I have a very old Meade ETX-125EC telescope in excellent condition. There have been no firmware updates to the AutoStar 497 handset because an old copy of Windows XP is required for the upgrade.
I purchased a SkyFi 3 adapter so I could use SkySafari 7 Plus on my iphone and iPad to control the scope. The SkyFi 3 is the device that allows a WiFi device to connect to the serial port on a Meade ETX scope.
I could connect by WiFi to the SkyFi 3, but the serial connection to the scope kept failing. I checked to make sure my RJ11 cables was correctly plugged into the serial port on the 497 handset. I had a collection of DB9-RJ11 adapters and 4-pin RJ-11 cables but none of them would work.
I contacted Meade and they said there is no more support for the older Meade ETX's but to their knowledge there are no known ETX's that will not work with a SkyFi 3.
So I naturally figured that the serial port in the SkyFi 3 was bad. I spoke with Mike in Customer Support at Simulation Curriculum. His first thought was that it was my serial cable. I didn't agree because I had plenty of experience years ago with serial adapters. So I ordered a second SkyFi 3 and a new Meade cable provided they would test them as a working unit before sending them out.
In the meantime, I got all my DB9-RJ11 adapters and cables together and started trying various combinations. Lo and behold, I got one to work! It WAS the cable that was the culprit!
The problem with DB9-RJ11 adapters is that you cannot assume the internal wiring is correct for this application. Sometimes the transmit & receive lines are reversed, sometimes is a CTS line that's at fault. None of my adapters had labels on them so you can imagine my frustration. I blamed everything, the scope, the SkyFi 3, everything except the serial cable ...
THE BOTTOM LINE
Buy a new serial cable from Curriculum Simulation or Meade. They're pricey but they are tested! All these cables look alike but they are NOT all alike internally.
Hope this helps!