Communication between Beckhoff I/O cards and S7 cpu

Greetings all.

Kinda new to the forums and to the automation world as well, so bare with me if possible :)
My issue at hand is this: 

At the moment we have some cooling stations controlled by 4 industrial pc (one for each unit) with a series of Beckhoff I/O cards. Due to some issues we had with the PCs, we decided to make a change to 4 s7-300 cpu (I am thinking a version of 315 but this is another issue for another place). I am trying to determine if it would be best to keep the I/O cards instead of installing a new remote I/O.

In this case, I have found out that what I will need is a Beckhoff EK3100 bus coupler which would be responsible for taking the signals from the cards to my new cpu via profibus. I asked a local Beckhoff retailer about it and they suggested this, or a EK9300, because, as they said, EK3100 does not support gateway terminals.And this is where I lost them :)

Has anyone seen something like this? Is it working as intended? Either with profibus from the cards to the cpu and from there to the profibus network, or with profinet from the cards to the cpu and with profibus to the network.

I have found the GSD files but I wanted to know beforehand as I have access to few s7 cpus and some spare I/O cards though in order to try it I will have to get one of the bus couplers.

Thank you in advance for any ideas you might have

Hello jbeta;

We have worked with Beckhoff Profibus couplers in some projects, mainsly with this one:

https://www.beckhoff.com/english.asp?bus_terminal/bk3110.htm

The coupler allows the Beckhoff I/O modules to act as a remote I/O slave for the Profibus master, and since the S7-300 CPUs mostly come with an integrated Profibus master interface it becomes very easy to bring them into the hardware configuration and the program of the PLC.

In the same page you will find links to other models of Profibus couplers from Beckhoff, if you want to see other selections.

If your PLC has an extension -2PN/DP in its descriptor, then you can also decide to use Profinet, with the Beckhoff I/O as part of a Profinet I/O station. Here is a product descrition page for a Beckhoff  Profinet coupler module, with other similar product links at the bottom of the page.

Hope this helps,

Daniel Chartier

Thank you very much for your quick answer. It is much appreciated!

Now I started thinking what is the difference about the two EK3100 and BK3110 but this is the wrong forum for that :)
Your experience with this though has assured me.

Thanks again

Hello

The EK3100 is a Beckhoff PLC with Profibus interface; in this case it would be equivalent to a CPU 315-2DP.

https://infosys.beckhoff.com/content/1033/ek3100/3974742923.html

The BK3100 is a Profibus head module for a remote I/O station; it would be similar to a Siemens IM 153-2. That is why it would be esier tœ use a BK3100 to connect Beckhoff I/O modules to  Siemens CPU over Profibus.

Hope this helps, 

Daniel Chartier 

Ah I see now. Your help has been invaluable. 

Thanks again!

Hello jbeta;

I have been told by a collegue who works with Beckhoff systems that I have given unreliable information to you on the EK3100.

It is not a CPU module for Beckhoff systems with Profibus interface; it does not accept TwinCat programming.. It is a Profibus coupler, as the BK3100. However there is one major difference: the BK3100 connects Beckhioff I/O to the Profibus master the coupler is attached to, while the EK3100 connects a Profibus master to an Ethercat extension. The EK3100 translates all the Profibus requests to Ethercat exchanges, an can then be connected to Ethercat coupler modules further down the network.

It is a subtle difference, but we both agreed that in your case the BK3100 would be the way tosetup your Profibus node.

Hope this does not confuse you,

Daniel Chartier.

Hello again.

If I understand this and what the coupler's page is saying correctly,

EK 3100 is used to connect the attached, via profibus cable, master directly in order to communicate with the I/O cards,  ("The EK3100 Bus Coupler connects PROFIBUS networks to the EtherCAT Terminals ... One station consists of an EK3100 and any number of EtherCAT Terminals. The coupler is connected to PROFIBUS via a 9-pin D-sub plug")

while BK3100 is used for the same thing plus it has the ability to connect more I/O blocks after the one it is attached to ("...connect the PROFIBUS system to the electronic terminal blocks, which can be extended ... One unit consists of the Bus Coupler, any number of up to 64 terminals and one end terminal..." with the end terminal providing the connection to the other blocks via its RJ45 port).

But if that is so, and correct me if I am wrong, wouldn't EK3100 suit me beter, since I only need for the single block of I/O to communicate with one CPU (or 4 blocks in my case communicating with 4 CPUs). 

Thanks again for your quick answers and for sticking with me. Your help is much appreciated!

Edit: In hardware configuration, while EK3100 gives me a list that contains the exact modules that we already have like EL1008 digital and EL3024 analog inputs and EL2008 outputs,

BK3100 gives a KL list of terminals plus a generic one like 8bit digital input and there is no show of the analog ones that we use... Not sure if it counts for something..