Thank you for the clarification, @Martin-Kudláček .

So, I can't use a DE-9 to Rj-11? Is the USB-A on the HMI a RS-485? Is there some guide for this?

Hello,

I'm not very knowledgeable about communication, so a lot of detail would be much appreciated.

I want to connect my WeIntek MT8071iP to by UniPi 1.1 without needing a network connection. Is this possible? What are the required cables?