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Function Blocks
LDLG Lead/Lag Function Block
Revision 11
HC900 Hybrid Control Designer Function Block Reference Guide
179
2/07
LDLG Lead/Lag Function Block
Description
The
LDLG
label stands for
Lead/Lag.
This block is part of the
Auxiliary
category.
Function
Modifies an analog input value (X) to include LEAD (T2) and LAG (T1) time constants of from 0 to 99
minutes, when a digital input (EN) is ON.
•
If EN = ON, then:
OUT =
1 + sT2
1 + sT1
x X
s = Laplace operator
If T1 = 0, then:
OUT = last X +
T2
t
(X - last X)
last X = Input value from execution cycle.
t
= Duration of previous cycle time in minutes.
If T2 = 0, then the block functions as a digital lag filter.
•
If EN = OFF, or initial start, then:
OUT = X.
Inputs
X
= Analog value (Primary Input)
EN
= Digital signal (Enable)
Output
OUT
= Analog value as modified
Содержание HC900
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