Hints and Tips

Building an RS232 Cable for a Magellan I/II or LX200

Some versions of the Meade manuals which describe how to build an RS232 cable for attaching a Magellan I/II or LX200 to a PC can be confusing. The main confusion is over the pin numbering for the 6 line telephone jack (RJ-11). To help avoid confusion I have drawn a diagram of how I wired up an RS232 cable for my Magellan I and LX200.

Finding which pin is which on the DB-9 is much easier. As you look face on at the connector you will see each hole has its pin number embossed next to it. Please note that the colours of the wires in the diagram above are used to make it easier to see which pin on the RJ-11 is connected to which pin on the DB-9 and are not intended to represent the colours of the wires that you may see attached to your RJ-11 in these pin positions.

For completeness, the following table defines how to connect the RJ-11 to either a DB-9 or a DB-25 connector.

RJ-11 Pin Number


DB-9 Pin Number

DB-25 Pin Number

1 Not Used Not Used Not Used
2 Not Used Not Used Not Used
3 PC Transmit Data 3 2
4 Ground 5 7
5 PC Receive Data 2 3
6 Not Used Not Used Not Used

I must thank Pat Hensley for helping me get to the point where I could put this page together. Without his advice I would almost certainly have wired my cable up the wrong way round.

I have made every effort to ensure that the information on this page is correct, but I can accept no liability for any damage caused to your equipment as a result of following my advice!.