Omron V440-F User Manual page 289

Appendices
External Level
Usage:
Definition:
Serial Cmd:
Important: Level and Edge apply to the active logic state (Active Open or Active Closed) 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
Usage:
Definition:
Serial Cmd:
F-6
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.
This mode is effective in an application where the speeds of the conveying apparatus
are variable and the time the reader 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.
<K200,2>
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.
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 End of Read Cycle setting, a
timeout or new trigger occurs.
<K200,3>
V440-F C-Mount Code Reader User Manual