The MIDI interfaces that worked under Apple MIDI Manager, or with older software like Finale 2.0, always had a limit of 16 channels per serial port; because the MIDI data format was carried directly over the serial ports.
The older interfaces don't have their own CPUs and MIDI merge chips, so they all worked that way, even if there are 2 MIDI-INs and 2 MIDI-OUTs. The Opcode MIDI Translator Pro was one of the most common ones like that.
To connect more than 16 channels to a serial port, the interface needs to contain hardware that interprets and routes MIDI messages, and it needs to have a driver for OMS or FreeMIDI. The extra layer of data conversion also adds latency.
I can't find the Pocket Express manual, but its archived marketing page at motu.com promotes "fully independent, paired outputs", which sounds a lot like a 1:1 association of MIDI port to serial port. The interface isn't completely "dumb", though, because it has LTC to MTC and MTC to LTC timecode processing. There may be requirements for which port (A/B) receives timecode.
Translating all 32 channels to parallel could require more processing power, so it's possible that this unit contains the same or similar components to the MTP AV.
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Topic: MIDI Interfaces connecting via Serial (without audio i/o) (Read 278442 times)
