Microscan N2210WZ Owner's Manual page 111

External Level
This mode is effective in an application where the speeds of the conveying apparatus are
variable and the time the scanner spends reading each object is not predictable. It also
allows the user to determine if a No Read has occurred.
External Level allows the read cycle (active state) to begin when a trigger (change of
state) from an external sensing device is received. The read cycle persists until the object
moves out of the sensor range and the active trigger state changes again.
Important: Level and Edge apply to the active logic state (Negative or Positive) that
exists while the object is in a read cycle, between the rising edge and the falling edge.
Rising edge is the trigger signal associated with the appearance of an object. Falling edge
is the trigger signal associated with the subsequent disappearance of the object. This
applies both to External Level and External Edge.
External Edge
This mode is highly recommended in any application where conveying speed is constant,
or if spacing, object size, or read cycle timeouts are consistent.
External Edge, as with Level, allows the read cycle (active state) to begin when a trigger
(change of state) from an external sensing device is received. However, the passing of an
object out of sensor range does not end the read cycle. The read cycle ends with a good
read output, or, depending on the
trigger occurs.
QX-870 Industrial Raster Scanner User's Manual
Initiate Read Cycle:
Object #1, moving in front of the
detector beam, causes a
change in the trigger state,
which initiates the read cycle.
End Read Cycle:
The same object, moving out of
the detector beam, causes
another change in the trigger
state, which ends the read cycle.
Initiate Read Cycle:
Object # 1, moving in front of the
detector beam, causes a change in
the trigger state, which initiates the
read cycle.
Initiate Second Read Cycle:
Object # 2, moving in front of the
detector beam, causes another
change in the trigger state. This sig-
nal initiates a new read cycle and
ends the previous read cycle unless
Timeout is enabled and a good read
or timeout has not occured.
End of Read Cycle Mode
Scanner Parameters
setting, a timeout or new
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