The BKM-10R is a remote controller for several of Sony's BVM monitors, notably excluding the BVM-A series, which use the BKM-15R. The BKM-10R connects to the monitor through DE-9 plugs, utilizing RS-422 as the physical cabling. This connection also supplies the controller with power (5V DC). The controller can control a single monitor, or several daisy-chained monitors.
While the controller is generally available, there are several projects aiming at replacing it at either reduced costs, with added functionality or simply for DIY'ers. Examples of these are:
Aaron Bonhams BKM-10Replacements project(s) found here, which includes the "BKM-10Rp2040" project which allows for controlling the monitor by an IR remote.
Andy Gatzas EmuBKM-10r found here written in Python to be able to be run on most PCs, requiring a USB->RS422/485 adapter.
Martin Hejnfelts BKM-10Rlternative found here which aims to recreate the complete functionality on a custom PCB.
Matthew Holders BridgeCmdr found here which also aims at controlling other devices like A/V switches, through Raspberry Pi.