It's just a 2 amp, 2 pin 28 vdc connector that was probably for some sort of accessory (no telling what) It would be of more use if converted to a standard cigarette lighter port or just eliminated if you already have one.
What makes this really unusual is the off-centreline contact location.
Every 2-pin connector I have ever seen has the two pins symmetrically located.
Can anyone recognise this 2-pin circular connector
I have asked Positronic and they don't recognise it.
The aircraft is a Diamond DA40-180, made in Canada I believe, about 10 years old.
Normally there would be a keyway.
Relying on the pins to polarise the connector is dodgy, because they will get broken very fast.