ODC001 Servo Motor Driver
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Fig. D.2 Stage limit switches
D.2.4
Minimum and Maximum Positions
These positions are dependent upon the stage or actuator to which the motors are
fitted, and are defined as the minimum and maximum useful positions of the stage
relative to the ‘Home’ position - see Fig. D.3.
The distance from the Minimum position to the Maximum position is the ‘useful travel’
of the stage. It is often the case that the Minimum position is zero. The Home and
Minimum positions then coincide, with movement always occurring on the positive
side of the Home position.
Rotary stages have effectively no limits of travel. The Minimum and Maximum
positions are conventionally set to 0 and 360 degrees respectively. When the position
of a rotary stage is requested, the answer will be reported as a number between 0 and
360 degrees, measured in the positive direction from the Home position.
Fig. D.3 Minimum and Maximum Positions
Rotary stage
Linear stage
Datum switch
-ve limit switch
+ve limit switch
(or stop)
Trave l
Min. position (zero)
(home)
Max. position
Offse t
-ve limit switch
SW positive limit
SW negative limit
