User Manual

Automat
ion stations
Functions
18
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18 Automation stations
The Desigo PX range is based on freely programmable automation stations.
They provide the infrastructure to accommodate and process system-specific
and application-specific functions. The PX range of automation stations
comprises the compact and modular series.
See
Desigo PX - Automation system for HVAC and building services - System
overview
(CM110756).
See
Automation stations modular series PXC..D, PXC..-E.D, PXA40-..
(CM1N9222).
See
Automation stations compact model PXC..D (CM1N9215).
Control Functions
The D-MAP programming language lets you program and parameterize plants,
using function blocks and compounds. The graphics-based data-flow
programming in Xworks Plus (XWP) lets you implement all the necessary
control strategies for optimum operation.
System Functions
The distributed functions, which ensure the overall functioning and inter-
operation of all plants, are described in the following chapters and documents:
● For alarm strategy, see chapter
Alarm Management .
● For time scheduling, see chapter
Calendars and Schedulers .
● For access rights and user designations, see
IT Security in Desigo
Installations (CM110663).
● For emergency operation and forced control, see chapter
Control Concept .
● For wiring tests with Desigo Point Test Tool, see chapter
Desigo Workflow,
Tools and Programming .
Cyclical Processing
One PX automation station contains one downloaded D-MAP program. A D-
MAP program cannot run on two automation stations, that is, there are no
overlapping programs across automation stations. A downloaded D-MAP
program does not run automatically. It must be started explicitly and is
executed in accordance with the cyclical processing principle, that is, all D-
MAP blocks in an automation station are processed in a repeating cycle.
A minimum and maximum cycle time is defined for each automation station. If
the processing of all blocks is:
● Shorter than the minimum cycle time, the next processing cycle is delayed
until the minimum cycle time has elapsed.
● Longer than the maximum cycle time, the next processing cycle starts as
soon as possible.
The processing order of the individual blocks:
● Does not depend on their arrangement on the plan (D-MAP program)
● Can be set explicitly when creating the D-MAP program
The values at the physical inputs and outputs are displayed in the automation
station via the process image. There are two instances of the process image:
● The frozen process image does not change during a processing cycle. D
MAP programs only read from or write to this instance of the process
image.
● The active process image is continuously connected to the real plant.
Cycle time
Process image