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If you have a physical Roco or Fleischmann handset, you can point it at BigFred instead of a hardware Z21 base station. BigFred acts as a Z21 command station over UDP, and once paired your handset controls a locomotive in your BigFred roster — with full idle-brake protection.

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Compatible hardware

Any handset that speaks the Roco Z21 LAN protocol over UDP will work, including:
  • Roco Z21 multi-mouse
  • Roco WLANmaus
  • Roco Z21 start handset
  • Third-party apps and software that implement the Z21 UDP protocol

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Before you start

  • Your handset and the BigFred server must be on the same WiFi network.
  • Your admin must have enabled the Z21 server on the command station you want to use. If the command station does not appear in the Remotes dropdown, ask them to turn it on under Admin → Command Stations.

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Pairing your handset

1

Open the Remotes page and start pairing

In BigFred, navigate to Remotes in the top menu. Select the command station you want to use from the dropdown. If the command station has both Z21 and WiThrottle enabled, click the Z21 tab.Optionally choose which vehicles the handset is allowed to control:
  • Toggle Allow all vehicles to give the handset access to your whole roster, or
  • Type vehicle names in the Vehicles field to restrict access to a specific set.
Set the Handset brake seconds value if you want a longer or shorter idle timeout (6–60 seconds).Click Generate Pairing.
2

Note the pairing code

BigFred enters pairing mode and displays a pairing code in the format:
The code is shown as both a CV3/CV4 pair and the equivalent function-key sequence. You have five minutes before the pairing window expires.
If your admin has enabled IP stickiness on this command station, any connection from your IP address is automatically paired without requiring you to enter a code. In that case BigFred confirms the pairing as soon as your handset connects.
3

Configure the handset network settings

On your Z21 handset, go to its network or command station settings and enter:
  • IP address — the IP address of the BigFred server on your local network
  • Port — 21105 (or the custom port your admin configured)
Save the settings. The exact menu path varies by handset model — consult your handset’s manual if you are unsure where to find it.
4

Enter the pairing code on the handset

After the handset connects to BigFred, it will prompt you for a pairing code. Enter the CV3 and CV4 values shown in BigFred, or use the equivalent function-key sequence displayed on screen.BigFred recognises the code and links the handset session to your account. The status chip on the Remotes page changes to Paired.
5

Select a locomotive and drive

Your handset is now paired. Select any locomotive from the handset’s address list — BigFred will route it to the corresponding vehicle in your roster. Speed, direction, and function commands flow through BigFred to the DCC bus.

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Session expiry and idle brake

Your handset session is valid as long as the handset keeps sending UDP traffic. If the handset goes idle for longer than the configured handset brake seconds, BigFred brakes the locomotive and marks the session as idle-braked. To resume, reconnect your handset and repeat the pairing process.
Moving out of WiFi range or switching to a different network will trigger the idle brake. BigFred brings the locomotive to a controlled stop.
If IP stickiness is enabled, BigFred shows an approximate session expiry time in the Connected Clients table. When this time passes, the session is cleared and you will need to re-pair.

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Unpairing

To end a handset session manually:
  • On the Remotes page, click Unpair while the session is active, or
  • Find your entry in the Connected Clients table and click Unpair next to it.
BigFred immediately releases the handset’s throttle slot and the locomotive stops receiving commands from that handset.