Tacx has adopted the ANT+ FE-C standard for their Smart line of Trainers (the Bushido Smart and the Vortex Smart , along with their Tour de France versions). This new development allows Zwift to control resistance on these trainers in addition to reading their wattage output.
In order to take advantage of this, you will need to update the firmware of your Tacx trainer through the Tacx Utility App (_ iOS devices only _) and follow these steps:
Before beginning the update process, turn on Bluetooth in your settings.
Open the Tacx Utility App. Your trainer will appear on the main screen. Select it.
The Utility app will detect your current firmware version and give you the option to upgrade to version 3.1.7 or newer. Tap “Upload firmware” to begin the process.
After the upload completes, a completion message will appear. Unplug the power cord as directed, and then plug it back in.
The update is complete! If you want to confirm that the update completed, you can click on your trainer from the app again, and you’ll see that the firmware version number of your trainer will match the version number of the update.
You can now close the Tacx Utility, pair your Tacx Smart trainer with Zwift, and experience automatic resistance changes.