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SPROG IIv3, SPROG IIv4, SPROG3 and SPROG Nano Windows USB Driver Installation Instructions

Note: for Windows 7 or Windows 8 or Windows 10 users, see those instructions.

On versions of Windows including XP and Vista, when the SPROG is plugged in,
the device is recognized by the computer, and the "Found New Hardware Wizard" will start up.

Specific drivers are needed for SPROG to function correctly.
All required drivers are included in the CD supplied with SPROG, and are also available to download at

For each model, a different driver set is needed. Check the name on the SPROG for the correct version:

  • For SPROG II, follow the SPROG II instructions.
  • For SPROG IIv3 or v4, you will use the sprogIIu package (see below).
  • For SPROG 3, you will use the SPROG3 package (see below).
  • For SPROG Nano, you will use the S-Nano package (see below).
You can also download the current drivers from the SPROG DCC download page. These are compressed "zip" files and will need to be extracted by Windows, or a third party "zip" program.
To uncompress these files, find them (probably in your "Downloads" folder) using the File Explorer, and then point to the item and double-click.
Depending upon your Windows version, this will open the compressed zip file and show a single entry with essentially the same name as the compressed file. Do not double-click that; instead drag it out of this window onto an empty space on the Desktop (background) of your screen, where it will be easy to find in the next step!
You will briefly see a small window telling you that Windows is uncompressing the files.
(Alternatively you can right-click on the zip file. Depending upon your Windows version, the menu will show an "Extract all..." entry, which you should select. Then click on Extract at the bottom of that pane, and the files will be unpacked into that same location, where you will need to find it in the later steps.
If you do not have this menu item, you may need to install a 'zip' program to unpack these files.)

USB Drivers

You will follow this sequence through to completion, and then check for the assigned COM Port.
This installs the USB Port driver with USB-serial interface that presents the USB connection as a serial "COM" connection for JMRI to use.

Click "Install from a list or specific location" then "Next >".

Click "Search for the best driver in these locations" then
"Include this location in the search" and then click the Browse button
to find the driver directory on the CD-ROM supplied with SPROG, (or the location you used if you downloaded drivers).

  • For SPROG IIv3 or v4, select D:\USB\sprogIIv3
  • For SPROG3, select D:\USB\SPROG3
    For SPROG Nano, select D:\USB\S-nano

Click "Next >".

The wizard will take a short time to find and verify the drivers in this location.

The base drivers are fully compatible with WindowsXP and newer versions, and those supplied on the CD are the latest drivers. To make them SPROG device specific, the .inf files have been custom configured, which surprises Windows, and causes this dialogue to appear. The drivers we supply are correct and are perfectly safe to use.
Click "Continue Anyway".

Click "Finish".

Important! SPROG Windows USB Driver Identification

The Virtual COM Port (VCP) drivers that you have installed connect to the USB port and cause the SPROG to appear as though it has connected via a normal COM (serial) port.
Windows automatically assigns the COM port number during installation.
You must now identify which port is assigned to correctly configure DecoderPro.

Start the Windows Device Manager by right clicking "My Computer" on the Windows desktop and selecting properties.

Select the "Hardware" tab and click on "Device Manager":

Click the "+" next to "Ports (COM & LPT)" and note the COM port number assigned to SPROG Decoder Programmer. In the example below, COM3 has been assigned.
This COM port must be specified in the DecoderPro preferences (next step) to allow DecoderPro to communicate with your SPROG.

Start DecoderPro

The next step is to start DecoderPro, and set preferences for this connection.

Next an introduction to DecoderPro.

BBM Group LLC, Waldport OR 97394, USA
Last updated 6th March 2021, rev 46
(C) Copyright 2006-2021 SPROG DCC & BBM Group LLC