manual/include/working-with-extenders.html

<p>
  There are currently 5 devices pre-configured to work with extenders.
  Two of them are for one master and one extender with the master on the
  right side or master on the left side. There are three presets for a
  master and two extenders with the master on the left, in the center
  and on the right. While these files will work for many uses there may
  be cases where a custom device profile makes more sense.
  The best way is to start with the *.device file in the <a
  href="https://github.com/Ardour/ardour/tree/master/mcp">
  Source Tree</a> that matches your
  master device and copy it to a new name such as xt+mc.device in the
  <a href="@@files-and-directories-ardour-knows-about">
  user config</a> sub directory <code>mcp</code> and then edit that file. It is best to
  name the file with the order the devices are expected to be used in as
  the position of the master device is specified in this file.
</p>
<p>
  The three lines of interest are:
<p>
<pre>
 &lt;Name value="Device name"/&gt;
 &lt;Extenders value="0"/&gt;
 &lt;MasterPosition value="0"/&gt;
</pre>
<p>
  Add any lines that are not present.
</p>
<p>
  The <code>Name</code> value should be a unique name so it is obvious
  in the list of devices (so change it).
</p>
<p>
  The <code>Extenders</code>
  value is the number of extenders used and should not include the master in
  that number.
</p>
<p>
  When an <code>Extenders</code> value of greater than 0 is used, extra midi
  ports will appear for the extenders to be connected to. The MIDI ports
  for the controllers will be named <code>mackie control in/out</code> for
  the master, <code>mackie control in/out ext #*</code> where * is the
  position of the extender from left to right. So for a master in the middle
  with an extender on either side, the ports from left to right will be
  mackie control in/out ext #1, mackie control in/out and mackie control in/out ext #3.
</p>
<p>
  If using the MCP GUI to connect surfaces the top surface is the leftmost
  and the bottom is the rightmost. The GUI shows explicitly the position
  of the main or master surface within the group of surfaces.
</p>

<figure>
  <img src="/images/mcp-extender-position.png" alt="The Mackie Control Device Dialog">
  <figcaption>
    The Mackie Control Device Dialog
  </figcaption>
</figure>

<p>
  The <code>MasterPosition</code> value is the position the master unit
  (with the master fader) is located at within the group of surfaces.
  The surfaces are numbered from 1 at the left side and up. So if there
  are three surfaces, <code>&lt;MasterPosition value="1"/&gt;</code> will
  expect the master on the left, <code>&lt;MasterPosition value="2"/&gt;</code>
  would be master in the middle and <code>&lt;MasterPosition value="3"/&gt;</code>
  would be master on the right.
</p>
<p class="note">
  The default value of <code>&lt;MasterPosition value="0"/&gt;</code> has
  the same effect as <code>&lt;MasterPosition value="1"/&gt;</code>.
</p>
<p>
  If the <code>MasterPosition</code> value does not properly match the
  physical position and MIDI port, the master fader and global controls will
  not work. The master unit will act like an extender.
</p>