Compuprint MDP40B Programmer Manual - Manual (Page 133)

B-26
In case the vertical scanning is performed normally:
between x , y and x , (y + w)
In case the vertical scanning is performed in inverse
direction:
between x , (y + w) and x , y
When the command is performed, the serial line sends the following message:
DC4 DC4 ESC ? n
Where n is a string of n bytes containing the decoded barcode.
If invalid parameters are encountered, or the scanning area goes outside the logical
page margins, n will have the value 0. If the reading was not successful, n = and the
string will be composed of 10 "?" characters.
x
y
w
y+w