L-Gate User Manual 48 LOYTEC
Version 3.2 LOYTEC electronics GmbH
5 Concepts
5.1 CEA-709/BACnet Gateway
The operating principle of the L-Gate is to connect data points of one network technology
to data points of another technology. Data points in the CEA-709 network are known as
network variables (NVs). For more information on this technology refer to Section 5.5.
Data points in the BACnet technology are known as BACnet server objects. They have a
specific type (e.g. analog input or binary output) and a set of properties, which describe the
data point more closely. The actual value is stored in the “Present_Value”. For more
information on this technology refer to Section 5.6.
The typical task in configuring the L-Gate consists of the following steps:
1. Selecting the data points of the network to be mapped (e.g., select the NVs in the
CEA-709 network nodes or create new NVs)
2. Select or create matching counterparts of the other technology (e.g., create matching
BACnet objects)
3. Create connections between the data points (e.g. connect NVs and BACnet objects).
The connection is the central part of the gateway functionality. It defines, which data points
are mapped to which data points. Refer to Section 5.3 about the nature of connections in
the device.
5.2 Data Points
5.2.1 Overview
Data points are part of the fundamental device concept to model process data. A data point
is the basic input/output element on the device. Each data point has a value, a data type, a
direction, and a set of meta-data describing the value in a semantic context. Each data point
also has a name and a description. The entire set of data points is organized in a hierarchy.
At the data point level, the specific technological restrictions are abstracted and hidden
from the user. Working with different technologies at this level involves common work-
flows for all supported technologies.
The direction of a data point is defined as the “network view” of the data flow. This means,
an input data point obtains data from the network. An output data point sends data to the
network. This is an important convention to remember as different technologies may define
other direction semantics.
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