The RFD900 has the same pin sequence available on the bottom row of pins as on the 3DR radio.
http://http://code.google.com/p/ardupilot-mega/wiki/APM13DRadio -- shows the connection to a 3DR.
An off the shelf cable is available here which will directly connect the APM1/2 to an RFD900 :
Let us know if you need more information.
Would someone help me to use RFD900 for first time. This is what I have doen/seen so far:
- I connected modem via USB to computer as image in this document shows:http://rfdesign.com.au/downloads/RFD900%20DataSheet.pdf
- Another modem is connected to APM using default cable
- Both modems has solid green and air modem has blinking red
- RFD900 modem tool gives this message when I tried read settings:
-----Loading settings to port COM1-----
Connecting to COM1
Reconnecting using default Baud Rate
Failed to load settings. Please try again
- Mission planner com1 at 57600 timed out and gave message: No heartbeat packets received
- Mission planner AUTO at 57600 timed out
- Windows 7 64bit device manager shows only COM1 when AOM is not connected via USB and modem is connected to computer
I have perhaps some very basic mistake here because I haven't used any modem before.