Advanced Measurement Technology 273A, Руководство пользователя

Страница: 31 / 70

25
5. OPERATING INSTRUCTIONS
5.1. Introduction
Although the Model 273A is a complex, microprocessorcontrolled analytical instrument, its
operation is, nevertheless, straightforward. The instrument's front panel has been carefully
designed with attention to humanengineering considerations. Its two-line alphanumeric display
continuously displays the potential and current on one line, while guiding the operator through
the operating sequence via messages displayed on the second. A special Scan Status Display is
provided that continuously indicates the stage in progress of an ongoing scan. Front-panel
indicator lights allow the user to ascertain the setup at a glance.
A battery-powered parameter backup system retains all selections and parameter values. When
the 273A is powered up, all selections and parameter values are as they were at the end of the
previous operating session. The default values can, however, be restored by reinitializing the
system via FUNCTION 10. The use of FUNCTION 10 is described in Section 5.2.4.
Another way to restore the default values is by pressing the LOCAL key when powering up. The
key must be held in until the message "SYSTEM REINITIALIZED" appears on the front-panel
display.
No effort has been spared to make the Model 273A an easy instrument to operate. Nevertheless,
information beyond that provided on the front panel is required for optimum performance in
many situations. This chapter of the manual addresses those needs.
Instructions for operating the unit remotely via either the RS-232C or GPIB (IEEE-488) interface
port are given in the separately bound Model 273A Remote-Programming Command Handbook.
5.2. Front Panel
The Model 273A's front panel (Figure 5-1) is divided into clearly delineated functional areas. The
SCAN STATUS DISPLAY, OVERLOAD INDICATORS, and ALPHANUMERIC DISPLAYS are
located at the top of the panel. The key/indicator areas, SCAN SETUP, CONTROL, MODE,
CELL, INPUT, FILTER, IR COMPENSATION, CURRENT RANGE, OUTPUT, and INTERFACE
are located beneath them. Each area's features are discussed in some detail in the following
paragraphs.
5.2.1. Alphanumeric Display
The Model 273A incorporates an LCD alphanumeric display able to show two lines (40
characters each) of both upper- and lower-case characters. The measured potential and current
are continuously displayed on the upper line. Messages and parameter values appropriate to the
operation being performed are displayed on the lower line.
For example, when a setup parameter key is pressed, the previously set value is displayed,
together with the message, ENTER XXX (XXX signifies the parameter). The new value can then
be keyed and ENTER pressed, after which the new value will be displayed. Pressing ENTER
again clears the new value from the display so that it can return to the normal bottom line mode,
in which the bottom display line can scroll through several possible display options, advancing
once each time the ENTER key is pressed. The choices are:
1. Second Display Line Blank.
2. Charge in coulombs.
3. Log of I if LOG is enabled.