User Manual

Control concept
Superposed plant controls
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Determining plant operating mode
A superposed plant control generally has different sources such as plant
switch, scheduler program or important fault messages, from which the
resulting plant operating mode must be determined.
The ENSEL_MS (Enable Selector Multistate) and ENSEL_BO (Enable Selector
Boolean) blocks are available for evaluating the resulting plant operating mode
in the firmware library of Desigo. As a rule, the block is placed before plant
control as illustrated in the following figure. All potential influences are
interconnected, prioritized by importance on the block and the corresponding
required plant operating mode is determined.
Example:
● A fire detector as a high priority (P04) and requires the plant operating
mode EmergOff.
● The smoke extraction switch has the highest priority (P01) and demands
plant operating mode smoke extraction.
● The scheduler has a low priority (P11) and demands plant operating modes
Stage 1, Stage 2 and Off.
The output [Val] for ENSEL_MS now supplies the CMD_CTL the resulting plant
operating mode for additional processing. It is important that the multistate
enumerations for both blocks ENSEL_MS and CMD_CTL are the same. The
multistate values are not text, but rather numbers based.
Superposed command control CMD_CTL
The command control CMD_CTL block is used primarily for the sequence
control in the ventilation plants. The block makes it possible to sequentially
switch on and off the aggregates. As it is implemented in a very general and
flexible way, other fields of application are also conceivable, e.g., for
refrigeration plants.