Hi,
I Have an S900, can not get the motors to start. Everything appears normal, compass calibration completed successfully. It is linked to the controller, however it just sits there when I try to start the motors. What I am missing?

Also in the A2 flight control system software under the tools bar in the topographic view, when the mouse is moved over the devices the outline the all are highlighted except the PMU. is that an issue?

Check all your wiring .  If your PMU is not showing its because dji assistant is not detecting it.  Make sure power Cable is connected properly, you should see a light come on the PMU when you turn on the craft.  Also check the other connections.

The PMU has the green light on, but when you pass the mouse over the other units they are highlighted and you can click on them and they display the device unit the PMU is outlines but you cannot click on it. I was wondering if that was a problem. it also does not show up in the plain list

I think I may know my problem. I am using the Futaba 14sg transmitter. the only way I can get it to talk to the S900 is the fasst 7ch mode. I can set up the servo but in the control mode switch section I can switch between the three modes, but when I turn the transmitter off it does not go to the failsafe position and I believe that is because in the 7 ch FAsst mode only channel 3 has a failsafe setting. Ideas?

Change the controller to FASST-Multi mode and recalibrated and now motors respond.