Scan Sense Timing Timing Diagram; Scan Sense - Metrologic S4800 microQuest Series Installation Manual

S S T
CAN ENSE
Timing Diagram
The Timing Diagram (see Figure below) illustrates the correct power up
procedure to ensure that the laser diode is not damaged upon start up of the unit.
Upon start up, both scan Enable and Laser Enable are to be held high. In this
state, both the scan mirror and the laser diode are not functional.
A minimum of 2ms after the unit has obtained the proper working voltage;
Scan Enable can be driven low to turn on the scan mirror. A minimum of 50 ms
must elapse after enabling the scan before driving the Laser Enable low to turn
on the laser diode.
Caution: The laser is susceptible to permanent damage if enabled less than 50
ms after the Scan Enable has been activated. This requirement must
be strictly adhered to or the limited warranty on page 23 is void.
The unit is now ready to scan bar code data.

Scan Sense

The scan sense signal is a 50% duty cycle square wave with the transitions from
High to Low indicating a change in the scan direction, (see Figure 10). Valid
scan data occurs between these transitions.
If scan enable is High (off) the scan sense signal will stay High. If for some
reason the scan mirror is stopped (damage for example) when Scan enable is
Low (on) then Scan Sense will remain High.
16
IMING
Figure 11. Timing Diagram