So, the official word from Digitrax support is that the UP5 will not forward command station traffic, nor will the UP90. It's confusing, as I opened roughly the same issue 2x, the first time they said it should work, and send back the unit. The second time, they were very clear, the DCS52 does not work with the UP5, and that the UP5 will only work with Throttles.
Investigating I think I can confirm most of what they said as I was able to verify the 52 and the 210 were exchanging messages (NET LED flickering on the 210), but I could not turn on power to the track. This roughly echo's what the service response said would happen. The two *could* talk, but because the 52 does not get a railsync response, it will not attempt to enable power to the track. You can plug the 52 into the second port on the back of the UP5 though, and that does work, because railsync isn't blocked between those two connections.
Overall, I'm sad, but I'll get over it. The 52 will make a great N scale controller for a my planned 4x6 layout in my office, and I got a new throttle for the Christmas train which they confirmed would work.
