User Manual

Control concept
Control concept and control blocks
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5.1 Control concept and control blocks
The Desigo control concept is a set a rules that determine in general terms the principles governing all
control, reporting and monitoring operations and the switching interventions in the Desigo system. The rule
applies to block-internal control (priority array) and to functional interactions among participating blocks.
This specifically deals with:
● Structure and design of control as function blocks
● The hierarchical assignment of the function blocks among themselves
● The function hierarchy within the control chain for the function blocks
● Processing operational and fault messages
● Interventions in monitoring functions
● Impact of emergency switching
The open loop control strategy is based on the exchange of predefined signals between functional units.
Each functional unit is an image, or memory map, of an actual element of the plant, e.g., ventilation or
boiler plant.
Control functions
The open-loop control functions required for a given element are locally an integral part of the functional
unit (e.g., the increase, after a time delay, in the speed of a multi-stage fan, or the demand-based switch-
on of a boiler). In each functional unit, various possible requirements are prioritized and evaluated. The
resulting operating mode is then passed on to the elements or subordinate functional units. The functional
unit already incorporates the I/Os needed for the physical data points.