ADLINK PCI-8158 - Manual (Page 56)

46 Operation Theory
pulses per 1mm and the motor will move 1mm if the motion con-
troller send 1,000 pulses, It means that when we want to move 1
mm, we need to send 1,000 pulses to motor driver then we will get
the encoder feedback value of 10,000 pulses. If we want to use an
absolute command to move a motor to 10,000 pulses position and
current position read from encoder is 3500 pulses, how many
pulses will it send to motor driver? The answer is (10000 – 3500 ) /
(10,000 / 1,000)=650 pulses. The motion controller will calculate it
automatically if you have already set the “move ratio”. The “move
ratio” equals the feedback resolution/command resolution.
4.2.2 Absolute and relative position move
There are two kinds of commands to locate target positions in the
coordinate system: absolute and relative. Absolute command
means that for a given motion controller a position, the motion
controller will move a motor to that position from current position.
Relative command means that to move a motion controller dis-
tance, the motion controller will move motor by the distance from
current position. During the movement, you can specify the speed
profile, meaning you can define how fast and at what speed to
reach the position.