Finally got access to an E2 to test. So indeed Daniel is correct. YOU HAVE TO HAVE AN ARGUMENT after the ATRN command line. If you leave it blank it doesnt work. We ended up with a TCPSend(1,"ATRN 60[cr]") This seemed to be a good start point for dissolves.
Also, while we were testing this, we found a problem with using WD and even Barco's preset manager while the Event master console was plugged in at the same time. With the Event Master console plugged in, we could recall presets with the Widget App, but it would not fire any transitions. When you unplug the console, Both widget and preset manager would work fine. Barco is aware of this issue, and has it in for its next release. Here is the email from Barco:
Problem in version 4.1.1235 is that the ATRN command when used without a frame count behind it would not work so ATRN or ATRN 0 did not fire the transition. Workaround was to supply ATRN 1 or higher to fire the transition.
The fix is in the patch 4.1.1279 version and will be in the official release of 4.2 due out July 7th.
After this Update the command TCPSend(1,"ATRN [cr]") should use the current dissolve rate that is being used by the console.
Here is a photo of finished project On an Event Master Console. This is triggering 3 pairs of E2 Frames. 6 in total. This can recall and save presets across all the frames, as well as trigger the trans / cut command.