In a discussion with Castle tech support, I was told:
"The Telemetry Link will not work if the ESC is programmed for Multirotor or External Governor Mode due to the higher PWM frequency."
"Telemetry Link" is a product that Castle sells:
http://www.castlecreations.com/en/accessories-5/telemetry-link-for-sbus2-010-0152-00I am not using this product. I am using the Spirit cable, and I suspect it provides the same function, but not sure about this.
I am using Multirotor (vehicle type) in the ESC so that the Spirit gov will have immediate control over the ESC. I am now wondering if there is an issue with using the signal wire to transmit both telemetry information and throttle signal. On all my Castle ESC's, I have experienced no issue beyond my transmitter notifying me (I have audible alerts when telemetry variables go outside reasonable bounds).
On my HW ESC, I didn't think there was any issue, but last weekend I had something strange happen. Here's the log:
About one minute into the flight I lost power. I didn't know what was going on so I just landed out in the field. I then noticed it was spooling back up and hit throttle cut. I flew the heli four more times, very carefully, and did not have any strange behavior. In the plot I show RPM, SC (throttle cut) and SH (throttle hold). You can see that I did not accidentally hit either of these switches. Also shown is PWM, which clearly shows I lost throttle signal, and which also shows it going back into slow start spoolup as I observed. Not sure if this is related to the telemetry issue I'm seeing with the Castle ESC's (collisions), but I thought I would bring it up because I cannot see any other reason for this to happen.