Xerox DocuColor 12/DCCS50, Service Manual

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10-37 DocuColor 12/DCCS50
Overview, Control Architecture
Principles of Operation
Reissue
Overview
This machine uses distributed computer technology and data communications to control its
operation. Overall machine control is provided by the Image Output Terminal (IOT) CPU
Printed Wiring Board Assembly (PWBA). However, additional intelligent PWBAs control sub-
system functions. These PWBAs talk with each other using serial communications paths.
There is no local network bus. Run-time monitoring and self-tests allow the control system to
detect faults.
This chapter will discuss the following subjects:
1. Control Architecture
2. Non-Volatile Memory
3. Machine Usage Modes
4. Self-test
5. Copier Timing
6. Job Control
7. Digital Front End
8. Foreign Interface
Control Architecture
As shown in Figure 1 , the center of the control architecture is the IOT CPU PWBA. This
assembly uses 2-wire and 4-wire serial communications links to pass command and status
messages with several other standard and optional assemblies.
• The Post-IPS (Image Processing System) PWBA
• The Pre-IPS PWBA via the Post-IPS PWBA
• The Duplex Automatic Document Feeder (DADF) via the Post-IPS PWBA and Pre-IPS
PWBA
• The User Interface (UI) Base PWBA
• The Portable Workstation (PWS)
• The Tray 6 (High Capacity Feeder - HCF)
• The Sorter/Mailbox/Offset Copy Tray (OCT)
• The Foreign Interface
• The Integrated Digital Front End (IDFE)
In addition, the address and data buses from the IOT CPU are connected to the following:
• The IOT Non-Volatile Memory (NVM) PWBA
• The IOT Drive PWBA
• The Halftone PWBA.
Three of these PWBAs deserve special mention. First, the IOT Drive PWBA contains the
decoders and drive circuitry which connect the IOT CPU with discrete line outputs and discrete
line inputs. These discrete lines are connected with motors, clutches, solenoids and sensors
throughout the machine.
Second, the IOT CPU PWBA provides all of the connections between the User Interface and
the rest of the machine. All status data from other PWBAs must be processed by the IOT CPU
PWBA, which then provides the appropriate messages to the UI Base PWBA. When some-
thing is entered at the UI, the UI Base PWBA typically sends messages to the IOT CPU PWBA.
As a result of these messages and its own processing, the IOT CPU PWBA sends commands
to the rest of the machine.
Third, the control and status communications path between the IOT CPU PWBA and the DADF
is routed via both the Post-IPS PWBA and Pre-IPS PWBA. The nature of the routing differs
between the two PWBAs. The signal path through the Post-IPS PWBA is direct, and no active
circuitry on that PWBA is involved. However, all messages between the IOT CPU PWBA and
DADF are handled by the control processor on the Pre-IPS PWBA. Therefore, the Pre-IPS
PWBA control processor shares control of the DADF with the IOT CPU.