Central functions

The configurable DXR2 room automation provides the following central functions. The functions are used to coordinate supply and demand signals for the entire building or large sections thereof between the rooms and generation plants.

  • Central operating groups including room operating mode, setpoints, and seasonal compensation, lighting, shading, and emergency commands
  • Demand-dependent hot water supply system with temperature setpoint
  • Demand-dependent cooling water supply system with temperature setpoint, adjustment to prevent condensation, and calculating free cooling
  • Demand-dependent 2-pipe supply system for heating/cooling water including temperature setpoint, changeover, and calculation of free cooling
  • Demand-dependent air handling unit (supply and extract air) including temperature setpoint, maximum humidity setpoint, pressure setpoint, maintaining a minimum central air flow, calculating air flow deviation, and cumulative air flow setpoints
  • Demand-dependent heat pump supply system
  • VAV emergency group including shutdown, fume hood, pressure development, or purge
  • Information of central weather station includes outside air temperature, outside brightness, solar radiation, wind speed, and precipitation
  • Central facade functions for shading, including brightness calculation, central operating group for facade, or anti-glare protection calculation
  • Central shading protection group for wind, precipitation, and frost protection, staged distribution of blinds commands in large buildings

Load central functions on a DXR2.E/M18

The central functions are available to the DXR2.E/M18. This application type is not preloaded at the factors, but rather must be downloaded for a specific project to one or more DXR2.E/M18s.

As a rule, all central functions can be configured on a DXR2. All central functions can be selected and configured on the application type for central functions. Various aspects on a project define how many DXR2 are used with central functions:

Required I/Os

The planned use of onboard inputs for the applicable central functions (e.g. outside temperature sensor for HVAC supply function, wind sensor for facade protection function, etc.) determines possible distribution of central functions to multiple automation stations.

Required supply groups

One DXR2 with central functions can control the following number of supply groups:

  • 4 x controls for a facade with 4 facade segments each (3 of which can be delayed)
  • 4 x groups for distributing room operating mode to rooms
  • 2 x hot water supply groups
  • 2 x chilled water supply groups
  • 1 x air supply group (based on demand)
  • 1 x heat pump supply group
  • 2 x HVAC emergency controls (off, positive pressure, negative pressure, or purge)
  • 2 x groups for central control of light and all facades with 4 facade segments each (3 of which can be delayed)
  • 1 x group for emergency control of facades with 4 facade segments each
    (3 of which can be delayed)
  • 1 x group for protection of facades with 4 facade segments each
    (3 of which can be delayed)
  • 1 x group for service function of facades with 4 facade segments each
    (3 of which can be delayed)
  • 1 x group for emergency control of all luminaires

Sensor placement

Connect all sensors directly to the DXR2 for central functions via analog or digital I/Os. A DXR2 for central functions may be required at multiple locations in the building depending on the position of the sensors (e.g. wind sensors). The functions belonging the sensors must be configured on each DXR2 to which the corresponding sensor is connected.

Recommendation

Four different configurations for central functions are recommendation to simplify configuration. The four configurations are described in the following sections. Each of the configurations can be used and installed multiple times on a project (e.g. if more HVAC hot water supply groups are required).