and the communication was random and degrading...
however, optic was in plan anyway (and it should have been crossed in the construction but for some reason it did not).

as for advantages, optic does not have specific impedance, it is immune to EM influences, is galvanically isolated, it does not have predefined comm standard, and i think it is easier to fix (welding broken fiber would not influence the "resistance")

JesperMP said:

Also, Cisco and Scalance are Ethernet products, not profibus.
The diagram you have posted does not make much sense if this is Profibus.
I sense a little confusion here.

Click to expand...

Yes, quite right but let me clarify. it was profibus. now it's nothing. actually i can choose to stay on profibus or rewrite configuration and program and switch to profinet(ethernet). so what is in the picture is: 2 S7-1200 configured for profibus, optic cable between them and the question is:
stay on profibus or switch to profinet

and yes i know scalance is ethernet product. i thought it was in price range with cisco but obviously i was wrong.

JesperMP said:

edit: Also what kind of data transfer that is between the various partners affect what is possible and what is not.

Click to expand...

it is data transfer between 2 distributed plants (two wells) currently.

JesperMP said:

edit: The use of profibus with exclusively S7-1200 PLCs that have native Profinet interfaces onboard also puzzles me.

Click to expand...

currently those are 2 S7-1200 but there is project in progress where whole SCADA will be recreated and all the other water distribution sites and plants will be interconnected in ring.

but honestly, the profibus here was only because a project engineer designed it that way. i was also puzzled cause it should've been optic with profinet in the first place. but i got what i got and now i have to cope with that.

EDIT:
if anything else need to clarify feel free to ask. as i would consider suggestions.

balash said:

it is data transfer between to distributed plants (two wells) currently.

Click to expand...

What kind of data transfer ?
More specifically, Profibus DP master/slave, Profinet IO, or just plain polling and messaging ?

balash said:

[..] there is project in progress where whole SCADA will be recreated and all the other water distribution sites and plants will be interconnected in ring.

Click to expand...

That answers your question. Ethernet or Profinet in a ring.
If it must be Profinet IO then it must be all-Profinet devices with MRP support.
If not Profinet IO, any other solution that is based on ethernet ring with automatic recovery will be OK.

Forget Profibus over fiber OLMs. It is an expensive solution that is becoming less relevant with Profinet taking over more and more.

JesperMP said:

What kind of data transfer ?
More specifically, Profibus DP master/slave, Profinet IO, or just plain polling and messaging ?

Click to expand...

i thought you were meant that but didn't have my laptop here. now when i looked it, it is Profibus DP master-slave.
but in terms of control, these are two equal systems hierarchically.

JesperMP said:

That answers your question. Ethernet or Profinet in a ring.
If it must be Profinet IO then it must be all-Profinet devices with MRP support.
If not Profinet IO, any other solution that is based on ethernet ring with automatic recovery will be OK.

Click to expand...

yes, i am also more leaning to profinet currently, so i was wondering if the maybe profibus is better or will my office LAN influence the comm, but i can detach everything from it and leave only one connection point for SCADA...

JesperMP said:

Forget Profibus over fiber OLMs. It is an expensive solution that is becoming less relevant with Profinet taking over more and more.

Click to expand...

totally agree with that. :nodi:

The office LAN should not be part of the process LAN.
The simple end sensible solution, your SCADA PCs are connected to separate LANs for the process (the fiber ring) and the office via individial network cards.
edit: Another is to have a router between the two LANs. But I prefer the simpler solution. Easier to maintain without involving the IT department who may have incompatible ideas about how the two networks should be incorporated into each other.

JesperMP said:

The office LAN should not be part of the process LAN.
The simple end sensible solution, your SCADA PCs are connected to separate LANs for the process (the fiber ring) and the office via individial network cards.
edit: Another is to have a router between the two LANs. But I prefer the simpler solution. Easier to maintain without involving the IT department who may have incompatible ideas about how the two networks should be incorporated into each other.

Click to expand...

agree again, but for some specific reason at HQ site is missing some 20-40m of fiber cable to connect directly to SCADA. someone decided it is not necessary to go all the way through when we have LAN...
that will be corrected, i hope so, in planned reconstruction .