User manual for RTD,TC,mV/4-20mA converter module SPT-86L
where U
inp.
means input voltage (in mV), and U
n
- normalized result.
If measured value exceeds the nominal input range (0-100 mV), and do not exceed
the permissible input range, then received normalized U
n
result will exceed 0-1
range, e.g. input range 0-100 mA and input voltage = -10 mV the normalized result
is equal -0.1, and for input voltage = 110 mV, the normalized result is equal 1.1. In
such cases presented expressions are still correct.
6.1.
ADDITIONAL CALCULATIONS (USED CONVERSION CHARACTERISTIC)
The manner of the additional computation of the returned result depends on selected
conversion characteristic. All presented charts are connected with the input range 0-100 mV.
6.1.1.
Linear characteristic
The normalized result is converted by fixed coefficients determined by ”
InputLow
” and
”
InputHigh
” parameters (when the normalized results is equal 0, then value ”
InputHigh
” is
returned, and when the normalized results is equal 1, then value ”
InputHigh
” is returned).
Expression presented below shows the manner of result calculation:
W
=
U
n
×
"InputHigh"
−
"InputLow"
"InputLow" ,
where W means the value returned in measurement register.
The value of the ”
InputLow
” parameter can be higher than the value of ”
InputHigh
”
parameter. In such a case, for an increasing value of input voltage the returned
value decreases.
Fig. 6.1 Normal (”InputLow” < ”InputHigh”) and inverted (”InputLow” > ”InputHigh”)
characteristic.
6.1.2.
Square characteristic
The normalized result is squared and further conversion is done as for linear characteristic.
Conversion is made accordingly with the expression:
W
=
U
n
2
×
"InputHigh"
−
"InputLow"
"InputLow" ,
12
R
e
tu
rn
e
d
va
lu
e
Input voltate [mV]
-25
0
25
50
75
100
InputHigh
InputLow
R
e
tu
rn
e
d
va
lu
e
Input voltage [mV]
-25
0
25
50
75
100
InputLow
InputHigh
i
i
