modelrailsim.comModel railroad simulator
Real controller

Your handset drives the simulator.

A small dongle connects to the track and listens to every DCC command, including the ones from your handset, and passes them to the simulator. Turn the knob on your real throttle and the loco on screen responds. Works with any DCC system.

What you need

  • The modelrailsim DCC Sniffer, coming to the store: USB-C on one end, two screw terminals for the track on the other, about $29.
  • Or NCE's DCC Meter/Analyzer, part 524-0326, about $80 to $100 at NCE dealers. It works with the simulator today, on any brand of DCC system, and doubles as a track volt and amp meter.
  • Two wires to the track, or to the track terminals on your command station's panel. Alligator clips, or a Kato terminal joiner with the plug cut off.
  • Chrome, Edge or Brave on a computer.

Wire it

  1. One wire from each of the dongle's terminals to the two rails, or to the panel's two track terminals. Either way round: DCC is AC, there is no plus or minus.
  2. USB-C from the dongle to the computer. The dongle listens only, through an optocoupler, so it can't harm your command station or your decoders.

Connect

  1. Open the simulator and the Real layout card: Shift + H.
  2. In Real controller, press Connect sniffer and pick the dongle's port. The status line shows packets arriving once the layout is on.
  3. Add your real locos by DCC address under Real locos, if you haven't. The handset's speed, direction, bell, horn and turnout throws now show on screen for those locos.
  4. With the NCE USB Interface connected as well, both throttles are live: the screen drives the layout and the handset drives the screen, and nothing drifts.

Good to know

  • A new dongle, or a plain ESP32 board, gets its firmware from the card: Install firmware…, pick the port, done. No other software.
  • The sniffer only reports changes, so a quiet layout is a quiet log. Turn the knob and the line appears.
  • Turnout throws from the handset show on the plan when the turnout's accessory number is set under Real turnouts.

If nothing arrives

  • Connected, no packets. Track power off, or the wires aren't on the rails. The P line's count should climb every five seconds while the layout is on.
  • Garbage in the log. The wrong speed; the card switches to the other by itself after a moment. If it doesn't settle, unplug and reconnect.
  • Many bad packets. A loose wire on the rails. Clean the rail and clip again.
  • The dongle shows a port but never says hello. It has no firmware yet: press Install firmware….