The occupancy detectors like the BD20 want to be in relatively close proximity of the track sections being monitored. The output of the BD20’s are low level circuits
and subject to electrical noise. But the NCE AIU talks to the command station via the cab bus. And the length of the cab bus back to the PowerPro command station is not that critical.
I would place each AIU unit somewhat centrally located around the cluster of BD20’s it is monitoring, and simply route/wire and daisy chain the cab bus to each
If you find that there is 1 or 2 BD20’s that end up being remotely mounted from its monitoring AIU, use a twisted pair to wire it back to the AIU to minimize
interference. [The BD20 really doesn’t need a power supply for operation. The power supply is there to only light an LED if you think you need it.]
I have a HO layout which measures 25' X 13' in a U footprint (base is 13', legs 25') and has a new terminus station which was built with block detection wired in as it was constructed, using a mix of BD20 and HDL hdM14 4-way units. The rest of the layout is
about to be rewired for block detection but due to its physical form, fiddle-yard, two through stations and mainline runs, there will be a lot (30+) of detectors scattered across the layout.
What is the ideal way to optimize the wiring back to 3 AIU-01's? Is it OK to have long runs back to a single base? Should the AIU's all be in the same place? How close to the PowerPro does the AIU-01 need to be? Ultimately the AIUs will connect back to a
laptop. Obviously, avoiding interference is a priority, while minimizing wiring runs is also desirable. Any thoughts, ideas and general rules would be appreciated. Thanks in advance,