E Drums and Keys at the same time

I want to be able to play and record my Yamaha electronic drum set and a  keyboard at the same time. The drum module has midi out and right and left out. I've been recording the drums using right and left and an armed midi track (muted) for some time now and it works great. I have a Tascam us1641 that has midi in and out. the key board also has midi in and out. I guess my question is what would I need to do as far as routing to have the drums (midi out) and keys going at the same time? I've never seen an interface with multiple midi inputs but surely this is not a strange thing i'm trying to do.

That makes sense. I might not have been clear... how would I physically plug two midi cables into my interface with only one midi in? would a midi to usb  cable / adapter solve this?

That's what I'm talking about. More of a physical splitter or merger in this case. Now I just have to figure out how to tell the daw to split these signals back where they belong. Of course I'll have to get a merger first! I'll probably be back, Thanks guys

Yes channels! I will try to config when I get the hardware
 

And I also was wondering about the keyboard and the Yamaha drums and which models they are as my Yamaha drums do use USB which you are correct have a different driver which has nothig to do with my ASIO drivers and happily co exsist. So that is a great idea given that is an option.  
If both instruments have USB then it's problem solved. 
If they are both midi only then it's back to the merge box. 
For me trying to use a thru port I always ended up with wierd things like missing notes as well as there can be added latency which is why I bought myself the merge box as well as a Roland A880 a long time back.
Of course the OP can always try that and it might work, but he did say the drums are midi out and not usb so let's see what they say.. 

If it its Midi only connectors you don't have to use a merge box as long as one of the devices has a Midi thru or a Midi output that can be switched to thru.

That was the whole purpose of Midi. just assign different send channels to the drums and keys. Drums are usually channel 10 anyway. Don't forget you can also record the audio as well as the midi by connecting the appropriate outputs from your drums and key to your audio device. It just gives you more options especially if you like the sound of your drums and or keyboard.

That's good to know Keni. I could go midi out of drum module..... into hardware synth midi in...... then midi out of hardware synth..... to midi in on interface ........and handle the rest with software

brundlefly
If either the keyboard or drum module has a THRU port (or THRU mode for the OUT port), you can "daisy-chain" them into one port without having to get a separate merger.
 
Also more recent keyboards usually have a USB MIDI port for which a driver will be loaded in Windows that presents the keyboard's MIDI ports to SONAR like any other MIDI interface so you don't have to use the MIDI DIN cable connections to your interface.

 
I have a similar daisy-chained setup with 2 midi keyboards. The one that connects to the PC does so via USB rather than a midi cable. Sonar "sees" them as one single device, but that's never an issue. You just need to set them to different midi channels.