User Manual

Control concept
Closed-loop control strategy
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[Actg] is a characteristic parameter of the controller and indicates the relationship between the setpoint
deviation and the change in energy flow. A distinction is made between direct action and indirect [Actg].
● Direct control [Actg]: As the controlled variable rises, the controller output increases, and as the
controlled variable falls, so the controller output decreases.
Example: Cooling or dehumidification – as the measured value rises above the setpoint, so the flow of
energy is required to increase.
● Indirect control [Actg]: As the controlled variable decreases, the controller output decreases.
Example: Heating or humidification – as the measured value falls below the setpoint, so the flow of
energy is required to increase.
Inversion [Inv]
[Inv] of the output signal is required, e.g., for air dampers. The outside air and exhaust air damper must
close in response to an increasing heating demand. The inversion of the manipulated variable affects only
the output signal [Yctr] and not the action of the controller.
Sequence controller
Sequence controllers are used primarily in ventilation and air conditioning systems to control the
temperature and humidity. Other applications are also possible, e.g., in heating systems.
Each controlled aggregate functional unit incorporates a universal PID controller function block, PID_CTR,
as a sequence-controller element.
The statements made about the universal PID controller also apply to the use of the PID_CTR function
block as a sequence-controller element.
The sequence-controller elements coordinate their own interaction independently. Interaction is
coordinated with coordination signals [FmHigher] and [ToLower], which are mutually exchanged by
adjacent sequence-controller elements. This is the only link between the sequence-controller elements.
This process allows the setting of individual parameters for each individual controller or aggregate, and
hence effective optimization of the entire plant.
Properties and design of sequences and sequence controllers: