55
Subject to change without notice
the autorange function is to be used with care.
For measurements on high impedance source and
measurement voltages in the range (90%) of full
scale 1 V, changing to a higher range is possible
with activated Auto function. the Hm8112-3 has
an input impedance of 10MΩ in the 10 V range
instead of 1 GΩ in the 1 V range. By loading a high
impedance source of several 100 MΩ with by input
impedance of 10 MΩ the measurement result will
be errouneous.
10.6 menu structure / menu prompting
From every measurement function the menu can be entered by
pressing MENU
18
. Within the menu, every button which can be
used is illuminated. The menu can be always left by pressing
ESC
19
without acceptance of entered values.
call of the menu by menu
18
.
Choice of menu item with
20
and
23
. The menu item is
opened with MENU or branch to the next menu level. Selection
of parameters shown with and . Acceptance of parameters
changed with MENU . If the menu is left, the instrument will
return to the last measurement function.
19
esc
Leaving the menu. Return to the last measuring function without
acceptance of the value entered.
20
Rotating menu prompting. Jump to the next menu item with
every key operation. On reaching the last menu item the display
continues with the first menu item.
23
Rotating menu prompting. Jump to the previous menu item with
every key operation. On reaching the first menu item the display
will roll over and continue with the last menu item.
22
enter
Use this button only in the logger menu „6:Logger.“ Switching
to the next buffered value by every key operation or acceptance
of an input.
if the scanner card (Ho112) is activated, the indi-
vidual measuring points will select with a push on
the enter button.
10.7 menu structure and function
The menu will be accessed by pressing MENU
18
. It branches
to the submenues described below.
0:time
The time intervals between the measurements are adjustable
from 0.01 s to 60 s. That means, a reading is taken every 0.01 s
or only every 60 s.
The sampling rate can assume the following values:
10 ms
(only via interface)
50 ms
(only via interface)
100 ms
(default setting after switch-on)
500 ms
1 s
10 s
60 s
That means, for example, that every 500 ms a measurement is
taken and the value is updated in the display. After switch-on a
value of 100 ms will be preset. Removal of the line voltage will
not save a selected value.
If the measurement function is changed, the HM8112-3 assumes
the default sampling rate, unless a sampling rate between 10 s
and 60 s is chosen. Then changing the measuring function sets
the sampling rate automatically to 1 s.
example:
The sampling rate for V
DC
is set to 60 s. Then the func-
tion A
DC
is selected. The instrument will reduce the sampling
rate automatically to 1 s. The new sampling rate applies to all
functions. If a sampling rate greater than 1 s is needed, it has
to be selected after every change of function.
A sampling rate of 60 s means:
the Hm8112-3 integrates the input voltage and the
the reference voltage over a period of 60 s. After
expiry of this time the value calculated will be
displayed by 6½ digits.
1:Filter
Selection of the number of values taken for averaging. In case
of selection of a number greater than 1, the selected number
will be taken for averaging. By calculating a new averaged value,
the first measured value will be discarded and the mean value
will be computed.
OFF
(default setting after switch-on)
2
4
8
16
2:temp
In this menu item the dimension for the temperature measure-
ment is selected.
° C
Degrees Celsius
° F
Degrees Fahrenheit
The dimensions selected last will be saved even if the mains
will be turned off.
3: sensor
Here the temperature sensor used is selected.
After switch on of the HM8112-3 and selection of the menu item
“3:Sensor“, if a measurement function other than temperature
measurement was set, PT 100 as temperature sensor is selec-
ted by default. If the thermocouple is chosen the HM8112-3 is
in measurement function
δ
TH
15
.
Also the instrument will return to the measurement function
δ
PT
13
after selection of the PT-sensor. The sensor type selec-
ted last will be stored in the instrument even if the main voltage
is turned off.
– K–type: thermocouples NiCr-Ni (default setting after switch-
on)
– J–type: thermocouples Fe-CuNi
– PT1000: platinum resistance sensor with R
0
= 1000 Ω
– PT100: platinum resistance sensor with R
0
= 100 Ω (default
setting after switch-on)
comp
For measurements with thermocouples a reference with a known
temperature must be defined. This reference temperature is
provided to the HM8112-3. Therfore three methods are possible:
1st: comp ext/ice
An external temperature test point acts as a reference, e.g. an
ice bath or another reference thermocouple with a temperature
c o n t r o l e l e m e n t s a n d d i s p l a y
c o n t r o l e l e m e n t s a n d d i s p l a y
