I do not have a serial port to connect my scope to a PC, but I do have a USB port. How do I connect NexRemote with my scope?

You will need a USB to RS-232 adapter cable, Celestron model #18775, or its equivalent. As of mid-2012, the #18775 is no longer available.

Here are two adapters recommended by Celestron (in the aftermarket):


  • TrendNet TU-S9 (available from Amazon.com). It uses a Prolific chipset.

  • KeySpan USA-19HS (available from TrippLite or Amazon). It uses a Texas Instrument (TI) chipset.

Both adapters work with operating systems Windows 7 (64-bit), Windows XP (32-bit) and Mac OS X 10.7 Lion. Both adapters work with MCupdate, HCupdate, and the new Celestron Firmware Manager (CFM) on all 3 operating systems. Most needed drivers are located on the supplied disks with the adapters; however, you may need to visit the manufacturers' websites for the most current drivers (for example, Mac OS X Lion).

The Keyspan is a more expensive adapter, but it provides the following useful features:


  • Detachable USB cable. (This allows you to buy a separate cable that is as long or short as you need.)

  • Status lamp. Glows steadily when there is power, blinks when the drivers connect (ready to use) and blinks faster when there is traffic on the serial bus.

  • KeySpan serial assistant software that links up to the driver. Shows detailed diagnostic data and provides self-tests, shows all RX and TX traffic (HEX or ASCII modes) on the serial bus at any baud rate, shows setting changes such as baud rate and even DTR/DSR/CTS/RTS. All of the above information can be logged (saved) for later use as well.

Assigned COM port number does not change when the adapter is plugged into a different USB port.

Updated 12/14/13