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5.4
Process data and operation modes
5.4.1
Data stream and calibration
Data stream
The flow chart at the bottom (Fig. Data stream representation of the EL31xx) illustrates the data stream in
the EL31xx (processing of the raw data).
Fig. 103: Data stream representation of the EL31xx
Calculation of process data
The concept "calibration", which has historical roots at Beckhoff, is used here even if it has nothing to do with
the deviation statements of a calibration certificate. Actually, this is a description of the vendor or customer
calibration data/adjustment data used by the device during operation in order to maintain the assured
measuring accuracy.
The terminal constantly records measured values and saves the raw values from its A/D converter in the
ADC raw value object 0x80nE:01 [} 86]. After each recording of the analog signal, the correction calculation
takes place with the vendor and user calibration data as well as the user scaling, if these are activated (see
fig. Data stream representation of the EL31xx [} 99]).
Calculation
X
= f(X
)
F
ADC
-14
Y
= (X
– B
) x A
x 2
H
ADC
H
H
-14
Y
= (Y
– B
) x A
x 2
A
H
A
A
-16
Y
= Y
x A
x 2
+ B
S
A
S
S
EL3182
Designation
Output value after the filter
Measured value after vendor calibration,
Measured value after vendor and user calibration
Measured value following user scaling
Version: 1.2
Commissioning
99
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