Thanks for adding the references, @glyn.hudson and @toadhall.
I would add that 1) @pantherale0 has recently added some more options to his excellent HA Integration, and 2) @PeterX has recently improved his (also excellent) NASAmonitor software (Samsung ASHPs: Review of NASAmonitor – an Alternative to SNET-Pro2). Neither of these approaches requires a MIM-B19N (at ~£180 a pop, they are hard to justify).
Are you looking for more information than is available by simply using SNET-Pro2/NASAmonitor? The former may be a bit clunky but allows you to change your FSVs from the comfort of your laptop and get details of the Outdoor Unit (as well as Indoor) operating parameters; the latter is aimed mainly at Indoor info, but is much more visual. All you need for either is a (low cost) RS485-to-Ethernet adapter (per Glyn’s reference above). The same device can also get the serial data from the MIM into HA using the above Integration (and no Modbus programming required at all 
).