if you are able to manage the protocol of EXTIO pseudo serial, it is possible to use this serial.
EXTIO pseudo serial (a 3V TTL serial) accept only dispositive CAT commands, not being able to send answers.
To be clear: if you send FA; you do not have answer.
On EXTIO pseudo serial DUO send, many times per minute, a computed FFT and a report on the set of DUO,
so we can use EXTIO for sending CAT commands, and reading from EXTIO the result using the protocol described in ELAD document.
This has been done in BlueDUO (EXTIO linked by Bluetooth serial) and in EladRemote (through network and DUO ART).
Arduino seems to not have enough memory to manage the full status of DUO (but I'll investigate this subject), and, worst,
Arduino do not have a native USB HOST interface (to read MIDI), so I prefer not to use Arduino as first approach (maybe in future, who knows ;-) ?
For Raspberry (my preferred starting device) we can test the serial first interface, but we have to twiddle this serial with the bluetooth one,
because only one of the two is an "hw serial", the other is a "sw" one, painfully slower. And, int their infinite wisdom, rpi developer have given precedence to bt serial.
But, at the end, a simple 5Euro (or less) USB serial adapter can be used to connect EXTIO if someone is interested.
From the point of view of the speed remember that CAT and EXTIO can run up to 115.200 kbps, so there is not difference betweern the two technologies.
Giovanni - HB9EIK