Digital Send and Return

In case someone needs to do this or something similar: 

• I just set up my TC Helicon VoiceWorks Plus as an outboard device with digital in/out.  In Sonar Preferences, I had to enable DIGITAL1 as an Input and Output device for the VS-700 interface.  I assume you have to do something similar for other interfaces.
• I connected coax digital in and out between the Voiceworks and the VS-700 interace.  (Coax cables look like RCA/phono cables but they are different, so keep your cables separated or marked.) 
• The VoiceWorks always has Digital OUT enabled but I had to go into the set-up menu and enable Digital IN.  At first it didn't work and I realized it was because I also needed to enable External Clock in the VoiceWorks set-up.  The back panel marked these as DI and DO instead of IN/OUT but that was somewhat obvious.
• I was going to use the VW as an effect on the lead vocal, so in the lead vocal track I added a Send to DIGITAL1.  (Your interface may call it something different—DIGITAL1 is the VS-700 name.)  Then I created a new audio track to receive the VW signal and set its INPUT to DIGITAL 1.
• After checking everything 20 times, I was seeing signal register on the VW, but nothing was coming back to Sonar.  I finally realized that I had stupidly left ECHO off on the track receving the signal.

Last note: In the VS-700 utility under Mic Pre, you can pick whether the digital connection is Coax or AES/EBU.  It defaulted to coax which is what I was using, so no problem there—just be aware that some interfaces may want you to make a choice to match your cable and port choices.