Dell MH941 - Manual (Page 25)

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Appendix B
MH941 Scan Head Pin Assignments
Pin Signal Name Function
1 Flip Sense A square wave output signal that changes polarity
when the scan mirror drive circuit changes the
motor direction. The frequency is approximately
19 Hz to achieve a nominal 38 flips/scan per
second.
Note: The polarity and mirror direction do not
necessarily change at the same time.
This is an open collector output capable of sinking
25 mA via an external pull up resistor connected
to a voltage not to exceed +20 VDC.
2 Data An output digital representation of the scanned bar
code. A low level represents a bar and a high level
represents a space.
This is an open collector output capable of
sinking 25 mA via an external pull up resistor
connected to a voltage not to exceed +20 VDC.
3 Decode LED The scan head is equipped with LED and beeper
assemblies. A +5 VDC to 12 VDC input to the
head at this pin will light the green LED and if
oscillated at about 2 KHz, drive a beeper.
This should be supplied with no more than 30mA
of current.
Typically, this is used to indicate a decode has
occurred.