Midi And Rs232; Remote Controlling The Adi-642 - RME Audio ADI-642 User Manual

11. MIDI and RS232

11.1 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-642 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-642, ADI-648 or a HDSP 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. Handling of the MIDI
input signal is completely
unaffected by the current
routing matrix setup, that is
the routing of the audio
channels.
To simplify the serial operation of multiple ADI-642s (see chapter 10.1/10.2), the MIDI sig-
nal coming in on the MADI port will be passed on from MADI to MADI when REMOTE is set
to MADI (see next page).
This removes the necessity for a MIDI cable connecting MIDI output and MIDI input of the ADI-
642, which would realize a direct pass-through of MIDI, from MADI input to MADI output, as
well.

11.2 Remote Controlling the ADI-642

The ADI-642 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-642 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 chapter 16.
The button REMOTE is used to select the source of the MIDI remote control commands, and
also the destination for the ADI-642'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-642 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.
User's Guide ADI-642 © RME
21