West Control Solutions KS98-1 - Manual (Page 124)

III-6 Time functions
III-6.1 LEAD ( differentiator (No. 50))
The differentiator forms the difference quotient according to equation:
( ) ( ) ( ) ( ) { } [ ]
y t
T
T T
y t t a x t x t t y
s
s s 1 1 1 1 0
=
+
Ч - + Ч - - +
ts sampling interval x1(t) instantaneous x1
T time constant x1(t-ts) previous x1
a gain y1(t) instantaneous y1
y0 output offset y1(t-ts) previous y1
C
T
T Ts
=
+
<1
( differentiation constant )
The complex transfer function reads:
F
a T p
T p
p ( )
= Ч Ч
Ч +1
Inputs/outputs:
Digital input
reset
= 1 causes that y1= y0 and the difference quotient is set to 0.
= 0 starts differentiation automatically.
Analog input
x1
Input variable to be differentiated
Output
y1
Differentiator output
Parameters:
Parameters Description Range Default
a Gain factor -29 999...999 999 1
y0 Output offset -29 999...999 999 0
T Time constant in s 0...199999 1
Configuration:
Configuration Description Value Default
Mode
Differentiator
operation
Differentiating all changes 0 0
Differentiating only positive changes dx/dt >0, 1
Differentiating only negative changes dx/dt <0 2
9499-040-82711 Time functions
LEAD ( differentiator (No. 50)) III-124
a T
x1
reset
y1
y0 Mode
+
+ -
-
/