I bought one at York last month just for track power, it’s all hooked up and works fine EXCEPT, while running trains for any length of time, the handheld unit times out which of course then does not allow the “Emergency Stop” button to function.
Is there any setting I need to change so this will work when I need it?
David,
That is a newer model of the TE and I don’t think there is a fix. You might just have to learn to hit the on/off before the emergency stop. However, then I guess you might turn it off if it is already on. 
Maybe you better ask this on the Aristo Forum. 
But, of course, if it hasn’t turned off yet, you’ll turn it off, then try to emergency stop.
A little annoying. I think I like the older one better where pushing a button turned it on, sent the message and turned off.
(I have 3 of the newer kind with the on/off button.)
David I have learned to look for the light. or every so often I just hit the speed button up or down just to keep it on. there is no setting that I know of. just use it and you will get use to it. I don’t eveh think about it anymore as I have gotten use to the way it works and truns it self off.