User`s manual

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MS-3000 Single Head Decoder User’s Manual
2-15
2–Menu Config.
External Edge As with Level, Edge allows a read cycle to be
initiated by a trigger signal from an object detector
when it detects the appearance of an object (rising
edge). But unlike Level mode, the removal of an
object (falling edge) does not end the read cycle.
With Edge enabled, the read cycle ends with a good
read, a timeout, or a new trigger (figure -1).
Serial Data The decoder accepts an ASCII character from the
host or controlling device as a trigger to start a read
cycle.
Serial Data &
External Edge
The decoder accepts either an external trigger or a
serial ASCII command to start a read cycle.
a. Continuous Read 1 Output will allow an output regardless of how Good Decode Read is set.
b. Level and Edge apply to the active logic state (positive or negative) that exists while the object is
in a read cycle, between the rising edge and falling edge. For the purpose of this discussion, ris-
ing edge is the trigger signal associated with the appearance of an object and falling edge is the
trigger signal associated with the subsequent disappearance of the object.
Selecting: Has this effect:
Second trigger
The same object,
moving out of the
detector's beam,
causes a second
trigger (falling edge
trigger) signal to be
sent to the decoder,
ending the read cycle.
1
First trigger
An object, moving in
front of the detector
beam, causes the
first trigger (rising
edge trigger) signal
to be sent to the
decoder, initiating
the read cycle.
Object
detector
1
Object
detector
Subsequent rising edge trigger
Object #2, moving in front of
the detector's beam, causes
a second trigger (rising edge
trigger) signal to be sent to
the decoder.
This signal initiates a new
read cycle
and
ends the
previous read cycle
provided
that New Trigger or Timeout
and New Trigger is enabled
and a good read or timeout
has not already occurred.
2
First rising edge trigger
Object #1, moving in
front of the detector
beam, causes the first
trigger (rising edge
trigger) signal to be sent
to the decoder, initiating
the read cycle.
1
Object
detector
Object
detector
Figure 2-1 External Edge Trigger Signals
Figure 2-1 External Level Trigger Signals