How do I connect the modx? Using 5-pin midi cable directly to the sound card simply?

That would work.
Set the MODX to slave to MIDI clock... make sure you are sending it (MIDI Clock) from your DAW (Logic)

Press the Quarter Note icon on the top line of the MODX screen to see Tempo Settings
Set MIDI SYNC = MIDI

In Logic make sure you are sending MIDI clock to the Saffire’s MIDI ports.

The MODX’s tempo driven items will reference the clock coming from Logic. This includes the Arpeggiator, the tempo driven effects, the tempo driven LFO, the Motion Sequences...
Hint: It is still your responsibility to trigger the Arpeggiator in time.
Use “Auto Sync Quantize” to help your start and control timing.

Great! Thanks Bad Mister! There are some things I don't know how to do: How do I set the modx as a Logic clock slave? On the other hand, I can't find the "Auto Sync Quantize" function, where is it?
Which direction does the midi, midi in in modx and midi out in Saffire, or vice versa?
Sorry for my great ignorance. Thank you!

No problem.

How do I set the modx as a Logic clock slave?

Press the Quarter Note icon on the top line of the MODX screen to see “Tempo Settings”
Set MIDI SYNC = MIDI
That’s all you need to do on the MODX side of things. You will need to consult the manuals for Logic and the Safire. You want to make sure that Logic is sending MIDI Clock to the Safire.

On the other hand, I can't find the "Auto Sync Quantize" function, where is it?

When working with Arpeggiators on the MODX, this parameter will allow you control the Arpeggio. When you set this to a musical note value (for example, 480 clocks or a quarter note), you can hit the controlling/triggering note for the Arpeggiator within that much of the downbeat. The Arp will start exactly on the downbeat. It gives you a bit of timing correction on your initial note-on events.

There are 8 Arpeggiators in the MODX. They can be used in numerous ways to enhance your music. With each Part you can assign an Arpeggiator. On each the Part’s “Arpeggio” screens you will find “Sync Quantize” — that is what this parameter is for.
From the HOME screen
Touch Part 1 in the screen
A pop-in menu appears, tap “Edit”
Touch “Arpeggio” > there are three different screens to set the Arpeggiators. “Common”, “Individual”, “Advanced”.
At the top of each of these screen you'll find “Sync Quantize”

Which direction does the midi, midi in in modx and midi out in Saffire, or vice versa?

Always think “Signal Flow”. If Logic is going to be the master clock, and the MODX is going to be clock slave, logically speaking (no pun intended), then MIDI clock travels Out from Logic to your interface, and the interface sends it Out to the MODX. You need to connect the MIDI OUT of the Safire to the MIDI IN of the MODX. Make sense?

Fantastic Bad Mister, everything was clear! Midi out saffire midi in modx!

Thank you!

There is something that I have not commented that I fear is important in this whole story. The distance between the modx and the saffire will be great because the sound card is not controlled by me but by the drummer. I need a midi cable of at least 10 meters. In addition, thanks to the update to 2.0 for modx I can connect the wireless alesis controller to the modx usb. Can I simultaneously use both ports, usb for alesis and midi din to receive logic?

Thank you!!!

MIDI spec maximum distance is 15 meters (50 feet) so your MIDI cable of 10 meters should be fine if both devices adhere to MIDI compatibility.

From what I understand of the new feature - it works regardless of the MIDI setting (MIDI set to USB mode or MIDI DIN mode). So I would think MIDI inputs from both the MIDI DIN port and USB TO DEVICE port should be supported. I haven't tested this - so someone else can provide a more definitive answer.

Okay Jason!

I think everything will be great. Now we need to know how to configure the modx so that everything runs smoothly with the double midi path.

Thanks for your help Jason!

Can anyone confirm the compatibility of both midi ports? midi din and midi usb?
If this is how it seems ... do you have to do something special in the configuration of modx, or is everything going well by default?
Thank you!!!