1. Digital Sample / Word Clock (WC) Sync
Getting the right digital sample / word clock combination is a matter of trial and error. I have found that generally the 112d (or other MOTU device connected to the DM via a converter) is best as the master clock source, the Dm is set to external clock source Word (BNC from 112d WC Out to DM WC in), and the converter either is clocked to the interface or the board, either via Word Sync BNC cable in between the two, or some form of internal sync (AES 1-2, TDIF, etc.). Sometimes u can chain the sync cables using the THRU or OUT BNC jacks, sometimes u need a T adapter, other times u need a dedicated clock or clock distributor. Experimenting diligently will help u find the right solution for u.
Note you will sometimes have to power cycle the board, interface and any converters as you experiment w configurations, but once u find one that works u should be golden.
Last two must-do points: do NOT loop BNC connections between first and last devices (clock is one-way, but can be split) and ALWAYS make sure all devices are set to the same exact rate (44.1, 48, 96 etc)