Zero-Point Adjustment; Sensor Adjustment For Chemical Sensors And Probes - Ahlborn ALMEMO 5690-2M Operating Instructions Manual

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
Function Zero-point adjustment by pressing
To execute press
Measured value
Zero-point
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
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
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
pH probe ZA 9610-AKY:
Conductivity FY A641-LF:
FY A641-LF2:
FY A641-LF3:
O saturation FY A640-O2:
2
Temperature and atmospheric pressure can also
be entered here if necessary for compensation
purposes (see 11.2.5, 11.2.6).
Measured value correction and compensation
Zero point Gain
pH or
7.00 4.00
pH
10.00
0.0 2.77mS/cm
0.0 147.0µS/cm
0.0 111.8mS/cm
0 101 %
00: 01.2 °C
<ADJ>
PROG
00: 00.0 °C
zero-point
Sensor is locked.
To adjust temporarily unlock
by pressing FREE
To cancel press ESC
<FREE>
SENSOR ADJUSTMENT
±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±
Select measuring channel:
01: 7.23 pH pH-Wert
Temp.Compensation:
Air pressure
Zero point:
Setpoint 1:
01: 7.00 pH pH-Wert
Slope:
Setpoint 2:
01: 10.00 pH pH-Wert
Slope error:
CLEAR ADJ M
ALMEMO ® 5690-2M
º
01.2°C
<ADJ> (see
25.0 °C
1013. mb
7.00 pH
10.00 pH
-10.8 %
ESC
33