User manual for RTD,TC,mV/4-20mA converter module SPT-86L
where W means the value returned in measurement register.
Fig. 6.2 Normal (”InputLow” < ”InputHigh”) and inverted (”InputLow” > ”InputHigh”)
characteristic.
6.1.3.
Square root characteristic
The normalized result is rooted and further conversion is done as for linear characteristic.
Conversion is made accordingly with the expression:
W
=
U
n
×
"InputHigh"
−
"InputLow"
"InputLow" ,
where W means the value returned in measurement register.
Showed above expression is not valid when normalized result is negative. In this
case (U
n
<0) the returned result is equal ”
InputLow
” (see graphs below).
Fig. 6.3 Normal (”InputLow” < ”InputHigh”) and inverted (”InputLow” > ”InputHigh”)
characteristic.
6.1.4.
User defined characteristic
User defined characteristic is defined as set of X-Y points. Number of the points is variable and
may be set from 2 to 20 points which make linear segments (see figure below and ”
UserChar
”
group of registers). Due to the normalized result U
n
, the device computes specific segment,
e.g. for characteristic from figure below, and U
n
= 0,65 the segment between points X = ”
50.0.
”
and X = ”
70.0.
” will be chosen.
Let's mark those points as PL (point low) i PH (point high) - in this example PL= ”
50.0.
” and PH
= ”
70.0.
”, and the normalized result U
n
for the point PL as U
p
(in this example U
p
= U
n
(PL) =
13
R
e
tu
rn
e
d
va
lu
e
Input voltage [mV]
-25
0
25
50
75
100
InputLow
InputHigh
R
e
tu
rn
e
d
va
lu
e
Input voltage [mV]
-25
0
25
50
75
100
InputHigh
inputLow
i
R
e
tu
rn
e
d
va
lu
e
Input voltage [mV]
-25
0
25
50
75
100
InputLow
InputHigh
R
e
tu
rn
e
d
va
lu
e
Input voltage [mV]
-
25
0
25
50
75
100
InputHigh
InputLow
