L-INX User Manual
86
LOYTEC
Version 4.0
LOYTEC electronics GmbH
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.
5.1.5 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 LWEB 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-821 master parameter editor
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-
821 Master Parameter Editor manual.
5.1.6 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 and output) 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. If send-on-delta is active, value
changes only 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 zero, all updates are considered.
5.1.7 Custom Scaling
Custom scaling is applied to all analog data points when they communicate values to or
from the network. This feature can be used, if a network data point has engineering units not
suitable for the application (e.g., grams instead of kilograms). The scaling is linear and
applied in the direction from the network to the application as:
A =
k
N +
d
,
where N is the network value,
k
the
custom scaling factor
,
d
the
custom scaling offset
, and
A the application value. When sending a value to the network, the reverse scaling is applied.
If this property is enabled, the analog values are pre-scaled from the technology to the data
point. The custom scaling is in addition to any technology-specific scaling factors and can
be applied regardless of the network technology.
5.1.8 System Registers
The device provides a number of built-in system registers. They are present without a data
point configuration. The system registers, such as the System time or the CPU load, can be
