Which standard use for custom communication DC
You should consider Fast Ethernet (100Base-Tx) with power over Ethernet (PoE). You can use a 4 wire UTP for that without the possibility to damage a computer at the other side, but you have to be careful with your current of 1 A. When using PoE, the current flows through the coupling transformers windings and 1 A will probably be to much.

If you are looking for a simpler solution you should have a look at the AS interface (ASI bus).

Or build a custom solution which is a little fiddly and could involve capacitive coupling like shown below (DC free channel coding required).







simulate this circuit &ndash; Schematic created using CircuitLab

Answer to your updated question:

UTP is just a standard for wires and does not describe the kind of connector that is attached to it (western RJ45 for Ethernet connections to computers). Therefore you can use UTP without doubts. Aggreed?