Ldlg Function Block - Honeywell UMC800 Reference Manual

2.29 LDLG Function Block

Description
The LDLG label stands for Lead/Lag. This block is part of the Auxiliary category. It looks like this
graphically on the Control Builder.
Function
Modifies an analog input value (X) to include LEAD (T2) and LAG (Tl ) time constants of from 0 to 99
minutes, when a digital input (EN) is ON.
Inputs
X = Analog value.(Primary Input)
EN = Digital signal.(Enable)
Output
OUT = Analog value as modified
3/99
• If EN = ON, then: OUT =
s = Laplace operator
If T1 = 0, then: OUT = last X + T2 (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
Function Block Reference Guide
1 + sT2 x X
1 + sT1
t
= X.
Continued next page
Function Blocks
85