RS232/COM port
Use a Voltronic USB RS232 cable cable plugged into the inverter port labelled "RS232" or "COM" which is located at the bottom of the inverter.
Steps in SolarAssistant
On the configuration page, select "Voltronic" as your inverter model.
Select the USB port(s) where you have Voltronic inverters connected.
Click connect:
Parallel installations
With Voltronic inverters you only need to connect one inverter to read all parallel inverters regardless of which monitoring port is used.
If you have a parallel installation but all inverters are not showing in SolarAssistant, then check if their serial numbers are perhaps exactly the same by connecting one inverter at a time and going to the settings page. If their serial numbers are the same, then each will have to be connected with it's own USB cable.
Troubleshooting
If you have any issue, please try the official WatchPower or SolarPower application from a laptop. If it works with these official applications, then it should work with SolarAssistant.