Printronix L5535, Maintenance Manual

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II–160
Chapter 8
Operational Sequences
Electronics Initialization
EPRDY Signal
This signal is asserted by the print engine to inform the controller that the
engine is ready for communication. When this signal goes true, the controller
may poll the engine status by sending the “Basic Read Status” command.
SYNC Signal
When power is turned on, the engine asserts the SYNC signal (raster sync) at
fixed intervals (937.5 µsec for 240 dpi, 750 µsec for 300 dpi, or 562.5 µsec for
400 dpi) in order to indicate the horizontal scanning start time for printing.
Program Load
While the engine is initializing the MC board (see below), the controller loads
the software from the flash memory.
MC Initialization
The engine performs a memory check/initialization and a timer initialization.
Wait For Controller
After performing the MC initialization, the engine will wait for the controller
board to finish loading the software and begin its initialization. At this point,
the engine will be in a fault state because the CPRDY signal from the
controller will not yet be asserted. As a result, the RDY signal from the engine
will not be asserted.
RESET Engine
After the software loads and begins its initialization, it will assert the CPRDY
signal, and then send a RESET command to the engine. This causes it to
clear the error caused by the CPRDY signal being de-asserted (above), and
begin mechanical initialization.
RDY Signal Assertion
If no errors are found while the mechanical initialization is being performed,
the engine will assert the RDY signal and will be ready to begin printing.
Software/Controller Initialization
While the engine is performing mechanical initialization, the software will read
in the fonts, configuration, etc. In addition, it will periodically (once per
second) send the “Read Status” command to the engine to read back any
errors within the engine.
Switch To Online
If no errors are reported while reading the fonts, the printer will go online. If
any errors are reported by the engine, the error message will be displayed on
the control panel and the printer will go into a fault state.