Hi, Hervé!
So you understood it right that there are two cables to update MULTIPLEX-devices: # 85148 ist the right one to update the software of the ROYAL (from evo/pro to SX).
Now inbetween the different updates MULTIPLEX felt the need to improve the HF-module's firmware and this is a separate device, so not part of the main software of the ROYAL and therefore you need a different cable - # 85149.
So how do you do it? You have to link cable # 85149 to the HF-modul at the right-hand top
Your HF-module may have a lable which is a bit different not showing the com-sign. That does not matter but the photo shows how the cable is to put an correctly.
Then connect the # 85149 to the PC, open the launcher and switch on the radio. Normally the launcher is to recognise the module automatically and thus offers the menu showing the update option.
Good luck!
w/r
profimc