PC Port Cable for Celestron Scopes
A cable can be connected from the serial port of a computer to the PC Port on the base of the GPS, CPC and CGE telescopes. The same cable can be used with the AS-GT, CGEM, NexStar 5i/8i, NexStar SE and NexStar SLT with an optional Auxiliary Port Accessory Kit (part number 93965) from Celestron. The two uses of this connection would be to run NexRemote without the use of the real hand control and to update the motor control firmware in the mount. See Firmware Versions on this web site or the Support section of Celestron's web site to see if newer firmware is available for your scope.
The PC port on the base of the scope is a standard RJ-45, so it is fairly easy to build a cable using a flat RJ-45 cable and a DB-9 (female) to RJ-45 adapter. The following is the end of the cable that plugs into the PC port on the scope. Insure that the leads indicated connect to the correct pins on the DB-9 serial port connector shown below.
DB-9 End of PC Port Cable
DB-9 to RJ-45 adapters and RJ-45 cables can be purchased at http://www.a2zcables.com (search for "db9 rj45" for the adapter). The picture below shows a typical adapter. Pre-built cables are sold by most Celestron dealers under the name "programming cable". David Carter sells pre-made cables online for a much lower price than you will usually find - www.astrogadgets.com.