I guess I wasn't as clear as I had hoped about my question. To be more specific: When the commanded value for a move is converted into steps (or microsteps) and that number of steps contains a fraction....What happens to the fractional part of a step????
I am not speaking of dropped steps as would be the case in a stepper whose movement is inhibited by not being able to complete a step due to load, velocity, acceleration, setup or duration. I am only questioning whether LinuxCNC drops the non integer portion of a step when converting from commanded position change to steps. I have assumed that the system can only issue steps as an integer and that the fraction is dropped. If this is the case then the system can ONLY "round down" so all commanded moves that don't convert to integers wind up being short of the desired move. Never "long". The only way the error can "even out" is by virtue of having the effect balanced by equally "short" moves in the opposite direction. As I have designed my program there are many more moves in one direction than in the other so I assume that the "shortness" accumulates over a large number of moves. My calculations for the accumulation of error in my system seem to match the measured results. I can change my program to try to balance the forward and back moves or I can add a stage of reduction to the A axis to reduce the magnitude of the "leftovers" or both but before I proceed I would like to be sure that the trajectory planner does as I assumed "Only round down". Cecil ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
