RFD868 RTSCTS register

Hi all,

I have a working telemetry going throw a TX16s+TXMOD and a RFD868ux+Pixhawk4-mini.

Looking at the telemetry1 cable between Pixhawk and RFD868ux it seems that RTS and CTS are wired… but S13 register defaults to 0… should I enable this or not ?


As far I understand, I can probably enable it on the plane side (by setting S13=1 on RFD and BRD_SER1_RTSCTS=1 on Pixhawk) but NOT on on the TX16s+TXMOD side… is this correct ?

thanks for any advice


Nope, you should not enable it on the plane side either.
RFD has it’s own mavlink based buffer management built in, no need for flow control.

Hi Andras,

thanks for the info… I’ll keep it as is then :+1:

       Best Regards,


I do use flow control on the UAV side with 868X modules. I don´t know if there is any benefit to using it, but it does work.

Hi David, Andras…

I’ve sent and email to the manufacturer just to see if there is an official answer from their side… I’ll post the answer in case…

thanks both for the support…


Hi David, Andras…

I’ve got an official reply from RF Design… below is what they say:

[RTSCTS] is not on by default as you note. Yes flow control is recommended
the modem buffers are limited so this can help prevent data losses. It
is also best to force on the flow control setting for the telemetry port
in the flight controller settings as some flight controllers fail to
identify that it is enabled when just set to auto.

I’ve enabled it right now (S13=1 on the vehicle radio only) and BRD_SER1_RTSCTS=1 on Pixhawk4-mini… so far, it seems to work… I’ll be back in case of problems/issues.

Best Regards and thanks both for the support… thanks also RF Design for the prompt reply.