So if I understand well there is a "sync" command in Indi to say the focuser is at a certain value.
I don't see a way to sync in OnStep firmware, is there one except the "zero"?
If I follow Blueshaw, an offset of max/2 would solve this issue.
Just for info, here my focuser set-up (than explains why I don't need the negative value or offset)
#define MinAxis4 0.0 // minimum allowed Axis4 position in millimeters, default = -25.0
#define MaxAxis4 38.0 // maximum allowed Axis4 position in millimeters, default = 25.0
and whith this set-up I have 38000 steps to travel these 38mm with 0 fully retracted. (48 step motor, and approx 20,8/1 gear)
When I start I set the focuser mechanically to zero (0), initialize the focuser to Zero and from then travel to approx half travel where my focus usually is and I'm done.