10. Measuring operations
25
The 1st time key
CLR
is pressed the setpoint flashes in the display.
The 2nd time key
CLR
is pressed, adjustment is performed.
To cancel adjustment press key
M
▲
3. Gain adjustment
For
gain adjustment
the
gain calibration resources must be provided
(see Table).
Gain adjustment
is then performed by pressing key
CLR
in
exactly the same way as for zero-point adjustment.
If correction val. have been programmed, the
CORR
arrow lights up.
4. Deleting adjustment values
Adjustment values can be cleared by pressing and holding down the key
CLR
. On pH probes you can thus restore the default values, base value 7.00
and gain -0.1689.
Temperature compensation
On conductivity probes and O
2
probes with an integrated temperature sensor
temperature compensation is performed automatically. For pH probes a temper-
ature sensor can be specially configured for this purpose; (see Man. 6.2.6).
10.6
Differential measurement
On version 2490-2, if two sensors with the same units and same decimal point
position are connected at measuring points M0 and M1, the difference M1 - M0
appears automatically below the measuring point M2. The sensors are electri-
cally isolated by means of photovoltaic relays. If the differential channel is not
required, it must be cleared via the interface. If further differential channels are
needed, these can also be created via the interface using the appropriate refer-
ence channels; (see Manual, Section 6.3.4).
