> ... one instrument is on Midi channel 16 and the other is on midi
> channel 1.

The MIDI channel assignments are not fixed - they are settable by the
user.

The user choses a 'base' channel, and then additionally can specify how
many MIDI channels to use.

By default the Polaris will use 3 MIDI channels:

base = main instrument
base + 1 = link instrument
base + 2 = sequencer

The base channel is set with buttons 1-6 after selecting "LF + MIDI
Channel".

The base channel is the sum of the numbers you choose - so if you select
(for instance) just button 1 - then that's a base MIDI channel of "1".
If you select button 1 and 3, then that represents 1+3 = a MIDI base
channel of 4. If you select 1+4+5+6, then that's a base channel of 16.

If the base is 16, then base + 1 will wrap around to "1".

> I can control the polaris on midi Channel 16 or Channel 1 and the
> individual sounds from the linked patch.

This is how the Polaris normally works. Specifically - from MIDI, each
MIDI channel is connected to an 'instrument' - not a 'patch.'

So - for instance - let's assume that the patch which is desired is K-3,
and let's also assume that that is a 'link Unison' with J-6. (and let's
assume the 'base' channel is set to '1')

From the Polaris' panel, when you press "K-3", there will actually be
two different program change messages appear on MIDI:

Channel1 (main instrument): Program Change for Prog 123 (K-3)
Channel2 (link instrument): Program Change for Prog 114 (J-6)

Now, forgetting about the keyboard on the Polaris - consider it only as
6-possible 'instruments'. If from MIDI you send a program change "123"
on channel 1 - and then send data on channel 1 - then ONLY the base
program (K-3) will play on the Polaris. You will not hear the 'link'
program.

If you want to hear the 'link' program, then you would send to the link
instrument (e.g. base MIDI channel + 1).

> > The issue is the Polaris will not play both the main and linked
> > sound if I tell it to play
> on all channels, only one "instrument" plays from the Polaris.

You want/need to ensure that the Polaris is not configured for 'Omni'
mode (where it listens to all channels, and will direct all that data to
a single instrument internally).

E.g, Lower Function + Cassette, 9 (MIDI Omni Mode) should be off.

You generally do want MIDI Panel Switch enabled (e.g., Lower Function +
Cassette, 8 = on).

> Subsequently if I create two "instruments" inside logic and tell the
> Polaris to play
> from midi Channel 16 on one and Channel 1 on the other. The Polaris
> defaults to one of the
> instruments only and does not play two instruments at once.

As long as Omni mode is not on, and the Polaris can receive program
changes, then this should work fine.

In the example above, that means:

On MIDI Channel 1, send a program change message for program 123
On MIDI Channel 2, send a program change message for program 114

Now, if you send MIDI nodes on Channel 1 - program 123 will play on the
Polaris. If you send MIDI notes on Channel 2 - program 114 will play on
the Polaris. If you send notes on both Channel 1 and 2 at the same
time - then both progroms 123 and 114 will play at the same time.

Note - from MIDI, the Polaris is not limited to just a 'main' and 'link'
program. You can actually play up to 6 different patches at the same
time over MIDI (each 'instrument' will get its own MIDI channel.
Logically, the Polaris will look like 6 different synths, all reachable
on their own MIDI channel).