Impresicion using movec

Hello everyone,
I am working on a cobot UR5 and I send it URscripts via Ethernet connection. I send it a very small program that consists of :

  • move to a point (movec or movel)
  • stopl(2)
  • sleep(1)
    The end point has a relative error of a couple millimeters that changes slightly with the speed given to the move order. It only happens with the movec, not with the movel. I tried to change the intermediate point of the movec, I tried to remove the stopl and the sleep, but still I get the same imprecision. Is that simply inherent to the movec function ?
    I can give further information if needed, I just wanted to know if it is supposed to happen in the first place.