EPD/HB/40521/000
ISSUE 5
EPD TECHNICAL HANDBOOK Page 16
Figure 3.2 - LCD Display Segments
3.2 Audible And Visible Alarms
3.2.1 Alarm features
Overview
The EPD contains a sounder and alarm LED (see
Figure 3.1), which are activated together when
certain alarm conditions occur. Alarms are also
indicated in various ways on the LCD. Under
alarm conditions the LED illuminates red and the
sounder sounds at 4 kHz or 2 kHz with an intensity
of between 98 to 101 dBA (4 kHz Loud) at 20 cm.
It is possible to disable the sounder and/or LED so that only one or neither will
activate, but alarm flags on the LCD remain until the condition is normalised. The
alarm sounder can be configured for quieter operation, for example, for office or
hospital environments.
Alarms are acknowledged by pressing the button (long press). This action will
extinguish the alarm LED and mute the sounder. It is possible to disable the mute
function, via the EPD IR communications link (see section 3.2.5).
Note that certain operations and events will automatically mute the audible alarm for
a short period, because of the high electrical current required. These are as follows.
The period of interruption to the sound output is also given:
Operation or event. Typical mute period.
Communication over the IrDA link 1 second or more, depending upon the
application.
Communications over the
teledosimetry link.
Less than a second.
Backlight activated (from the button). Default display timeout ( typically 10
seconds ), during which the backlight is on.
Battery test ( typically every 15
minutes ).
Less than 1 second.
Figure 3.1 - Alarm LED
And Sounder
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