Comtech EF Data DT-4500-A Series - Manual (Page 71)

DT-4500-A Series Downconverters Revision 1
Front Panel Operation MN-DT4500A
5–3
5.1.3 Keypad
The keypad comprises six individual keyswitches. They have a
positive ‘click’ action, which provides tactile feedback. The
function of the front panel keypad is as follows:
Use the ENTER key to select a displayed function or to execute a modem configuration change
Use the CLEAR key to back out of a selection or to cancel a configuration change that has not been
executed since ENTER was last pressed. Pressing CLEAR generally returns the display to the
previous selection.
(Up, Down)
Use the ▲ ▼ arrow keys to move to the next selection or to move the cursor position. Most of
the menus (space permitting) include arrow key hints to guide operation.
(Left, Right)
Use the ◄ ► arrow keys primarily to change configuration data (numbers) at the current cursor
position. They may be used occasionally to scroll through a number of choices at the current cursor
position. Most of the menus (space permitting) include arrow key hints to guide operation.
The keypad has an auto-repeat feature. Holding a key down for more than 1
second repeats the key action automatically at the rate of 15 keystrokes per
second. This is particularly useful when editing numeric fields with many digits,
such as frequency or data rate.
5.1.4 Vacuum Fluorescent Display (VFD)
The DT-4500-A features a Vacuum Fluorescent
Display (VFD). The VFD is an active display showing
two lines of 24 characters each. It produces a blue
light, the brightness of which can be user-adjusted. Compared to a Liquid Crystal Display (LCD),
it has greatly superior viewing characteristics and does not suffer problems of viewing angle or
contrast.
On most menu screens, you will observe a flashing solid block cursor, which blinks at a once-
per-second rate. This indicates the currently selected item, digit, or field. Where this solid block
cursor would obscure the item being edited (e.g., a numeric field) the cursor will automatically
change to an underline cursor.
If you were to leave the same screen displayed for weeks at a time, the VFD could become
‘burnt’ with this image. To prevent this, the unit has a ‘screen saver’ feature that activates after
1 hour. The top line of the display will display the circuit ID, and the bottom line will display
‘Press any key...’ The message moves from right to left across the screen, then wraps
around. Pressing any key will restore the previous screen.