LSI LASTEM M-Log – User’s manual
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5.2.2
Acquisition from thermocouples
This feature is not available for the model ELO011.
M-Log is able to acquire the signals from many types of thermocouples. M-Log uses the internal
temperature value as reference of value of the cold junction.
In these cases it is necessary to program, by means of the
3DOM
program, the measure of the
internal temperature. The measure of the internal temperature must precede, in the measure
sequence, all measures of quantities which use such reference.
5.2.3
Details about the measure acquisition process
The sampling of the signals produced by the sensors connected to the instrument's terminal board
takes place according to the following logical procedure:
1)
Measurement of the electrical signal based on its type (voltage, resistance, frequency, etc.)
and its digital conversion into a 16-bit numeric value; the physical type of the sensor is
programmed through parameter
Electrical measure type
;
2)
Data validation: during this operation the value is limited within the scale values allowed by
the physical type of measure;
3)
Possible thermocouple value correction through the measure of the cold junction
temperature (internal temperature of the instrument);
4)
Linearization of non linear signals based on the setting of parameter
Linearization type
; the
linearization may also take place through the setting of a polynominal function whose
factors are specified until 10° degree (section
Linear parameter
of
3DOM
);
5)
Recalculation of the value according to numeric parameters defined in section
Parameters:
Computation of the measured quantity through the defined initial and final scale values;
Application of the calibration factor of the specific used sensor (radiometers, rain
gauges, etc.);
Selection of the logical state with reference to the analogue signal thresholds;
Measure validation after processing accompanied by error signalization if greater (by
0.5%) than the limits set in output; wind direction and relative humidity are excluded;
Linearized quantity control: the instrument produces null output when receiving null
input;
User scale limits.
All above parameters are indicated in section
Measure properties
in the measure modification
window of program
3DOM
.
5.2.4
Acquisition from status signals
M-Log is able to acquire different types of digital status; they have to be configured for their
connection to input number 5.
Ther are 3 different signal types: frequency signals, digital status and counters.
The default configuration of datalogger has been made for:
