Operation
akYtec GmbH · Vahrenwalder Str. 269 A · 30179 Hannover · Germany Tel.: +49 (0) 511 16 59 672-0 · www.akytec.de
17
17
𝑀𝑒𝑎𝑠𝑢𝑟𝑒𝑑 𝑣𝑎𝑙𝑢𝑒 = 𝐴𝑖𝑛. 𝐿 −
(𝐴𝑖𝑛. 𝐿 − 𝐴𝑖𝑛. 𝐻) ∗ (𝑆
𝑖
− 𝑆
𝑚𝑖𝑛
)
𝑆
𝑚𝑎𝑥
− 𝑆
𝑚𝑖𝑛
where
S
max
– signal upper limit (for example, 20 for 4-20 mA)
S
min
– signal lower limit (for example, 4 for 4-20 mA)
S
i
– current signal value
6.5
Digital Filter
The digital filter consists of two stages.
– Comparator is used at the first stage to detect the input signals with apparent
"gaps" or "outliers". For this purpose the filter bandwidth for the comparator
should be specified in the parameter
in.FG
in physical units. The difference be-
tween the last two measurements is compared with the bandwidth. If the differ-
ence is greater than the bandwidth, the measurement is considered to be unreli-
able and must be repeated. If an unreliable result was caused by a fault, the sec-
ond measurement confirms this and the first measurement value is ignored as an
error. If the bandwidth is set to ‘0’, the comparator is switched off.
– Damping is used at the second stage. The filter time constant should be set in
parameter
in.Fd
in seconds. The higher is the value, the higher is the noise re-
sistance and the slower is the input response. When the value is set to ‘0’, damp-
ing is switched off.
Fig. 6.2 Actual temperature T
R
Fig. 6.3 Measured temperature T
M
(filter is OFF)
Fig. 6.4 Comparator is ON
Fig. 6.5 Comparator and damping are ON
6.6
Correction
The sensor characteristic curve can be corrected by the user. Two correction parameters
are provided for each input: the offset and the slope.
– Offset can be set in the parameter
in.SH
in physical units to correct the sensor in-
itial error, for example, when you use a RTD.
– Slope can be set in the parameter
in.SL
within the range from 0.9 to 1.1.