Siemens SIMATIC S7-400 Configuration And Use Manual page 63

PID Temperature Control
PID Temperature Control consists of two function blocks (FBs), which contain the
algorithms for generating control and signal-processing functions for temperature
controllers.
The respective blocks are used to assemble the following controllers:
• Temperature controller for actuators with a continuous or pulsed input signal.
This controller block also includes a self-tuning function for the PI/PID
parameters.
• Temperature step controller for actuators with an integral component such as a
positioning motor.
The temperature controller operates with the PID control algorithm and features
additional functions for temperature processes. The controller supplies analog
manipulated values and pulse-duration modulated actuating signals. The controller
outputs signals to one actuator; in other words, you can use the controller for either
a pure heating process or a pure cooling process.
To improve the control response, the block includes a control zone and reduction of
the P component if there is a setpoint step change. The controller can set the
PI/PID parameters itself using a controller tuning function.
The temperature step controller operates with the PI control algorithm of the
sampling controller, supplemented by function groups for generating the binary
output signal from the analog actuating signal. You can also use the controller in a
cascade control as a secondary position controller, for example, for temperature
control with heating power regulation using pulse-break activation and cooling
control using a butterfly valve.
You can externally influence the manipulated value signals of the temperature step
controller. The step controller operates without a position feedback signal.
PID Self-Tuner
The PID Self-Tuner enables you to expand the following PID controllers from
SIMATIC S7 to create self-tuning PID controllers.
• Standard PID Control
• Modular PID Control
• Controller module FM 455
PID Self-Tuners are particularly useful for the following:
• Temperature controls
• Liquid level controls
• Flow controls (not for pure control value regulation)
Automation System S7-400 Configuration and Use
A5E00442711-02
Technological Functions of the S7-400
4-15