We take great pains with EAM to, as much as we can, support older versions on the same major version, and when it makes sense/is possible, even the previous major version.
That is, I'm pretty sure an upgraded EAM controller is basically fully compatible with all 8.1.x releases (and probably 8.0.x, but hopefully you don't have any of those) and at least some functionality is available to connect to 7.9.recent versions.
This general strategy will continue into 8.3, where full compatibility will be available with other 8.3 gateways and "best effort" will be available to 8.1. 7.9 to 8.3 will not be supported.