Eddie from Australia wrote me recently to tell me about his success using a serial-to-bluetooth adapter to connect his Digital Setting Circles board to his laptop (avoiding the serial cable which is an obvious tripping hazard, especially in the dark during an observing session). Eddie is using the SENA Parani-SD 200 serial-to-bluetooth adapter connected to the DSC board, and the SENA Parani UD100 USB-to-bluetooth adapter with his laptop.

Eddie wrote:


I have finally managed to get the Bluetooth connection working with your interface and Cartes du Ciel. I will let you know what I had to do and the setup I’m running so that you can let other people know if you get asked the question.

Program: Cartes du Ciel
Serial Bluetooth adaptor: Sena Parani SD200
USB Bluethooth adaptor: Sena UD100

Information for the Bluetooth adaptors can be found on www.sena.com

You have to plug the SD200 into a computer with a serial port in order to set up the adaptor. The adaptor gets set to mode 3 with command response set to on. Using the Dip switches on the SD200 the Baud rate and flow control can be set to 9600 and off respectively, the other parameters are set at the factory and cannot be changed. When connecting the Bluetooth adaptors the UD100 will need to be forced to operate on one of the local com ports i.e. 1,2,3…. etc so that it can work with your interface.

Then I had to make up a null modem serial adaptor between your interface and the SD200 adaptor. Pins 2 and 3 have to be crossed over in the connector and 5 is straight through. Cartes du Ciel doesn’t like handshaking and therefore the remaining pins must be left off or the tracks on your PCB have to be cut.

Once all of this is done your interface works very well and the laptop can be setup remotely from the scope so that wires aren’t being tripped over or having to attach your computer to the scope itself.

I hope that this information will help you and any other Astro nuts out there setting up their interface with a Bluetooth connection.

Thanks, Eddie, for passing on that information.

I’ve heard of other users who’ve successfully used similar devices, especially those from AirCable. I don’t have any personal experience with any of these devices, but they’re an occasional topic of conversation in the Yahoo Groups’ PalmAstro group. I’d welcome any and all reports of other bluetooth adapters being used with my DSC system–just leave a comment below.

One thought on “SENA Bluetooth Adapters with Digital Setting Circles

  1. Hi Dave!

    End of 2004 I have build your DSC and adapted it onto my 10″ starsplitter dobsonian. Thank’s again for your development.

    Since nowadays serial connections are more and more less common I wanted to switch towards bluetooth. There is a cheap bluetooth-serial adapter available here in Germany – the Pico Plug (less than 20Euros – search ebay, but beware, somebody sells them in 1000+ quantity). It contains both, a serial and a parallel interface.

    And it works fine together with your board and Dough Braun’s recent palmdsc (now supporting bluetooth, too).

    [To get the Pico Plug running first you have to update its internal firmware, then you have to configure its serial line to run at 9600baud. Both can be done by a Windows program if the Pico Plug is connected to the serial line of your PC. That even worked for me using Linux/wine and a serial-USB dongle.]

    Hope that hint might help somebody – regards,



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