Thanks gswitz, not sure what that's about but probably nothing I'm interested in. I've asked Digitech to explain the MIDI drivers and why the RP255 shows up in Sonar's MIDI input and Output lists. Will let you know what they say.

It shows up in the midi ins and outs because there is apparently an editor program that can take control of it from a computer. It would work in one direction from computer to unit in terms of editor taking control the processor. The other direction from the processor to computer may only be for dumping programs and storing them etc. Not for sending the pedal movement though as a midi controller which is a bit of a shame and is probably not that hard to do.
 
I would investigate the editor though because they usually make very light work of editing the programs compared to adjusting all those parameters on the unit itself through menus and a very small display.
 
Here is the link to the edit software. It is called XEdit:
 
http://www.digitech.com/en-US/software
 
You can also stream audio between the unit and the computer. ie use it as an audio interface. Might be a good way to record through it ie plug guitar directly into it and stream its output digitally in stereo direct to your DAW I would say. It says it is 44.1Khz and can be set for either 16bit or 24bit. Nice! It also can stream the output from your DAW back to it and make the DAW available as analog signals on its main outs (and phones no doubt) Or stream the DAW out to it while your guitar is plugged in ie using your DAW as a backing track. I bet the total mixed signal (ie guitar and DAW) will either come out the main stereo outs or the headphiones. It should also be in the audio drivers as well as midi.
 
Otherwise you could just use it normally using the analog signals only. Digitech usually make great processors and I am sure it sounds pretty good.
 
But all this does not help your original request which was to control things in your DAW from a pedal which it cannot do. But my original suggestion would work connecting an expression  pedal to the unit I mentioned previously.
 
http://www.midisolutions.com/prodped.htm
 
This just allows you to connect a pedal into your midi data stream without investing in a keyboard controller which you may not want to do, understandably.

Thanks everyone! I was afraid of this. I already use XEdit which is pretty cool but was hoping for more. Oh well!
 
As for the Midisolutions solution, it's as expensive as the RP255 itself($120-$150). Probably cost >$25 to make. Hardly a reasonable option for me...

As for the Midisolutions solution, it's as expensive as the RP255 itself($120-$150). Probably cost >$25 to make.

It really is a great solution, but you'll also have to factor in the cost of an expression or volume pedal.  If you don't have one available, then you're up around the cost of a FCB-1010 (which is the only Behringer product that I've ever used extensively & recommended).
 
 
One more consideration for anyone thinking about this route:  The MIDI Solutions boxes derive their power from the MIDI In jack connection.  While that is a distinct advantage, you have to run the boxes inline within a MIDI stream.  Straight pedal-to-MIDI Out won't work without an auxiliary source of power. 

I bought an m audio oxygen 49 for 100 us last year on sale
it has 10 faders / 10 panning knobs / the play,rec,stop ,rr,ff buttons / punch buttons / loop buttons.
I hate m audio for there lazy driver updating skills but im using it on windows 8, that's about as fresh as windixie produce Ill
 
http://www.youtube.com/watch?v=wqB6QSrtx8U
 
this is how it set up with ACT I believe /this is the axion though, same set up, diff controller.
http://www.youtube.com/watch?v=gFaSICoEJ80

Awesome video, Charlie.
 
It's interesting that they didn't include a headphones jack. I suppose it is ONLY a midi controller. It doesn't have any internal synths so it cannot be played without a PC.
 
Interesting.