Hi Jimbow,
I've watched the specifications of the receiver FRSKY D4RII.
It differs from Orange R615X in 2 points:
1/ The synchronization is based on falling edge.
2/ The frame rate is 18ms. So the max number of servos is restricted to 1st 6 of 8 channels (as explained in last red note of manual).
It's why my CPPM library can't synchronize with FRSKY at moment.
I must write some modifications to my library.
At moment, I doesn't own a FrSky equipment, only Orange receivers and Spektrum transmitters.
If somebody based in Switerland can lend me a FrSky D4RII and a transmitter, I could update my library.
You can also try another library, for example:
https://github.com/claymation/CPPM