"Hello.
Could you please help us? (sorry if this is a bit off topic)
We have a little problem last time. We make many presentation with
demonstrate our analysis work in real time. But our laboratory device
is very BIG super-power telescope and we can't install this in conference hall, also
between conference hall and Laboratory very big distance (over 100 meters).
This laboratory device connected to PC only via COM port. We have
only LAN connect between conference hall and Laboratory.
If you know about any choice to solve this, please, answer me.
Thank you."

Connect a computer directly to the telescope in your lab. Then set that computer up to network. Install a remote monitoring program like Timbuktwo or even if it is Windows XP it has that already or even Linux has that compatability. But, the answer is to connect a computer locally to the telescope then network into that computer from another terminal.