[BRLTTY] Error "Can't determine tty number"

[a c]

Hi,

I'm writing some C++ code on ubuntu, trying to connect to a Papenmeier Braillex EL 40s and just write some characters on it, for a start. However, when taking control of the tty using the default tty number (brlapi_enterTtyMode(BRLAPI_TTY_DEFAULT, NULL)), I get an error: "Can't determine tty number". I tried to figure out what this number should be, but didn't manage; and also tried some more or less random numbers, and when I do this, it says "brlapi_enterTtyMode: Ok", but then does not write anything on the Braille Display, nor does it recognize any user input.
Could someone please help me out? I would very much appreciate it. Please note that I'm a novice in everything (linux, C++, Braille api's), so please take that into account when answering.

Thank you very much!

Best,
TW
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