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Adding 3rd party ethernet devices to the BlueROV2

Hi There,
I want to use the BlueROV2 as the chassis to carry a robotic payload. Before I buy, I need to be convinced without a shadow of doubt, that I can actually talk to my equipment on board, via the BlueROV2’s tether, and without disrupting the BlueROV’s normal functioning. I can do everything I need to do over a generic ethernet connection.

My question is simply: Does the tether provide a normal ethernet connection?

For example, what a “normal” ethernet connection means to me: I could add small ethernet switches on both ends of the tether. On the surface, plug your controller into the switch. And in the sub, plug the raspberry pi into the switch. Then, I could add my own gear on both ends. Would the BlueROV2 work normally in this scenario? And can I run my own network code in parallel, sharing the tether with the BlueROV2? (I don’t have a ton of data, so assume the contribution to network traffic would be low compared with the BlueROV’s video feed)

Finally, a “normal” ethernet cable would have unused wires. I saw images of the tether’s wires, and they look very much like normal ethernet to me. But can you confirm that? Which wires of the tether are actually used? Is there any reason I couldn’t do whatever I want with any unused wires? (In addition to the switching question above)

cheers,

  • Zauberkugel

Hi @Zauberkugel ,

The tether carries 4 pairs of wires, just like a normal ethernet cable, but for regular operations only one pair is really used, as the Fathom-X Interface Board provides long distance Ethernet connection over two wires. You could use another set of board to have a completely independent network.

Take a look at https://bluerobotics.com/store/comm-control-power/tether-interface/fathom-x-r1/

— VMartini

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That looks useful, thank you! It looks like I can work with that module, as one option.

However, just to have a different option – how about the first part of my question: What if I want to use the same wires as the ROV for some reason (for example, with the slim tether that has only 2 wires, or because I’d just rather have everything on the same network, rather than on separate networks). Would there be a way to use ethernet switches to add devices to the BlueROV2’s own network? Does my concept of the BlueROV2’s “own network” even make sense, or does it use some non-standard protocol?

John - Below is a thread that discusses the BlueLink DEPS MUX that replaces the Fathom X board and allows for 2x Ethernet up a single twisted pair plus 12/24VDC power.

The route of using a board level switch can also be implemented. Aliexpress.com offers a few options for 3-6 port OEM ethernet switches.

We have used regular network switches before on Ethernet payloads, they work fine: Sonar connection via the RPi ethernet?

It is the standard Ethernet protocol, nothing special.

Very cool, thanks everyone for their input. @bluerobotics, that was my order that just came in :slight_smile:

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