ASCOM LACERTA MOTORFOCUS, User Manual

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LACERTA MOTORFOCUS 17 2016
Main menu
Push
Esc and Ent at the same time to reach the Main menu, Use In/out to select an
entry and press Ent to enter it. Here you can find the following settings:
Focuser menu:
Backlash:
The value of basic backlash compensation (the value can be between 0 and
255). Backlash compensation takes place only when the rotational direction of
the motor is changing (in/out).The movement of motor increases by this value,
without counting the backlash steps, when the direction of motor rotation is
changing. The idea is to correlate the counter with the focuser position, not the
motor position.
The process when the direction of motor revolution is changing:
Backlash (position uncounted) + Steps (position counted)
If this function is activated (the value is not 0) the ’B’ character will appear at
the upper row of the display.
Of course it is necessary to determine the backlash of your system first. You
can measure the correct value of backlash using the following simple method
indoors, or use a star instead:
Mount a Dial indicator to your focuser, then move focuser to any position (e.g.
Pos: 1000 ). Reset dial indicator and Backlash value. Activate single stepping
mode, than move focuser further in the same direction (e.g Pos: 1050 ). After
that move back the focuser, until the dial indicator reaches 0 again. Read the
position on the display (e.g
Pos: 975 ). Because the motor needs 25 more
steps to reach the absolute position, write 25 to Backlash value and repeat the
process to recheck.
Tip!
This process is also suitable to define the resolution of our system (mm/step).
Do this calibration method at focus position, because the backlash is not equal
in every focuser position due to deviations of gear teeth profiles and motor
stepping angles (approx. +/- 5% at full step).
BacklChg:
The Backlash change is the step limit of switching between two backlash
copensation modes (the value is from 0 to 50). The „ Basic ” backlash
compensation is accurate in case of small motor movements at specified
position (functionally around the right focus position), but it’s not working with
enough accuracy in case of large movements. That’s why the method in case
of large movements is approaching the desired position from
one direction
only (in or out) to eliminate any backlash. To move 15 steps out it would move
e.g. 100 steps out and 85 in, to reach the position. This is very precise. Below