Micromod RetroPAK: SLC Configuration Manual - Manual (Page 216)

Command Series Migration to MOD 30ML
Function Code 3 - Lead / Lag
EXPLANATION
Function code 3 causes the output of the function block to lead or lag changes in the input
signal <S1>. The following equation describes the operation:
OUTPUT = OLDOUT +
LEAD * (IN- OLDINP)
(LAG + SCAN)
SCAN * (IN - OLDOUT)
( LAG + SCAN)
+ OUTPUT = OLDOUT +
LEAD * (IN- OLDINP)
(LAG + SCAN)
SCAN * (IN - OLDOUT)
( LAG + SCAN)
+
This is programmed in to the LEAD/LAG expression block as below:
Y = YL +
S3 * ( S1 - S1L)
S4 + DT
+
DT * (S1 - YL)
S4 + DT
Y = YL +
S3 * ( S1 - S1L)
S4 + DT
+
DT * (S1 - YL)
S4 + DT
INPUTS - OUTPUTS
Signal Type Block Description
S1 Input – S1
Floating Point FC3 Connect to the FC3.S1 signal of the
compound. Input to the Lead/Lag function.
Input – S1L
Floating Point LEAD/LAG Value of the last input (input of the previous
cycle)
Input – S3
Floating Point Time Constant T1 (Lead) in seconds
Input – S4
Floating Point Time Constant T2 (Lag) in seconds
Input – Y
Floating Point Present Output value
Input – YL
Floating Point Value of the last output (output of the
previous cycle)
Input – DT
Floating Point Scan (Module cycle time) in seconds
N Output – R
Floating Point LEAD/LAG Connect from the LEAD/LAG.N signal of
the compound. Output from the LEAD/LAG
block is the result of the lead / lag calculation.
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