User manual

Operating Instructions data logger
7
EN
8. Alarm Function
8
.3. Acoustic Alarm
When an alarm is triggered when the acoustic function is active (see chapter
6
.2.4. Acoustic Function), an alarm tone sounds in addition to the alarm symbol
on the display. The logger stops emitting the tone when the measured value is
within the corridor.
8.4. Using the Alarm Hysteresis
If you use the alarm function with an alarm hysteresis, the alarm will be trig-
gered and recorded every time the alarm thresholds are exceeded.
If the corridor between the selected alarm thresholds is very narrow, the alarm
will be triggered more often.
If, for example, you have selected 24 °C as your upper alarm threshold for the
room temperature and 10 °C for your lower alarm threshold and the room tem-
perature fluctuates between 23.5 and 25 °C during the entire measuring period,
then this would lead to the alarm being triggered and recorded much more often
than would perhaps otherwise be the case during a normal measuring period.
In order to prevent this from happening, you can set an alarm hysteresis. By
doing so you are defining a value which has to be reached in the selected value
corridor, the so-called “good sector” to switch off the alarm.
The alarm hysteresis is set to 1 °C in the previous example. This means that the
alarm will be triggered when the measured value has exceeded 24 °C and then
switched off again when it reaches 23 °C.
HYSTERESIS
Alarm display without hysteresis
Alarm display with hysteresis
Logging mode
Logging mode
Upper alarm
threshold value
Set value
corridor –
“Good sector”
Lower alarm
threshold
value
Blinking
Static
Upper alarm
threshold value
Set value
corridor –
“Good sector”
Lower alarm
threshold
value
Blinking
Static
8
.1. Alarm Configuration
The data logger management can be used to configure an alarm for each indi-
v
idual measuring channel which has been selected for display or logging.
First you must define both an upper and a lower alarm threshold so as to set a
corridor within which the values are deemed to be good. The data logger trig-
gers the alarm as soon as the measured value is outside this corridor, i.e. one
of the thresholds has been exceeded.
Please note: The alarm function will only be displayed for the channel groups
of the three measuring channels which have been previously selected to be
displayed and only in the operating modes M2 and M3 !
Alarm incidents of further selected measuring channels in logging mode are
saved regardless whether they have been selected to be displayed or not. This
means that alarm incidents of measuring channels that have not been selected
f
or display but which have been selected for logging will be saved.
All selected alarm incidents are also recorded when the display has been deac-
tivated in operating mode M4.
8.2. Alarm Symbol on the Display
The alarm will only appear on the dis-
play for measuring values which have
been selected to be displayed and
which have been configured with an ac-
tive alarm function. When an alarm has
been triggered on one of these measur-
ing channels, an alarm symbol appears
next to the measuring value for this spe-
cific hannel. The symbol continues to
blink until the measured value returns
to the preset corridor.
The alarm symbol stops blinking as soon as the measured value is within the se-
lected thresholds. The alarm symbol remains on the display.
This is to show the user that an alarm has been triggered and that an alarm in-
cident has occurred. If the threshold values are exceeded again, then the alarm
symbol starts to blink again.
The alarm symbol disappears when the memory is read out.
A hysteresis can also be set which switches off the alarm when the measured
value is once again within the corridor.
Display example for an alarm incident of
the measuring channel displayed in the
first measurement line.
Alarm display
Upper alarm
threshold value
Set value
corridor –
“Good sector”
Lower alarm
threshold
value
Blinking
Static
Logging mode
Reading out the value memory