The Print Engine; B Serial Communication; The Communication Channels - QMS -ps 800+ User Manual

A.2 The Print Engine
Once in the print engine, the video data is used to modu-
late a tightly focused beam of light produced by a semi-
conductor laser. This laser beam is directed to a rotating,
hexagonal mirror which causes the beam to scan across
a photosensitive print drum. Each scan results in a raster
line on the print drum. The raster lines are transferred
from the print drum to the paper by electrostatic attrac-
tion and heated-roller fusion. The result is a high-quality,
smudge-proof image on standard copier paper.
B Serial Communication
Serial communication is asynchronous, start-stop, with 8
data bits per character (of which the eighth bit mayor
may not be used for parity), one start bit, and two stop
bits.
B.1 The Communication Channels
The QMS-PS 800+ is equipped with two bidirectional
communication ports:
1. 25-pin RS-232 serial I/O connector.
2. 9-pin RS-422 serial I/O connector (AppleTalk com-
patible).
These channels are selected with the mode switch on the
printer. The procedure to do this is explained in Part II
"Tutorial", Section E.4.
Advanced User's Information
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