Chris,
From page 95 of The DCS Companion 3rd Edition:
Providing Power to the TIU
Like any other electronic component, the TIU requires a power source. MTH designed the TIU so that it can be powered in two different ways.
One way is to use the track power that is present at the inputs to TIU Fixed Channel #1. This power source is
available whenever the O gauge operator is running trains on tracks connected to Fixed Channel #1.
Another way to power the TIU is to use a separate power supply that is plugged into the TIU's Aux. Power port. In this case, the TIU would have power all the time. Any power supply that provides between 12 and 22 volts AC or DC at 1.5 amps or greater, equipped with a compatible barrel plug, may be used.
If the TIU is a Rev. L (or later) that has a USB port, the TIU may alternately be powered via the USB port. However, this should only be done when using the TIU solely to update TIU or DCS Remote software. In order to perform DCS engine sound file transfers, DCS Remote backup or recovery, DCS engine operation, or activation of switch tracks or accessories connected to a TIU's AIUs, power must come from either the Aux.
Power port or Fixed Channel #1 Input.
When the TIU is powered through Fixed Channel #1 Input, every time the power to the tracks controlled by Fixed Channel #1 is interrupted for any reason, the TIU turns itself off. However, when the TIU is powered through the Aux. Power port, the TIU remains turned on regardless of the state of power applied to the tracks controlled by Fixed Channel #1.
This and a whole lot more is all in MTH’s “The DCS Companion 3rd Edition", available for purchase from many fine OGR advertisers and forum sponsors, or as an eBook or a printed book at MTH's web store!
