1 internal structure of a filter link, 1 fixed link (type 16), 1 internal structure of a filter link -4 – ElmoMC SimplIQ Software Manual User Manual
Page 213: Fixed link (type 16) -4, Simpliq, Dcs es b as es b d
SimplIQ
Software Manual
13BFilters
MAN-SIMSW (Ver. 1.4)
14-4
14.1 Internal Structure of a Filter Link
There are two types of filter links:
Type 16, a fixed link for which the next four link parameters are the filter coefficients.
Type 26, a scheduled link, for which the next four link parameters are not used. The four
filter coefficients are selected at run-time from the filter bank.
A filter link has five parameters:
Element Description
Comment
0
Type
16 for fixed links
24 for scheduled links
1…4 Filter
coefficients
k
1
, k
2
, k
3
and k
4
Used only for fixed blocks
The parameters k
1
, k
2
, k
3
and k
4
are stored inside the
SimplIQ
drive as integers. As a
result, when you read back these coefficients, they may have slightly different values
than those that you programmed.
14.1.1 Fixed Link (Type 16)
The basic continuous-time second-order element is a filter with a unity DC gain:
D
Cs
Es
B
As
Es
B
D
2
2
+
+
+
+
⋅
Note that this element is very general: It can be used, for example, as a notch filter, a low-
pass complex pole filter, a double-lead element or a single pole.
The equivalent discrete form is:
2
1
2
2
1
2
0
a
z
a
z
b
z
b
z
b
+
+
+
+
Order Parameter Description
Comment
1
k
1
b
0
+ b
1
+ b
2
Float, represented by a long value
2
k
2
-(b
1
+ b
2
)
Float, represented by a long value
3
k
3
-b
2
Float, represented by a long value
4
k
4
a
2
Float, represented by a long value
Table
14-6: Fixed Link Parameters
The parameter a
1
is obtained explicitly by a
1
= b
1
+ b
1
+ b
1
-
a
1
- 1.