Example With Fb 58 "Tcont_Cp" (Pulse Control) - Siemens SIMATIC Manual

Examples for the Temperature Controllers
Code of the Samples
The samples are written in STL. You can view them directly in the LAD/STL/FBD
editor. In this editor, select View > Display with "Symbolic Representation",
"Symbol Selection" and "Comment". If you have enough space on the screen, you
can also display the "Symbol Information".
Using a Sample
The sample programs include variable declaration tables (VAT) with which you can
see and change the values. With the curve recorder in the parameter assignment
user interface, you can also check the curves.
Adapting a Sample
You can use the code of the samples directly as a user program, however, the
samples are not tuned for a real process.
6.2

Example with FB 58 "TCONT_CP" (pulse control)

The "pulse controller" sample contains a simple control loop with the FB 58
"TCONT_CP" temperature controller and temperature process simulated with
PROC_P. The controller is set up as a pulse controller. PROC_P represents a 3rd
order lag with a binary input.
The following schematic shows the control loop of the sample:
SP
PV
Program Structure
The controller and process block are called in OB35 with a cyclic interrupt time of
20 ms. The slower controller stage operates with CYCLE = 400 ms. To achieve the
required accuracy, PER_TM > CYCLE was selected (1 s).
When OB100 starts, the restart bits of the controller and process are set.
The pulse generator for the controller is activated in OB100.
6-2
QPULSE
TCONT_CP,
DB_TCONT_CP
HEAT_P
PROC_P,
DB_PROC_P
OUTV
PID Temperature Control
A5E00125039-02