Measured value correction and compensation
11.2.2 Zero-point adjustment
Many types of sensor need to be adjusted at least once or at regular intervals to
compensate for various instabilities. This can be done with the above-men-
tioned ´Set measured value to zero´ - but also with the special
zero-point ad-
justment
which does not influence scaling. If this function is used, the zero-
point error is not stored as base value but as
zero-point correction
; (see
12.3.7).
Function
Select measured value
00:
01.2
°C
Function
Zero-point adjustment
by pressing
<ADJ>
To execute press
PROG
Measured value
00:
00.0
°C º
Zero-point
zero-point
01.2°C
If the function is locked at level 3 or above (see
12.3.4) a help box states that it can only be un-
locked temporarily for adjustment purposes;
this ensures that the correction values are re-
main permanently stored on the connector.
For adjustment temporarily unlock by pressing
<FREE>
If a base value has been programmed, the measured value indicated
after adjustment is not zero but the negative base value.
In the case of
dynamic pressure probes
the zero-point error is al-
ways written to the calibration offset temporarily (i.e. until you switch
off) even if the channel is locked.
11.2.3 Sensor adjustment for chemical sensors and probes
With the following sensors in the measured value function press
<ADJ>
(see
11.2.2) to automatically reach the wizard menu
sensor adjustment
for
two-
point adjustment
of the
zero-point
and
gain
. The appropriate calibration set-
points should already be entered but these can also be modified.
Probe
Type
Zero point Gain
pH probe
ZA 9610-AKY:
7.00
4.00
10.00
pH
or
pH
Conductivity
FY A641-LF:
0.0
2.77mS/cm
FY A641-LF2:
0.0
147.0µS/cm
FY A641-LF3:
0.0
111.8mS/cm
O
2
saturation
FY A640-O2:
0
101 %
Temperature and atmospheric pressure can also
be entered here if necessary for compensation
purposes (see 11.2.5, 11.2.6).
ALMEMO
®
5690-2M
33
SENSOR ADJUSTMENT
±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±
Select measuring channel:
01: 7.23 pH pH-Wert
Temp.Compensation:
25.0 °C
Air pressure
1013. mb
Zero point:
Setpoint 1:
7.00 pH
01: 7.00 pH pH-Wert
Slope:
Setpoint 2:
10.00 pH
01: 10.00 pH pH-Wert
Slope error:
-10.8 %
CLEAR ADJ M ESC
Sensor is locked.
To adjust temporarily unlock
by pressing FREE
To cancel press ESC
