THEORY OF OPERATION
4-9
Versapulse Select Service Manual
0621-499-01 01/94
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4.4 CONTROL ELECTRONICS
4.4.1 Overview
The control electronics executes stored software instructions to safely operate the system in response to user
inputs. For the purposes of this discussion the control electronics is divided into two major functional ele-
ments: the main processor (Mµp) and the safety processor (Sµp). Each processor runs its own set of software
instructions. The instructions are different, but are written to run in conjunction with the other, i.e., each relies
on actions by the other in order to operate. If either fails the other will be inhibited from continuing. The two
processors communicate using a shared memory integrated circuit. Each reads and/or writes to specific areas
of this shared memory to communicate with the other.
The main processor system provides overall control of system operation. It includes the following circuits/
functions.
Main Processor (Mµp) - Runs the main software program to provide overall control of system
operation. Includes a 68000 microprocessor and its supporting circuits - ROM, RAM, programmable
timer, digital I/O, interrupt handling, clock, and µp bus support circuits. Described in subtopic 4.4.2.
Shutter/Footswitch /Remote Interlock Circuit - Operates and monitors the position of the shutter;
detects footswitch position; and monitors the remote Interlock connection. Described in subtopic
4.4.3.
Servo Motor Circuit - Positions the servo motor to point the servo imaging mirror to the selected
Ho:YAG head. Described in subtopic 4.4.4.
HVPS & PFN Control Circuits - Provides charge level, lamp select, charge command, and triggering
inputs to the HVPS and PFN circuits. Monitors status line inputs from the HVPS. Described in
subtopic 4.4.5.
Energy Monitor Circuits - Provides three channels of Ho:YAG pulse energy monitoring. Described
in subtopic 4.4.6.
Touch Screen and Remote Control Circuits - Provides user display and input functions. Described
in subtopic 4.4.7
Aiming Diode Laser Circuit - Sets the aiming diode laser to its off, low, medium, or high intensity.
Described in subtopic 4.4.8.
Fiber and Blast Shield Position Sense Circuits - Monitors the position of the fiber and blast shield.
Described in subtopic 4.4.9.
Service Attenuator/Switch Monitor Circuits - Operates and monitors the position of the service
attenuator. Monitors the condition of the service and diagnostic push-buttons located on the CPU
PCB. Described in subtopic 4.4.10.
Coolant Temperature and Conductivity Monitoring Circuits - Monitors the coolant temperature
and conductivity. Described in subtopic 4.4.11.
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