My setup is with a Spektrum DX20 and the Powerbox Mercury. The plane is a Mustang with air operated retracts and servo operated doors. Initially I set up the gear/door sequencer using the DX20 built in sequencer. It all was working correctly. The main and tail doors would open. Then the gear would come down and then the main doors would close. On gear up the main doors would open again, the gear would go up and all doors would close.
The problem is when I turn on the system after putting the plane together with the gear up and the doors closed. If the transmitter gear switch in the up position momentarily the tail gear will go down and tail door will open then the door quickly closes before the gear can go up breaking the door hinges. If I turn it on with the gear switch in the down position the main gear will go down while the main door is closed.
It was bound with the gear down so that if the transmitter gear switch is in the down position then it all stays in place when the receiver and transmitter is turned on. If I bound it with the gear switch up the sequencer would not jam when I turn on for the first time. However if the gear was down and sitting on its wheels the gear would momentarily collapse when I turned on. There is no easy fix.
I changed over to the built in Mercury sequencer and now it works perfectly. If I turn on with the transmitter gear down or in the up position it initially sets the gear in the up position (which is always safe) and the doors remain closed. I then have to cycle the gear switch for it to operate. I want to thank you for your excellent and thoughtful programming so that the gear sequence is always correct with no surprises. I am impressed.