There are DuoFern receivers with 6 or 10 digit radio codes. To be able to register devices with a 10-digit radio code, your central operating unit must be up to date. You can perform an update by downloading and installing the WR-Configtool under this link .
Then connect the central operating unit via USB cable to your Windows computer and read out the data with the config tool. If you then write back the data in step 8 of 8, the tool will offer and perform the update.
After a successful update, 10 digits can be entered under menu item 2-2.
If you want to register devices with a 6 digit radio code, the last 4 positions will be filled with zeros.