Sample For Fb 59 "Tcont_S" (Step Controller) - Siemens SIMATIC Manual

6.5

Sample for FB 59 "TCONT_S" (Step Controller)

The "step controller" sample contains a simple control loop consisting of a PI step
controller and a third-order lag with an integrating actuator as the model for a
temperature process.
The schematic below illustrates the control loop of the sample:
SP
PV
Program Structure
The controller and process are called in OB35. When OB100 starts, the restart bits
of the controller and process are set.
Process Block for Simulation of a Temperature Process
The block simulates a process with a 3rd order time lag. For temperature
processes select 2nd order time lag response with one large and one small time
constant (TM_LAG1 = 10 × TM_LAG2 and TM_LAG3 = 0 s).
The following schematic is the block diagram of the PROC_S controlled process
with actuator:
INV_UP
INV_DOWN
MTR_TM
DISV GAIN
+
PID Temperature Control
A5E00125039-02
QLMNUP
TCONT_S,
DB_TCONT_S
QLMNDN
LMNR_HLM
LMNR_LLM
TM_LAG1 TM_LAG2
Examples for the Temperature Controllers
INV_UP
PROC_S,
DB_PROC_s
INV_DOWN
LMNR
QLMNR_HS
QLMNR_LS
TM_LAG3
OUTV
AMB_TEM
+
OUTV
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