Here's one our Tech Support department sees very frequently:

"I am controlling my MDM (Modular Digital Multitrack) from my computer software via MMC (MIDI Machine Control) but they do not stay in sync. I have the connected the MIDI out of the computer to the MIDI in on my MDM and I am sending MMC from the computer. Why do they not sync up?"

With your current setup, you are not actually synching the MDM and the computer. MMC commands do not contain time code sync information. You need to have your MDM output MIDI Time Code and have your sequencer set to slave to MTC. You will also need both MIDI in and out connected between the computer and the MDM.

Here is the general chain of events:

1. You press play on your sequencer and it sends a MMC command to the MDM, telling it to start playing. Since the computer is set up to slave to incoming MTC, the computer is still not playing as it is awaiting time code to drive its clock.

2. The MDM starts playing as soon as it gets the MMC start command and when it starts playing it outputs MTC.

3. The MTC from the MDM is received by the computer and the computer starts playing its sequence in sync with the MDM.