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Orbisphere 510/511/512 Analyzers - Inputs/Outputs Menu 77 of 138
Operator Manual
ORBISPHERE
6.5 Analog Output Characteristics
The analog output characteristics can be set to either Mono Linear, Tri Linear or None.
6.5.1 “Mono Linear” Analog Output
The "Mono Linear" output is the default setting for each analog output. It is illustrated in
Fig 6-3 below (4-20 mA output is shown, 0-20 mA or 0-5 V settings are similar).
The goal of this setting is to use all the points available on the slope from 4 mA to 20 mA
to show the range of measurements that are usual in the measured process. Setting the
output this way allows for the highest signal resolution for the actual conditions.
The downside is that any measures below the set range will have the same analog signal
locked at 4 mA. Similarly, any measure over the set range will have the same analog
signal locked at 20 mA. Settings must made by balancing these aspects.
Fig 6-3:
“Linear” Characteristics Diagram
Settings
For each output, set ML and MH in the current measuring unit (e.g. °C for a temperature
output). When a compound unit is selected the smallest unit will be used (e.g. ppb for a
"ppm-ppb" compound unit).
These points should be set keeping in balance the following conditions (see Fig 6-3
above):
• The smaller is Range 1, the better is the analog signal resolution within the
expected range of measure.
• In Range 0 the analog outputs only shows that measurement is below the ML
value. Similarly in Range 2 the analog output only shows that measurement is
over the MH value.
The formula to compute the measurement knowing the current I (or voltage U) and the
resolution R is given in the following table:
Output type
Linear:
Range Measurement M Resolution R
4-20 mA 20 > I > 4
M = ML + (MH - ML)
*
(I - 4) / 16 R = (MH-ML) / 808
0-20 mA 20 > I > 0
M = ML + (MH - ML)
*
I / 20
R = (MH-ML) / 1010
0-5 V 5 > U > 0
M = ML + (MH - ML)
*
U / 5
R = (MH-ML) / 1010