Troubleshooting Serial and USB
Laptops in particular can be a little tricky with the serial port.
NexStar Observer List (NSOL) uses the most straight-forward method possible
for communicating via the serial port, so if you are having problems with
NSOL, other programs will experience the same problem. If you can get
NSOL working, but not your other programs, visit their web site for any
updates and/or contact their technical support. Here are some things
to try to get your PC and scope communicating:
- The telescope must be aligned before it will accept commands.
To test indoors, simply perform a Quick Align or an Auto Align,
accepting the locations pointed out for the two stars.
- NSOL and almost all other astronomy programs can only
communicate with the telescope via the port on the bottom of the
hand control - not the ports on the base of the mount.
- Perhaps you selected the wrong telescope type in the program;
you will not harm your telescope or computer testing other scope
- Some combinations of computers and Celestron telescopes are
sensitive to the order of events when connecting the two. Try
aligning the scope with the PC disconnected from the hand control.
Then connect your computer and start your astronomy software.
- Be sure there are no other programs using the serial port, such
as synchronizing software for various specialized hardware devices.
- Try other 'Comm Port' settings. In NSOL communication port
settings are found in the Tools, Setup menu.
- Check to be sure the driver is loaded for the USB hand control
or the USB serial adapter. With the cables all connected:
- In Windows, open Control Panel (usually on the Start menu)
and open the System icon. Click on the Device Manager. Click the
+ next to 'Ports (COM & LPT)' to show the actual ports. At least
one of the ports should be labeled 'Communications Port (Com1)'
or perhaps Com2 or other. If the little icon next to this entry
has an X through it, you must double-click the icon and try to
determine why the communication port is not operating. If no
communication ports are listed, the drivers are not installed.
Note that you can disconnect and reconnect the cable from your
computer and watch devices disappear and reappear in real time.
Manually install the drivers from the CD that came with the
adapter or for the USB hand control download the drivers from my
- In Mac, run the System Profiler program under the
Applications-Utilities folder. Click USB hardware inside System
Profiler and look for “USB-Serial Controller”. Note that you can
disconnect and reconnect the cable from your computer and watch
devices disappear and reappear in real time. If this is missing,
the drivers are probably not installed. Manually install the
drivers from the CD that came with the adapter or for the USB
hand control download the drivers from my website
- For Linux, the methods for checking serial ports are
numerous. Try searching the Internet for your version of Linux,
for example "Red Hat serial ports".
- If you are using a USB to serial adapter, it must provide a true
serial port. Some adapters are HID devices - such adapters are
designed for "human interface devices" only, in other words, you can
connect a mouse to such an adapter but not a telescope. I
recommend you purchase Celestron's own USB to serial adapter
(Celestron part number 18775) or an adapter that specifies it uses
either a "Prolific" or "FTDI" chipset.
- A faulty cable might be the problem. One way to test the cable
is to install NSOL on a standard desktop PC with an actual serial
port and try controlling the scope from there (remember the indoors
alignment from number 1 above). Also, be sure it is for Celestron
telescopes. For example, the control cable for Meade telescopes
appears to be identical but the pin connections are different and
the cable will not work on Celestron telescopes.
- Take a good look at the connector on the bottom of the hand
control - insure none of the pins appear bent or misaligned.
Hopefully one of these tips will resolve any issue you have.