Bus couplers and RMP

Hello team,

I’m trying to learn more about how IO bus couplers work on the EtherCAT network. Right now, I have a limited understanding of how things work. I have collected some of my thoughts and questions below.

Generally, how can I expect a bus coupler to present itself and its attached IO cards in RapidSetup? Should I see the bus coupler as a single network node that has all of its attached IO cards added together and presented on the single bus couplers network node (example: 128 digital inputs, 64 digital outputs, 32 analog inputs and 16 analog outputs all on the first and only node).

Or all IO cards will be listed separately despite them not actually being EtherCAT.

Or maybe I will not see any of the IO cards as IO points, instead I should use SDO reads to read their digital input statuses.

Where does the magic happen that exposes whatever IO is mounted after the bus coupler onto the EtherCAT network. Is it the ESI file or through the bus couplers firmware?

Maybe bus couplers need a separate commissioning tool/software for setup to specify which IO slots will follow.

To be more specific, I’m trying to implement an IO EtherCAT bus coupler into RMP. It is called OPRIOBCM02 by ISAC: https://isacsrl.eu/en/tipologie/i-o-distribuiti/# Right now I only see the bus coupler and none of its attached IO listed in RapidSetup.

Any pointers to help me get a better understanding is appreciated, thank you in advance.

Hi Jesper,

There are different strategies which are used by Nodes. Beckhoff’s E-Bus, for example, keep each module as its own EtherCAT Node. K-Bus, IOLink, MDP, and many gateways require a fair bit more configuration to get working. They will appear on the network as a single node with all the associated IO. However, they normally subdivide their descriptions as modules. You would see something like…

Node X.Module Y .io A
Node X.Module Y+1 .io A

K-Bus is older technology which is handled automatically by our software so shouldn’t require anything on your part. The magic happens at discovery and ENI generation under the hood.

MDP and IO-Link both involve you making edits to a MDP.xml file. Support was recently (10.4.0) added for these two options. If you want to use either of these options, I can get you the procedure required.

Gateways tend to follow one of two strategies. Either they include details of their max capacity which is wasteful as it is largely unused in most applications -or- they provide an empty description file. They often have utilities which generate new ESI files after you’ve hooked up hardware to them.

The first thing I would do is look at the manual and ESI file to see if I could determine which type of strategy it was using. You can also use SDO Read of 0x1000 Sub 0 to get Device Type. That can help me identify what you are using.

Thanks Jacob. For future readers the documentation now includes a great article desbricing MDP. It can be found here: MDP - Docs