IM 12D7B2-E-H
13
1. What is the output range?
The display will always show the full range of
the instrument from 0-2000 mS/cm.
Maximum resolution is assured by autorang-
ing, where the position of the decimal point
and the measuring units (microSiemens/-
milliSiemens) are moved to best fit the actu-
al value.
For control or recording the current output
can be ranged to a specific part of the total
measuring span. When selecting the
measuring range care must be taken to use
the appropriate conductivity cell. For any
given cell constant there is a defined range
of operation which should not be exceeded.
From the factory the instrument has a linear
output range 0-1 mS/cm in combination
with a cell constant C=0.1 cm
-1
.
Other linear ranges can be programmed in
this routine. It is also possible to program
non linear output ranges for specific applica-
tions. These are programmed in the service
level, see sections 7-5 and 7-6.
2. Programming a linear output range
A linear output range is programmed by
entering two values:
- 0% the conductivity at the start of the
output range which corresponds
to 4 mA
- 100% the conductivity at the end of the
output range which corresponds to
20 mA.
When programming a range which does not
start at zero conductivity, take care to
respect the minimum value corresponding
to 60% of the maximum value.
3. Example
The EXA SC200 has an output table which
can be programmed to give any non-linear
output characteristic. Activation of this table
is described in §7-5. Once the table is acti-
vated the linear OUTPUT routine will no lon-
ger have any effect and will not be accessi-
ble in the commissioning menu.
Programming of the 21 step table is descri-
bed in § 7-6.
Non-linear outputs are commonly used for
measurements in pure water where high
resolution is required over a small range
combined with trend indication over a larger
range. Common forms of output for these
applications are given in §7-17.
The non-linear output can also be used to
follow a concentration curve for a specific
product. Care must be taken to ensure that
the temperature compensation is also set
up for the measured fluid under representa-
tive conditions. It should also be noted that
conductivity measurements are not specific,
so it can be influenced by impurities present
or changes in the fluid composition.
4. Other possibilities
Programming a percent by weight indication
on the second display line §7-13
4-2. Output range adjustment
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