L-INX User Manual 94 LOYTEC
Version 4.0 LOYTEC electronics GmbH
the CEA-709 router in the L-INX needs to be commissioned. See Chapter 7 for more
information on the built-in router and configuration server.
5.4.2 CEA-709 Data Points
Data points in the CEA-709 network are known as network variables (NVs). They have a
direction, a name, and a type, known as the standard network variable type (SNVT) or user-
defined network variable type (UNVT). In addition to NVs, also configuration properties
(CPs) in the CEA-709 network can be accessed as data points. Both standard CP types
(SCPTs) and user-defined CP types (UCPTs) are supported.
The typical procedure in configuring the device consists of the following steps:
1. Select the data points of the network to be used on the device (e.g., select the NVs in
the CEA-709 network nodes)
2. Create necessary registers, math objects
3. Select those data points on the device, which shall be exposed as OPC tags or the PLC
The CEA-709 NVs on the device can be created in three different ways:
Static NV: For each selected NV on the network there is a static NV created on the
device. This NV can be bound to the NV on the network. Note that adding static NVs
to the device results in a change to the default XIF file. The device is assigned a new
―model number‖ to reflect this change (see Section 5.4.3). Static NVs are the way to
use NVs in non-LNS systems, where NVs shall be bound instead of using polling.
Dynamic NV: For each selected NV on the network there is a dynamic NV created on
the device. Compared to static NVs, dynamic NVs do not change the XIF interface of
the device. The dynamic NVs are created by the network management tool. Currently,
only LNS-based tools can manage dynamic NVs. As for static NVs, with dynamic NVs
it is possible to use bindings instead of polling.
External NV: The selected NVs on the network are treated as external NVs to the
device. The device doesn‘t create any NVs on the device, but instead uses polling to
read from those NVs and explicit updates to write to the NVs. Therefore, no bindings
are necessary for external NVs. For input data points using external NVs however, a
poll cycle must be configured. If not configured explicitly, a default poll cycle of 10
sec. is chosen. The default poll cycle can be changed in the project settings menu.
Based on the NV the data point is derived from, the following kinds of data points are
created:
Simple NVs that hold only one scalar value, e.g., SNVT_amp: Those kinds on NVs are
represented as analog data points. The data points holds the current value, NV scaling
factors are applied.
Simple NVs based on an enumeration, e.g., SNVT_date_day: Enumeration types result
in multi-state data points. They represent the state of the NV.
Structured NVs that consists of a number of fields, e.g., SNVT_switch: All structured
NVs are represented as user point. That is, the data point is structured similar to the NV
it is based on. Beneath the user data point, the individual structure fields are presented
as ―sub-data points‖.
For more information on the different types of network variables and their implications
please refer to the application note in Section 17.2. For CPs the allocation type ―File‖ is
used.
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