ADLINK PCI-8154 - Manual (Page 63)

Operation Theory 53
to set a new command into 2nd buffer before executing register is
finished, the motion can run endlessly. The following diagram
shows this architecture of continuous motion.
Besides position command, the speed command should be set
correctly to perform a speed continuous profile. For the following
example, there are three motion command of this continuous
motion. The second one has high speed than the others. The
interconnection of speed between these three motion functions
should be set as the following diagram: