i have attached the tcl files that i used to control both the kramer and
the ncast.  for sure, have your student look at the rs232 interface code
that i used to control the kramer.  the damn thing is difficult to get
it do what we want.  the documentation they provide is confusing at best
and doesn't really tell you what you need to know.

for example, PIP only works where one source is video and one is RGB
even though the device has more than one video source, in fact it has
the VP-720DS has four sources since the composite and s-video inputs are
distinct, and higher version number devices have more than one RGB source.

anyway, suppose you have video in a small window on the RGB signal and
you want to switch the small window to a different video source.
internally the device allows you to do it if you use the on-screen
display/control interface.  but, you can't do it through the rs/232 or
the front panel buttons.  even when i tried to get it to do it through
the rs232 interface by sending OSD control commands, it wouldn't work.