Hey Fellow Music Junkies,
 
     "How do I connect my Roland TD12 Electric kit to my Roland Octa-Capture Audio Interface to my computer?"  I would like to be able to control each midi hit/trigger in Addictive Drums 2.  I specifically was thinking of using a MIDI to MIDI cable.  Thus MIDI Out from the TD12 to the MIDI In on the Octa-Capture and than the Oct-Capture connects to the PC with a USB 2.0 on Sonar Cakewalk Platinum.  Will this work?  Any advice is welcome, I have tried watching many videos and they all recommend going from MIDI to USB directly, which I don't want to do, because I want it to go through my Octa-Capture.  Lastly, is there anything I should be aware that might damage my systems while working with MIDI. Thanks a million as my studio will be complete once this is figured.  I can't wait, cheers!
 
MIDI TO MIDI CABLE PIC:
http://www.mogamicable.com/category/bulk/dig_interface/midi/
 
ROLAND TD12 I/O PIC:
http://en.audiofanzine.com/electronic-drum-module/roland/td-12-module/medias/pictures/a.play,m.606989.html
 
ROLAND OCTA CAPTURE:
https://www.roland.com/us/products/octa-capture/
 
Best Regards,
      Cameron Graham

Yes that will work fine, not sure why you want it to go through the octacapture?  I would try both
ways , there should be not difference in midi timing but it would be good to test both ways out.
   but the answer to your question is yes it will work :)

I use the TD-12 with AD2 all the time. First off, I would suggest not using any audio from the TD-12. Just use MIDI out from the TD-12 into whatever your MIDI input device is. Then use AD2 and have the MIDI input signal on the AD2 track coming in from your MIDi interface.

Listen to / record your drum performance through your audio interface using the AD2 sounds.

Thanks for the advice on this and yea I will definitely use AD2 with it via MIDI.  I really appreciate it and I will be testing it today. I will confirm afterwards that I got it working, or if I have any issues. I can't wait to get it setup. 

Listen to / record your drum performance through your audio interface using the AD2 sounds.
 
This depends on how much system latency you have. For me I monitor both VST and Drum set  with a blending and put the drum set output louder. Otherwise there is a touch of delay which throws my timing off. 
Make sure you bypass all effects that might add latency. 
And for me I found the USB midi connection had less issues as I think it takes one device out of the pathway. 
Make sure to update your Roland drivers for the drums midi usb. 

As long as the audio interface is fast enough there's no need to listen to the audio output of the TD-12 brain. 
 
There are plenty of tips to reduce latency in the Sonar section of the forum.  A few highlights being 1) to ensure you do not have any network adapter active (or wireless adapter) while recording/tracking and 2) to not have effects active on any tracks while recording.
 
However, that said, if the audio interface is not that snappy, then the converse strategy is to listen only to the TD-12 audio output (for the drums mixed in with the other playback tracks of the song), and not listen at all to AD2.  That also is a reliable strategy.  Then after recording the drums, you go back and listen to what you performed through AD2, and have the TD-12 output complete off.  The disadvantage of that is you can't take advantage of what you might have set up in AD2 to hear while playing/performing the drums.  The advantage is that you can be spot on with timing.
 
But, if you have next to no latency, as outlined at the start, it's better to only monitor through AD2 and have the TD-12 audio output completely silent while tracking/recording.

Yes absolutely system dependent. He has a Roland interface which I do believe are not great performers. 
The delay I get is probably the reported output latency of 5.5 ms. But somehow it seemed worse with the drums, more like I'm getting 12+ ms of delay.
It's possibly that my Yamaha DX 450 drums have midi output latency.  I don't have this problem playing on my Keyboard controller. 
Anyway's it's simple to test,
Just rig it up so you can hear both at the same time, you'll immediately hear a digital delay. 

Cactus Music
Yes absolutely system dependent. He has a Roland interface which I do believe are not great performers. 

Very true. I could never play AD2 or Kontakt drums via my TD20 when still using Roland interfaces. The lowest buffer setting would still yield a minor latency that felt odd and unnatural.

You need a top notch RME or MOTU interface plus a strong DAW where you can run latency as low as 2 ms to make for natural playing ... mind you then your MIDI latency is probably bigger than your audio latency so it'll be worthwhile to measure that (although here Roland often outperforms MOTU and alike)

Great news, the Td12 connected via midi to midi cable to the Octa Capture to the PC worked flawlessly once it was setup. :) I used ADD2 for the VST drum sounds. We started recording already and even had a live jam with only VST's running through the PA on all our instruments. So much fun! Thanks a million for all the advice on the subject everyone. Anyone in the future let me know if you similar questions on the subject. Cheers!

Rob, what Roland interface was it that you were using? Live jamming through the PA was no issue for my drummer with a full band also being ran through 64 bit VST's, but he did complain about playing to the metronome specifically when recording with drums. I figured it was metronome timing denial on his part, lol. I was able to hold a beat to it when I tried it. How do I check to see the latency of it to get it under 2ms? I just want make sure I'm not terrorizing my drummer ears with unconfirmed latency, lol.