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).
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.
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.
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.
Values read in cycle 1 are processed in cycle 2. Output values calculated in cycle 1 are transferred to the peripherals in cycle 2.