I am using CubeOrange and RFD900x modems with RC passthrough functions. Uplink control via RC and GCS commands are okay and the UAV responses without latency. But HUD display was delayed about 1.8 seconds. To improve this trouble, some key changes were made as followings:
Modem RTS/CTS hardware wiring: RTS to CTS, CTS to RTS
Airside Modem Setting:
BAUD=115, AirSpeed=125, Duty Cycle=100,
ECC=off, RTSCTS=On, MAVlink=On, Max Window=60 or 40
GPO1_1 SBUSOUT=SBUS1
Ground-side Modem Setting:
Same as the Airside except RTSCTS=Off, GPO1_1 SBUSIN=On
COM Port Setting: Baud rate=115200
The HUD display works without delay as like as connection via USB.
But parameter loading is too slow and looks like ‘never ending’ after showing ‘Getting Params’ message window. Nevertheless, the HUD display and Quick Data display responded in real time without any delay. Increasing SR1_PARAMS does not solve parameter loading problem.
Parameter loading via USB is still same and fast, and read within a few seconds as always.
Please advise how to improve very slow parameter loading. Thanks
I also set BRD_SER1_RTSCTS,0 to ensure the Auto detection of RTS/CTS doesnt interfere.
I also set the modem Tx Power to 27 - a bit lower power for relatively short range work - seems OK for a few kilometers, and I can safely run the modem from the serial port +5v power
and I meant to say: SERIAL1_PROTOCOL,2
which it probably already is, but just checking.
I already tried several cases including your kindly advice. Max Window time does not improve even though it is somewhat related with data bandwidth.
Definitely, RTSCTS flow control makes delay of the HUD display BEFORE RTSCTS hardware wiring change as well as parameter switching, and long (never ending) delay of parameter loading AFTER RTSCTS configuration changes although the HUD problem was fixed. These two situations are conflicting each other at this time.
When the change was back to previous RTSCTS wiring and flow control, the slowest parameter loading problem are disappeared while the HUD display delay comes back again.
I guess that these situation may be caused by certain reasons, for example mis-matching of Mission Planner and modems or unexpected bugs in the Mission Planner.
I’ve had plenty of sets of RFD900X’s and UX’s and TXMODs working with my settings.
Including with the SBUS in and out for RC control.
Here’s the settings I’ve got on a couple of old (original) 3DR 433MHz radios that I have here for tests and fun
Basically the same except I only have Air Speed 128 because they wouldnt do 200.
It takes them about 8 seconds to download params from a Cube Orange.
HUD is reasonably responsive, with some very small amount of lag and jerkiness, but is very usable.
I’ve even enabled RTS/CTS and put back BRD_SER1_RTSCTS,2 or 1 and they are still OK, but they do spend about 20 seconds attempting parameter download from cold boot (the Timeout counts down to about 8) and then they are OK after that - probably allowable for radios that are probably 10 years old or so.
I disabled all the RTS/CTS and the param download is back to normal (more like a USB connection)
I know this is not an RFD900X, but still all the same settings I use with them
Do not use RTS/CTS with RFD modems when Mavlink Support is switched on in the config. This option adds a mavlink packet-based data throttle control; using it alongside CTS/RTS will cause issues.
