LTH MOD53, Operation Manual

Page: 55 / 110

9 Current Output
54
Ø Ø Ø Ø × × × ×
20.0
20.0 20.0
20.0
ppm
Current O/P Span
Span current (20mA) sensor input level
Ø
Ø Ø
Ø ×
× ×
×
On Error = No
22mA
0mA
Select state of current output when input
source error is detected (i.e. Sensor Input
Fault,
Temperature input Over range)
INPUT
The input for the current output can be one of three options. The unit can use the
sensor input or the temperature input as the source for the zero and span.
Alternatively the output can be used to drive a cleaning system (see “Cleaning”).
When the cleaning option is selected, the span and zero menus disappear and are
replaced by the cleaning option menus.
OUTPUT RANGE
The output range for the current output can be set to one of two ranges, either 0 -
20mA or 4-20mA. This selection sets the limits of the zero and span output levels.
The output will continue to provide an extrapolated output above (>20mA) and
below (<4mA) these points but will flag an error message on the main display. The
maximum current limit is approximately 22mA, the minimum limit is 0mA (i.e. the
unit cannot source a negative current)
ZERO & SPAN
The zero and span levels are set as the limits of the source input. This provides a
totally flexible method of configuring the current output. The zero can be set
anywhere within the input source range and the span up to 5% of the selected
range, providing total control of the output range and offset. An inverse
relationship can easily be achieved by simply setting the zero level to be higher
than the span level.