i would like to set it also on the camera-plate. but when i tilt it more than 60° down, the picloc runs crazy. so you can't look down by 90°.
With off-axis mounting, such as the Tilt and Roll on an AV200, the only travel limits as far as PL is concerned are those imposed by the external pots i.e. maybe 110°. As Picloc remains stationary it suffers no ill effects.
However, when it is ON-axis, as you wish to do, i.e. on the camera plate, the PL is limited to around 55° of tilt before the Roll axis starts becoming a second Pan axis. At this point PL gets confused, doesn't know what to do and ... "goes crazy".
I have addressed this on the big gasser heli by mounting the PL on a swivelling bracket that allows it to be set at up to -35°. As we do not need very much upward tilt (blades, booms, motors etc. are NOT photogenic) the PL will not be subjected to very much more negative tilt than that. Perhaps another 10° at most. So at -45° of total tilt the PL is still comfortable and keeps its hair on.
The big advantage is that the forward tilt now has a bonus of up to 35° of extra camera angle. So if your camera is angled at 90° down (vertical) PL is still only at 55°. However, as I do not personally like the Google Earth vertical view much I have left the PL set at -20° with forward tilt at 55°, giving around 75° of camera forward tilt. It is early days yet because I have only just started flight testing the 3X so these angles are subject to change.
However, as always there is a payoff. If the PL is not mounted level, Roll commands will result in some sympathetic panning. This is not altogether as ugly as it sounds as in practice the subject is actually kept more centre frame during the Roll.
... Picloc has to be in flat position on startup ...
I am not sure this is the case. In the above installation, with the PL mounted at a negative angle, I adjust the SVR1 value until the camera plate is brought more or less level and this new position is accepted by PL as the 'Home" position. Start position can still be set differently.
The following video is the first flight test yesterday of the 3X mounted on a Copterworks AF25B petrol powered heli with CW gimbal (apologies for the rather gloomy camera setting). The purpose was to determine whether or not Picloc with its basic bench settings would perform sufficiently well to merit further investment in time and effort. Happily, the 3X performs immeasurably better than the preceding TRv3/2X series.