Colin's Astronomy Pages

Autostar Serial cable

The Autostar Goto computer for the LX90 and ETX range of telescopes has an inbuilt serial port to allow connection to a computer. They sell a cable set know as the #505, this cable in my estimation is overpriced for what it is, and found it simple to contruct my own cable. I'm surprised that Meade don't include this cable as standard with the Telescope.

Parts List

4 core FCC-68/Data Cable. (2 Meters)
RJ10 or FCC68 4P/4C Plug (crimp type)
Female 9 pin D Type plug
Cover for D Typre plug

Tools used

Wire cutters
Wire Strippers
Soldering Iron
Phillips head screwdriver
Multimeter
RJ10 Plug crimping tool

Assembly instructions

Use the Wire cutters to make a tidy edge at one end of the cable. Then use the wire strippers to strip 5mm from the outer sheath. Next push the end of the cable into the RJ10 plug. Make sure that each wire contact each of the four contact points. Then use the crimp tool to set the plug, and join the wires to the four contacts. It's worth taking time over this, as the better the connection the better that the cable will function.

Strip a length from the other end of the cable, about 20 mm should be plenty. Then strip 4mm from the end of each of the four cores. Now comes the important part. Study the diagram below and solder the cable so that the wires go into the same connectors. One of the wires is not used and should be cut back out of the way at the D plug end.
Wiring diagram originally posted to Mike Weasner's site by A.Jerzewski

Wiring diagram originally posted to Mike Weasner's site by A.Jerzewski

Finally secure the cover over the D plug. It's worth using the multimeter to check that all the connections work, and that there are not any short circuits.

Testing the cable.

Plug the cable into your Autostar, and the other end into your PC. Next load a comms program (such as Hyperterminal) and tell the program to attach to the appropriate serial port, and 9600bps, 8 Data bits and 1 stop bit, using no parity. Next turn on the Autostar and you should see a 'X' symbol appear. (It's used when the Autostar was at Meade Being tested) Seeing the 'X' Tells you that the Autostar is sending information to the computer. Next you will need to send a command to the Autostar to see that the cable is fully functional. Before we do that you'll need to set the date and time on the Autostar. (or just leave them as they are by pressing the mode key). Once you've passed the Autostar's inital screens, go back to the computer and type #:GVP#
The Autostar should send a readable string back to the computer. This proves that the cable is working perfectly.

Uses for the cable

Meade have periodically release new versions of the software for the Autostar. This is available from the Meade website. You can use the cable to upload these updates into your Autostar. Also there are lots of Tour's available for upload as well. Another possibility is that some asto software packages allow for direct control of the scope.

Using a product such as Skymap Pro, you can use this cable to control your scope directly. Also the AstroGPS program in the Software section will soon be able to allow you to set the Date, Time and Location directly from your PC.

WARNING: Incorrect wiring of this cable may damage your Autostar unit. I will accept no responsibility for damages occuring from the use of information from this page.

Many thanks to Richard Seymour for pointing out some errors on this page.