The FN IAR is based on the SCAR. It has a rate of fire of 650 RPM and weights in at 10.4 lbs.
One very interesting features is that it switches automatically from closed bolt to open bolt depending on the chamber temperature. From FNH-USA:
Today FN offers the new Infantry Automatic Rifle (IAR), a unique, highly-adaptable, modular selective fire weapon system that fills the roles of both individual battle rifle and squad automatic weapon in one light, compact package. The magazine-fed FN IAR is capable of firing from a closed bolt in both semi-automatic and fully-automatic modes, yet automatically transitions into open-bolt operation in semi-automatic or fully-automatic before reaching cook-off temperature for a chambered cartridge.
I do not think the temperature switch would be electronic. Most likely there is a piece of metal that expands when heated and causes a switch from closed to open bolt.
Again, a bit thanks to Daniel Watters for pointing this out to me.Related