8-Button Control Panel Wall Plate with Programmable LED Buttons, RS-232, RS-458, Relay and IR Control (JTD-P8)

So what kind of cable goes between this unit and an hdmi matrix? Rs 232 cable in the package has one end serial

Can I connect more than one of these to a device? I'd like to use them with a matrix switcher, but have need for two remotes.

So after it’s programmed, what cable do I use to connect with a jtech hdmi matrix?