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78 Operation Theory
4.6.3 General Comparator
The general comparator let users to choose the source to com-
pare. It could be chosen from command, feedback position coun-
ter, error counter or general counter. The compare methods could
be chosen by equal, greater than or less than with directional or
directionless. Also the action when condition is met can be chosen
from generating interrupt, stop motion or others.
4.6.4 Trigger Comparator
The trigger comparator is much like general comparator. It has an
additional function, generating a trigger pulse when condition is
met. Once the condition is met, the CMP pin on the connector will
output a pulse for specific purpose like triggering a camera to
catch picture. Not all of axes have this function. It depends on the
existence of CMP pin of the axis. The following diagram shows the
application of triggering.
In this application, the table is controlled by the motion command,
and the CCD Camera is controlled by CMP pin. When the compar-
ing position is reached, the pulse will be outputted and the image
is captured. This is an on-the-fly image capture. If users want to
get more images during the motion path, try to set a new compar-
t
v
1 2 3 4 5 6
CCD
Camera
t
v
1 2 3 4 5 6
CCD
Camera
Trigger Output