With this 2-channel module you can detect occupation of two blocks of track on a DCC layout. Each detector works by passing the DCC supply to the track through a current transformer and will detect currents as low as 1 mA (1/1000 Amp) with adjustable threshold. Two channels are provided so that two blocks of track can be accomodated.
You can display the status of the 2 channels using Wifitrax WFD-60 Layout controller that polls all similar modules frequently to display the track occupation on a WFD-60 Panel. The WFD-60 will give you up to 8 panels on which you can draw plans of your layout and see block occupation as well as control turnouts, signals and lights.