L-DALI User Manual
112
LOYTEC
Version 5.2
LOYTEC electronics GmbH
be made persistent, if the last received value shall be available after a power-on reset before
a poll-on-startup completes. This can be beneficial, if the remote device is temporarily
offline and the last value is considered usable.
For output data points, the value can be restored after starting up by the application. For
example, if the output data point’s value is determined by an input data point and a math
object, or the output data point is in a connection with an input, the input can poll its value
on startup. If the output data point has no specific other value source, e.g., it is a
configuration parameter set by the user, it can be made
persistent
.
To make a data point persistent, enable the Persistent property of the respective data point.
The persistency option is only available for the base data point classes analog, binary, multi-
state, string and user. More complex objects such as calendars, schedules, etc., have their
own data persistency rules. Persistency is also available for unlinked favorites.
For structured data points, only all or none of the structure members can be made persistent.
The configuration of the top-level data point, which represents the entire structure, serves as
a master switch. Setting the top-level data point to be persistent enables persistency for all
sub-data points. Clearing it disables persistency for all sub-data points.
6.1.5
Parameters
A data point can be qualified as a
parameter
data point. This is accomplished in the
Configurator software by setting a
Parameter
check box on the data point. Those parameter
data points are automatically persistent and will typically have a default value. Their
purpose is to store parameterization values, which can be changed from the default value at
run time and influence the behavior of the device or the logic running on the device. This
way, a number of devices can have the same basic configuration and be adapted by
parameter values. Examples are sunblind run times for control logic or descriptive strings
for the L-WEB visualization.
The qualified parameter data points are also exported via a parameter file, which contains
the entire set of current parameter values including meta-information for external tools to
display parameter data in a human-readable way. The LWEB-900 parameter view can
process such parameter data points and manage them for a large number of devices. For
more information on how to manage parameters on your devices please refer to the
LWEB-900 manual [5].
6.1.6
Behavior on Value Changes
The value of a data point can change, if it is written by the application or over the network.
For all data points (input, output and value) the application (connection, user control, etc.)
can be notified, when the value is written to. The property
Only notify on COV
defines,
whether the notification is done with each write or only if the value changes (change-of-
value, COV). If only notify on COV is disabled, writing the same value multiple times will
result in multiple notifications.
When the value of an output data point is updated, an update is usually sent out onto the
network. The property
Send-On-Delta
decides how the update is reflected on the network.
If send-on-delta is inactive, each update of the value is sent, even if the value does not
change. If send-on-delta is active, only value changes are sent. The send-on-delta property
is only valid for output data points.
For analog data points, the COV or send-on-delta takes an extra argument, which specifies
by what amount the value must change to regard it as a change for action. Both, COV and
send-on-delta for analog data points check the
Analog Point COV Increment
property. A
change is detected, if the value increment is bigger or equal to the specified increment. If
the property is ‘0.0’, all updates are reported, even if the value does not change.
