Citizen GSX-190 Service Manual download pdf (Page 30)

PN 4237242C

2.1-2

INSTRUMENT DESCRIPTION

SYSTEM OVERVIEW

The MD II cycle begins with the presentation of a whole-blood sample to a self-washing

aspirate probe. The MD II then aspirates 12 µL of blood, dilutes and analyzes the sample and

makes the results available to a Liquid Crystal Display (LCD) and Printer. Instrument

intelligence is provided by a program loaded at power ON from a diskette. Interaction with

the instrument is largely through use of a menu system displayed on the 4-row by 40-column

LCD and a numeric keypad, with select functions provided through dedicated keys.

Software Menu System

Figure 2.1-2 shows the software menu tree. This is the same menu tree that is shown and

described in the customer documentation except that the three hidden menu items for service

personnel are added. These hidden items, shown in bold on the diagram, are not shown on

the instrument’s display nor in the customer’s documentation. Quick steps to access these

hidden items are in Heading 4.2, ACCESSING THE HIDDEN SERVICE MENU ITEMS.

Software Tables

Instrument cycling is accomplished using diluter tables. A diluter table is a collection of

software functions. The software function performs the action requested by the table, by

enabling the appropriate electrical drivers. The table determines specifics, such as when to

perform a certain action, and for how long. For instance, to drain a bath, a solenoid valve

must be opened to open a fluid path to waste. The diluter table specifies when this valve

opens and for how long. On the MD II, a peristaltic pump is used to move waste fluids. The

function to turn the pump stepper motor on is given the step rate and the total number of

steps. The diluter table also specifies some functions that are electronic in nature. Taking a

Hgb reading and accumulating aperture data are two such functions.

This table method allows for simple changes in the diluter cycles. Since the main software

does not need to be changed, only specific numbers in a specific diluter table change. All the

other tables are unchanged, which would not be true if a change was made to the software

function.

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Citizen GSX-190 Service Manual Page 30