MKR 485 shield DC isolation at max (Arduino talking with a Grundfos pump)

Official Hardware MKR Family MKR Shields
21

Here follows the screenshot where it says it is GENIBUS over RS485. Same Spanish document, sorry.

Screenshot_20230827_234817_OneDrive
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Oh you mean the control unit could be the one providing the GENIbus over RS485 to a third party device, while using something propiatory from the controller to the pump, right?

Is there a reason why RS485 is incompatible with the power wires? If it was, why does this arduino shield provide 50VDC isolation?

23

Have you researched "data over power wires" to see what is involved?

24

If you have a CIU then see section "4.3.1 Connection of power supply and GENIbus" in the CIU Installation and operating instructions

image

It sounds like a CIM module is inside the CIU and does the communication with the pump. The documentation is lacking basic information such as a block diagram showing how thing are connected together.

Effectively the order appears to be:
Pump -> CIM & CIU -> RS485 -> Arduino

25

It's not designed to work over power wires. If you want to put 2 very different electrical signals on the same wires then you have to design circuitry to do it. RS485 was designed to work over wires not shared with anything else.

I think @mikb55 has answered your question.

26

Thanks a lot. I missed that genibus pin connection and missunderstood the whole thing.

600€ plus would solve the issues and let the RS485 signal work without worrying about any DC voltage.

But it is too expensive. Not worth it for now. I will just irrigate regardless of the pump and pray it doesn't have any issues.

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