The Heart of the Fronius DATCOM System. The COM Card is communications hardware that is installed directly into your FRONIUS inverter in the same way a Plug-n-Play card is installed in your PC. Every inverter needs a COM Card in order to communicate to the Datalogger to allow you to receive your data. Fronius IG Solar Inverter Interface and power supply option card for aftermarket installation of the DatCom data communication system;DatCom System requires one COM Card per Fronius IG inverter and one Datalogger Box per DatCom System. Features an internal plug-in card for data communications.