Digitrax RX4 | Block Transponding Receivers

Block detection tells you a section is occupied. Transponding tells you which locomotive is standing in it. The Digitrax RX4 is the receiver that makes that possible: four transponding zones per board, reading the low-current pulses sent by transponder-equipped locomotives and cars, so the system knows not just that something is there but exactly what.

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• Four transponding zones per RX4 - identify which locomotive or car is in each zone, not just that the zone is occupied.
• Low-current pulses that do not interfere with DCC decoders or other track signals.
• Works alongside your existing occupancy detection, adding identity to the detection you already have rather than replacing it.
• Compatible with most DCC systems, and adaptable to a range of layout wiring arrangements.
• The foundation for automatic routing, dispatcher displays and computer-driven operation that needs to know which train is where.

What is the difference between detection and transponding?
Occupancy detection reports that something is drawing current in a block. Transponding reports which decoder address is there. If you want a dispatcher panel or a computer to route trains by identity, you need transponding.

Do my locomotives need anything special?
Yes. Transponding only works with transponder-equipped equipment - either a decoder with transponding built in, or a separate transponder fitted to a car.

Will the pulses upset my sound decoders?
No. Transponding uses low-current pulses designed to sit alongside the DCC signal without interfering with decoders or other track signalling.

Does it replace my block detectors?
No, it complements them. Many layouts run both, using occupancy detection for the basic signal logic and transponding to identify what is in each block.