How to build a serial cable for Celestron NexStar telescopes.

Preparing the cable

Prev: Introduction - Next: The serial connector
[-] This is the plug you can find at the bottom of the keyboard. Once we connect the computer here, we will be able to send commands and receive the current position of the telescope.

RJ plug at the bottom of the keyboard

[-] We need a cable, just like the ones used to connect a receiver to the telephone. It has a coiled cable which is useful when you have to move the keyboard or the computer.

Phone coiled cable

[-] This is the detail of the cable's plug. Note there are 4 connectors each one with a colored wire.

Detail of the cable's plug

[-] As every cable has different colors, in the following descriptions we will call each wire with a letter, starting with A for the wire at the left, then B, C, D as in the following diagram:

Diagram of the RJ plug

[-] We now have to cut away the plug at one end of the cable, so we can solder a serial connector.

Cutting the plug

[-] We need to peel the wires in this way. Pay attention, this is a rather difficult process, as those wires are very thin and easy to cut. Note the "B" wire won't be connected so it's cut shorter than the others.

The cable is cut and the wires are peeled

Copyright (C) 2003 Alessio Sangalli,

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