Figure 3-1 External Level Trigger - Microscan MS-3 User Manual

External Level
Usage: This mode is effective in an application where the speeds of the convey-
ing apparatus are variable and the time the reader spends scanning each
object is not predictable. It also allows the user to determine if a noread
has occurred.
1
Object
detector
Object
detector
Definition: External Level allows the read cycle to begin when a trigger (change of
state) from an external sensing device is received. The read cycle
endures until the object moves out of the sensor range and the active
trigger state changes again.
Serial Cmd: <K200,2>
Important: Level and Edge apply to the active state of the trigger that exists while
the object is in a read cycle. Negative is the electrical state (0 V/gnd) of the trigger sig-
nal associated with the appearance of an object. Positive is the electrical state of the
trigger signal received by the reader and associated with the subsequent disappearance
of the object.
Initiate Read Cycle:
Object # 1, moving in front of
the detector beam, causes a
change in the trigger state, initi-
ating the read cycle.
End Read Cycle:
The same object, moving
1
out of the detector beam,
causes another change in
the trigger state, ending
the read cycle.

Figure 3-1 External Level Trigger

Chapter 3 Read Cycle
Active
0
Active
0
MS-3 CCD Reader User's Manual
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