User Manual

Mapping works in both directions, i.e. commands can flow from BACnet to OPC

and vice versa. To map the OPC items to BACnet objects/BACnet properties an

Excel table must be configured.

A special characteristic is that the OPC values can be manipulated by means of

function blocks before mapping to BACnet. This can be used for data conversion

(signal mapping) or for value calculation (function mapping). The functions are

created within a dedicated tool, using arithmetic and logic operations, and are

available in the provided library file.

SX Open supports the system functions Alarm and Event. As with Desigo, the

properties can be configured in different ways:

• NotificationClass (alarm function and alarm class)

• BACnet Reliability, BACnet Event Enable

• High/Low Limit, Alarm Values, Fault Values

It is possible to suppress alarm bursts for each subsystem and device.

SX Open supports the system function BACnet Trend. Trending is implemented as

a relatively autonomous function using a trend server with its own data manage-

ment and operates as an independent BACnet client to the referenced SX Open

objects.

SX Open supports the system function BACnet Schedule Schedule Objects can be

defined for commanding mapped data points. For schedule exceptions Calendar

objects can be also created.

Data is exchanged between the OPC server and an SX OPC client via the

standardized Data Access interface (OPC DA specification). The OPC objects

("Items") are addressable by name, and consist of a value, a quality and a time

stamp. SX OPC maps the value to suitable BACnet objects/properties. Additionally

the OPC-quality can be mapped on the BACnet reliability.

SX OPC supports versions DA V2.x and V3.0.

SX API is Base software with "Application Programming Interface" (API) for indi-

vidual development of any application, using Microsoft® Visual Studio. With it fur-

ther 3

systems, protocols and drivers can be integrated.

Topology

Mapping signals

and functions

Alarm & Event

Trend

Schedule

OPC Data Access

SX-API:3rd-Client -

BACnet Gateway

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Siemens DESIGO™ – SX OPEN V3 CM1N9745en_05

Building Technologies 2014-06-24