EM540 - 2 or 3 wire?

Hi,

i’m currently thinking about replacing my Fronius Smartmeter with a EM540, to get faster readouts without having the Fronius Inverter + it’s Json API in between.

The EM540 uses RS485, combined with the original Victron RS484-USB-Connector the manual says to connect D+, D- and GND.

Now, I have plenty of RS485 USB Serial Converters around, that only have a D+ and D- Connector.

  • First question would be if the meter / communication will work with 3rd party RS485 Dongles “out of the box”, or if there is plenty of headache to get the configuration done. (For the original victron converter it says “Plug & play”)
  • Second question is, if the GND for the Meter is required at all - and if yes, if it is sufficent to pull the GND from the cerbos Supply-GND rather than from the USB-Port hosting the RS485 Converter. (Would assume they are “same level”, but you never know)