INTEGRATOR block
Short summary
Name |
INTEGRATOR |
→POU type |
|
Category |
|
Conform to →IEC-standard |
not defined in IEC-standard |
Graphical interface |
|
Available since |
version 1.47.0 (for logi.CAD 3) |
Functionality
This is a control technical transfer function of a discrete integral element
with trapezoidal rule
approximation
.
Here the input values are not added up as in the
rectangle rule approximation, but the block uses the region of the generated trapezoid generated from the current value and the previous value. This approximation tends to be more accurate – in particular in case of exponential and ramp functions
.
Enter the input value at input IN. Enter the integral action time constant at input TI. During the first cycle after a restart of the application, the output OUT remains set to value 0. Setting the input P to the value FALSE (or an equivalent) only considers negative input values (locks the upper integration direction), whereas setting the input N to the value FALSE only considers positive input values (locks the lower integration direction). If FALSE is connected to both inputs P and N, both integration directions are locked and the value of the output OUT does not change. Setting the input R to the value TRUE resets the output OUT to the value 0. Only if the input R is set to the value FALSE, the integration is started.
The following formular describes the digital implementation:
Internal values: t ... current time, tA ... time since last call of block
In-/outputs
|
Identifier |
Description |
|
Inputs: |
IN |
LREAL |
input |
TI |
TIME |
integral action time constant |
|
P |
BOOL |
locking the positive integration direction |
|
N |
BOOL |
locking the negative integration direction |
|
R |
BOOL |
reset |
|
Outputs: |
OUT |
LREAL |
integration value |
Input EN and output ENO are available when →calling
the block. See "Execution control: EN, ENO" for information on input EN and output ENO.
Internal error diagnostic for block
If the integral action time constant is less than the time period that has passed since the last block call , the output OUT is reset to the value 0 and the outpunt ENO is reset to the value FALSE . In case of an error the value of the ENO output will be set to value FALSE (or an equivalent).
Example for usage within ST-editor
PROGRAM ExampleIntegrate
VAR
iIntegrator : INTEGRATOR;
END_VAR
// Note: P and N have to be set explicitly to TRUE, because the default value (FALSE) would lock both integration directions.
iIntegrator(IN :=
1
, P := TRUE, N := TRUE);
END_PROGRAM
When creating your application within the ST-editor, enter a call of a block by typing the text as requested by the syntax or use Content Assist.