L-INX User Manual 201 LOYTEC
Version 4.0 LOYTEC electronics GmbH
9.1.2.5 Structured Data Points
Structured data points are modeled as one user-type data point, which contains the entire
structure value as a byte array. The respective structure fields are created as sub-data points
of appropriate class. For example, a SNVT_switch in CEA-709 would be modeled as one
user-type data point of 2 bytes length, and two sub-data points, one an analog (value
member) and one a multi-state (state member).
The relation between user-type data point and sub-data points is also exposed to OPC. In
this case, an OPC node is created for the user-type data point. In that node, the sub-data
points are exposed as OPC tags. The entire structure is also exposed as a user-type OPC tag
under the same OPC node.
Important! Deselect any un-used structure members from OPC exposure to reduce the number of
total OPC tags.
It is important to note, that when using structured data points the top-level and all its
structure members are exposed as OPC tags by default. Using many structured data points
may lead to exceeding the OPC tag limit. Please observe this limit in the Configurator‘s
statistics tab and deselect the OPC Tag check box for unwanted structure members. This
helps to keep your configuration lean and improves the performance of the OPC server
when browsing and subscribing.
9.1.3 AST Objects
The alarming, scheduling, and trending (AST) objects are more complex than regular data
points. The OPC XML-DA standard does not have appropriate tags for those objects.
Therefore, the device exposes AST objects as a set of OPC tags describing the object. All
tags for one AST object are collected under an OPC node representing the AST object.
9.1.3.1 Scheduler Object
The device exposes the scheduler objects to OPC XML-DA tags. Each scheduler object is
represented by a node in the OPC name space. The content of the schedule XML document
referred to in this section must be compliant to the scheduleCfg schema. This schema can be
found at the LOYTEC Web site. The XML documents can refer to the target namespace
‗http://www.loytec.com/xsd/scheduleCfg/1.0/‘.
In that node, the following OPC tags are available:
ServiceType (string, Read-only, const): This is a constant tag of type string, which
contains ―schedule‖. It identifies this folder as a schedule folder. This can be used as an
additional identification to the vendor-specific property of the folder tag.
Schedule (string, read/write): This tag configures the schedule. The data type is string
and the format is in XML. The XML document contains the scheduleCfg element as the
root element.
Caps (string, read-only): This tag contains the schedule capabilities. The data type is
string and the format is in XML. The XML document contains the scheduleCapabilities
element as the root element.
CalItemPath (string, Read-only, const): This is an optional tag. If present, it contains
the item path to the calendar object, that the schedule references. To read the calendar
referenced by the schedule, use this item path and the ―Calendar‖ item name to read the
calendar XML document.
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