Siemens SIMATIC Manual page 69

After a warm restart on the CPU, the controller is in manual with the heating off.
If you want to tune the controller, set the TUN_ON bit and enter a setpoint at SP.
You can monitor the tuning at the PHASE parameter.
The result of the tuning can be seen at the status words STATUS_H and
STATUS_D.
Putting the Sample into Operation
To put the sample into operation, follow the steps outlined below:
1. Copy the sample to a CPU.
2. In HW Config, set the cycle time of OB35 to 20 ms.
If a time error occurs in the cyclic interrupt level, you must extend the cycle
time. In this case, the simulation will run more slowly. When you control the
real process, the cycle time of OB35 and the sampling time CYCLE_P or
CYCLE of DB_PROC_P must match.
The screenshot below illustrates controller tuning with FB58:
zEn
13
Process value
This screenshot shows the controller tuning when heating from ambient
temperature 20°C to the operating point (70°C). Following this, a setpoint step
change was controlled with a control zone. At the new operating point of 90°C, the
controller was tuned again with negative manipulated variable excitation.
PID Temperature Control
A5E00125039-02
Examples for the Temperature Controllers
Setpoint
Process value
Manip. variable
Zoom
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