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RFD900 Link

Posted by Sean Whitney on March 27, 2013 at 2:26pm

Having trouble with TX and RX from my autopilot. I am using the RFD900 link which has 5 wires ground, positive, RX, TX, and CTS "Clear to send control input".

My autopilot only has ground, TX and RX. I think my problem has something to do with the CTS wire. Does anyone know how to bypass the CTS wire? Also in the 3DR program is there a way to turn off flow control?

Here is a link to what I am playing with.

http://rfdesign.com.au/index.php/rfd900

Here is some more wiring stuff

http://www.ftdichip.com/Support/Documents/DataSheets/Cables/DS_TTL-232R_CABLES.pdf

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Replies

  • Seppo March 31, 2013 at 5:56pm

    Hi Sean,

    The RFD900s and 3DR radios are preset with flow control turned off.

    The only connections that are needed for both are, GND, TX, RX, +5V

    Things that are worth checking out are to see the green link LED is solid on both sides - if it is flashing, it means that the radios are not connected to each other.  Also, to check that the red LED is flashing on both ends - this shows data traffic flow on both ends.

    The serial port is on 3DR and RFD900s is also set by default to 57600, n, 8, 1..

    TX and RX always have a way of ending up switched, no matter how carefully they are checked (ask any electronics engineer ! :) ) -- you can try swapping them if you are using your own cable harness.

    Hope it helps a little !

    • Mike Carswell > Seppo February 20, 2015 at 6:25pm

      Hi Seppo,

      I'm having a few dramas with my RDF900 units. One seems to be good and I'm able to 'load settings' from Mission Planner and connect to the 'RFD Modem tools' software okay. This flashes the green light when connected to either my computer via mini USB or my pixhawk via my home made cables. 

      The other radio however has a solid red light whichever it is connected to, and is unable to 'load settings' through Mission Planner or 'enter command mode' through the RDF900 software. 

      I have looked everywhere for what a solid red light means - perhaps all light codes should be a part of the user manual. 

      Cheers,

      Mike

      • Mike Carswell > Mike Carswell February 20, 2015 at 7:00pm

        Ah don't worry have sorted it.

        I saw on some site talking about 3DR radios what all the light codes are. Solid red on them means a firmware related message. I figured it might be the same on this so updated the firmware using RFD modem tools software and it was successful. She's come right now and they've both gone a nice solid green. Hope this helps others with the same problem in future.

        Cheers

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