I’m having a similar problem with my triicopter that has older plush escs that want a pwm value of about 1000 to arm using APM 2.5.
First setup was with kk2 and spectrum no problem arming.
Second setup was with APM and x9303 with piggybacked Dragon Link and I had to trick the PWM value lower by using the manual throttle trim tab. 996-1000
Trying to switch to dx9 with Dragon Link but I can’t get the values shown on MP to drop after trying calibration, programming the dx9 travel, sub trim, trim tab–but no luck even when the dx9 monitor show a below regular range, mp still sees it as 1100 or so (not low enough to arm the old plush escs).
Is there another way to lower the dx9 values?
Thanks for any assistance.
Although not the same model of ESC and motors, I had a problem with the E300 set also from DJI that sounds about the same as yours.
The ESC’s are opto-coupled and have a control range of 1120 to 1920us. So you should try to set your throttle channel to send between 1120 at minimum and 1920 at maximum. You can use the RC screen at MP to check these values (which are adjusted on the Servo Setup - Travel on the DX9) then perform a RC calibration as usual on the MP software.
If you want to use Throttle failsafe you must bind the receiver in a special way to achieve that (if the receiver has that capability).
What I did, was: Change the Travel limit low on the DX9 throttle channel to output about 1000us. With the bind plug on the receiver, power the receiver. Then remove the bind plug and use the bind menu on the DX9 to bind the DX9 to the receiver. When bind is complete (the DX9 says that) power everything off. Restore the Travel limit low on the DX9 to the value that will get you the 1120us. Set the Throttle failsafe value on MP to a value lower than 1120 and higher of 1000. So, if you lose radio contact the Throttle channel goes to 1000us and the Flight Controller changes to Throttle Failsafe active.
hope it helps
[quote=“Trams5”]Problem: Motors will NOT arm…The Initial Set-up appears to be working?
Hardware: DJI F550 with Opto 30A ESC’s, and DJI 2212/920 KV motors, added a 3 A UBEC, UBlox, Spektrum DX9 Tx and AR9020 Rx
Version APM: 2.6 running V3.1.3 firmware
Flight issues: Unable to Arm and start motors.
Message: M1 PreArm: Check FS_THR_Value
Rx inputs are seen, but out puts are not showing on APM Planner screen; I see flashing, but not red flashes for Armed on APM. I have tried changing the settings on Fail Safe (FS):
10 pwm higher than Ch 3 when off…(off is 1098)…1108
10 pwm lower than Ch 3 when on…(on is 1111)…1101
above 910; introduced 1105…did not work/Arm??
Please give me your thoughts on what needs to be tried to solve this issue and get the motors moving )