Okay thanks. Do I only use the red or the white one then? I can’t use both.

And can I use the ADAT I/O independently from the coaxial spdif also?

Regards

[ Edited after reading the response in #6: it turned out, that all questions were related to UCX II ]

Manual ch 21.3: you can use UCX II's digital I/O ports (AES, ADAT - switchable to optical SPDIF-, coax. SPDIF)
independent of each other.

Which means
- that all channels can carry a different audio signal and
- in terms of TM FX and routing: each digital output can have an individual submix like any other output.

SPDIF is a 2ch protocol, indeed you only need one SPDIF cable. So you have a 50 percent chance of getting it right first time.
If it doesn't work, well, then simply try the other plug of the breakout cable, it won't break anything.

According to another product's manual (HDSPe 9632) red is output, ch 6.1. I would assume that RME uses this schema for all products, should be documented in the UCX II manual, although it's effortless to find it out yourself.

Recommendation: you should read your manuals a little to learn about your device's capabilities. They are real gems. At least browse through the manuals, they are well-structured. Then you learn about the structure and what information you can expect from it.

Independently means independently. It wouldn't be that if all three outputs had the same signal.

Thank you. The manual actually doesn’t say independently, it says simultaneously.

From the manual:
“21.3 SPDIF (Coaxial, Optical)
The Fireface UCX Il has up to three SPDIF inputs and outputs: coaxial, optical and AES can be used simultaneously, with different audio signals. Note that the sources have to be synchronous, as the unit does not have a dedicated sample rate converter.”

It says simultaneously with different audio signals. But what does synchronous mean?

Thank you
Regard
Bjørn