Originally Posted by F1 Rocket

A few notes on how the Cortex Pro (CP) handles (2) Jeti RX in the serial I/O mode:

CP ports B and 6 are the only bidirectional ports. Therefore telemetry coming back from the CB only has this path back to the RX. This is why your primary RX should be connected to CP port B and CP port 6 should be connected to CB port RX1.

The data output from CP ports 5 and 6 is the same. But remember that only port 6 is bidirectional.

CP port A is the secondary RX port. The CP uses the input on port B until data is lost, then switches to port A. It can stay on port A for up to 4 seconds before switching back to port B. This delay is variable but the important thing is that since only port B is bidirectional you could lose the telemetry from the CB (and all sensors plugged into it) for up to 4 seconds. Note that only telemetry is lost. You will still have control. This could and has caused some issues if you are for example using a MBar for gear failsafe, a MSpeed for gyro gain control, or an engine telemetry module for a flameout alarm.

Prior to the release of the EX Bus Backup/Input feature in the REX receivers the only way to use (2) Jeti RX with the CP was to use ports A and B. But as I said before, this caused some telemetry issues. Now that we have the REX available there is no need to use port A. Simply plug the 2nd RX into the REX and connect the REX to port B. But......there is a catch when doing this. The CP learns the input signal and output mode types by detecting the input on each port. In order to use the CP in the serial I/O mode it must see an input on port A. This means that when using (1) RX you must first connect it to port A and go through the input signal programming. Then move the RX to port B and complete the rest of the setup.