Allen-Bradley ProcessLogix 1756-IA16, Справочное руководство, Страница: 46 / 120

Publication 1757-RM810A-EN-P - May 2002
3-6 Functional Blocks
GENLIN (General Linearization)
LEADLAG (Lead Lag)
Description Calculates an output value (PV) as a function of the input value (P1) based on a separate function that can be
represented by 2 to 13 user-defined coordinates. (You specify the IN and OUT values of each coordinate to make a
segment.) The input value (P1) is then compared with the input range of each segment and the output is set at the
intersection of the input with the appropriate segment.
Function Typically used to provide a linearized PV (in engineering units) for a sensor with nonlinear characteristics. Block can
also be used to characterize functions of a single parameter, such as heat transfer versus flow rate, or efficiency as a
function of load. It is particularly useful when the relationship of the input to engineering units is empirically
determined.
Inputs One input value (P1) is required:
•
P1 must be fetched from another function block.
•
Number of process input connections is 1.
Outputs PV and its status, PVSTS, as well as a Boolean flag, PVSTSFL.BAD, to indicate to other function blocks, that this
block’s PV status is bad.
Segment
Extension The first and last segments are treated as if they are infinitely extended. This means, if P1 is less than IN [0] or greater
than IN (NUMSEGS), PV is computed by assuming that the slope in the appropriate segment continues from the
intersection point.
Parameters DESC
IN [0..12]
NUMSEGS
ORDERINCM OUT [0..12]
P1
P1STS
PV PVFORMAT
PVSTS
PVSTSFL.BAD
PVSTSFL.MAN PVSTSFL.NORM
PVSTSFL.UNCER
PVVALSTS
Description May be configured to apply a lead-time and two lag-time compensation factors to a process input value.
Function Provides dynamic lead-lag compensation to the P1 input. It supports one lead compensation and two lag
compensation factors. There is a time constant for each compensation factor. Specifying a zero value for any time
constant will suppress the corresponding compensation.
Inputs One input value (P1) is required:
P1 must be fetched from another function block.
Outputs The following output is produced:
PV and its status, PVSTS and PVSTSFL
Equations This function block only supports one equation – a single input filtered with one lead compensation and two lag
compensations. There is a time constant for each compensation factor. Specifying a zero value for any time constant
will suppress the corresponding compensation.
Parameters CPV
DESC
DPV
INITREQ
LAG1TIME LAG2TIME
LEADTIME
ORDERINCM
P1
P1STS PV
PVFORMAT
PVSTS
PVSTSFL.BAD
PVSTSFL.MAN PVSTSFL.NORM
PVSTSFL.UNCER
PVVALSTS