Celestron’s NexStar GOTO scopes use a communication protocol for various serial commands.
Please see the following:
http://www.celestron.com/c3/images/files/downloads/1154108406_nexstarcommprot.pdf
This document answers questions such as COM port settings and includes sample code.
Mike Swanson’s NexStar Resource website also has a page, “Programming for NexStar Controlled Telescopes” as a guide for those interested in developing software interfaces with Celestron scopes. It is at
http://www.nexstarsite.com/PCControl/ProgrammingNexStar.htm