Comtech EF Data CDM-500 - Manual (Page 22)

Rev. 1.3 4–1
4
Chapter 4.
PHYSICAL DESCRIPTION
The CDM-500 is constructed as a 1U high rack-mounting chassis, which can be
free-standing, if desired. It is provided with rack-handles at the front to facilitate
its removal from, and placement into a rack. Figure 1 shows the front and rear
panels of the modem.
4.1 Front Panel
On the front panel of the unit is the Vacuum Fluorescent Display (VFD), keypad, and
eight LED indicators. The user enters data via the keypad, and messages are displayed on
the VFD. The LEDs indicate, in a summary fashion, the status of the unit.
The Vacuum Fluorescent Display (VFD) is an active display showing 2 lines, each of 24
characters. It produces a pleasing blue light, the brightness of which can be controlled by
the user. It has greatly superior viewing characteristics compared to a Liquid Crystal
Display (LCD), and does not suffer problems of viewing angle or contrast.
The keypad comprises six individual keyswitches, mounted directly behind a fully sealed
membrane overlay. They have a positive ‘click’ action, which provides the user with
tactile feedback. These six switches are identified as UP ARROW, DOWN ARROW,
RIGHT ARROW, LEFT ARROW, ENTER and CLEAR. The functions of these keys are
described in the ‘Front Panel Operation’ section.
There are 8 LED indicators. The functions of these indicators are shown in the Table 1
below: