The Adder CATX-PS2A is a Computer Access Module (CAM) with audio support which connects to the keyboard, video and mouse ports of the computer and converts these signals to be sent over UTP cable and onto the AdderLink CATx switch. Increasingly important is the support of DDC (Display Data Channel) which allows the communication of a computers video card and the screen. Unless this communication is actively supported, as all Adder CAMs do, then the desired resolution may not be displayed and in some cases nothing will be displayed at all.
Where computers only present USB keyboard and mouse it is important to ensure that all USB functions are supported. These include 'keep alive' circuitry. It is common during periods of inactivity that a computer will occasionally send a 'keep alive' signal to it's keyboard and mouse, unless this is responded to the computer may stop and keyboard and mouse communication. Sun computers will request a 'country code' from the keyboard and unless this is actively supported some Sun computers may not work.