RME ADI-648 [18/32] Midi transmission

User's Guide ADI-648 © RME

10. MIDI

10.1 MIDI Transmission

MADI allows for a transmission of 64 audio channels over long distances with a single line –

perfect. But what about MIDI? Be it remote control commands or sequencer data, in practice

only a single MADI line will not suffice. Therefore the ADI-648 also has a MIDI I/O port. The

data at the MIDI input are being included into the MADI signal invisibly, and can be collected at

the MIDI output of another ADI-648, or a Hammerfall DSP MADI, at the other end of the MADI

line.

Technically every single MADI channel includes several additional bits, containing various in-

formation (Channel Status). RME use the usually unused User Bit of channel 56 (channel 28 in

96k Frame mode), to transmit MIDI data invisibly within MADI, ensuring full compatibility.

The block diagram shows

the basic MIDI operation.

The MIDI input signal is

added to the MADI output

signal. The MIDI data found

in the MADI input signal will

be available at the MIDI

output. This functionality, a

bi-directional MIDI/MADI

converter, is always avail-

able, and not affected by

the REMOTE key.

The MIDI input signal will never be transferred directly from MADI to MADI, no matter how the

matrix router is set up. A MIDI cable connecting MIDI output and MIDI input of the ADI-648, will

realize a direct pass-through of MIDI, from MADI input to MADI output.

10.2 Remote Controlling the ADI-648

The ADI-648 can be completely remote controlled via MIDI. The CPU shown above reacts on

specific commands. Furthermore, upon request the CPU will report the complete device status.

This includes all controls and LEDs on the front plate. Each ADI-648 can be programmed with

its own ID, providing a separated remote control of multiple devices via a single MIDI channel. A

description of the MIDI implementation is found in section 15.

The key REMOTE is used to select the source of the MIDI commands, and also the destination

for the ADI-648's request replies. A push on REMOTE toggles between MIDI port, MADI port

and Off. The latter is a safety function to prevent any setup-change by any MIDI signal. In the

picture above, the MIDI commands reach the CPU via the MIDI input, and the CPU's feedback

on commands is only available at the MIDI output.

To remote control an ADI-648 from a Hammerfall DSP via MADI, REMOTE has to be set to

MADI. As can be seen in the block diagram on the next page, this setup provides a complete

data path for MIDI in both directions.