Since the unit can accept grid power via the barrel connection can it be configured to report/monitor if shore power is present?
The easiest way to monitor shore power is generally to connect the output power from any adaptor/transformer to one of the input voltage connections. You can then see voltage levels on the website and/or set an alert for any time the voltage cycles on or off.
How does this work if an AC transformer doesn’t share a negative voltage connection with the battery system?
This depends a little on the details of any particular setup. Often the shorepower system will have a DV output (where it might be used to charged a house bank, for example). A connection there with a diode for isolation will let the device sense when DC power is being supplied from the shorepower. We can provide more details if that’s relevant for your setup.
If there’s only a 120 Volt supply, then you can use a good quality AC/DC transformer to have your FloatHub sense when that transformer is supplying Dc power. You do need to tie the ground of that transformer to ship’s ground, but that is quit common (that’s really what a DC charge system that is powered by shorepower AC is doing).
Of course let us know if any of this is unclear or if you have any other questions.