LOYTEC L-Proxy User Manual Download

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L-Proxy User Manual

LOYTEC

Version 3.1

LOYTEC electronics GmbH

For input data points, the value can be actively polled from the network when starting up.
Use the Poll-on-Startup feature for this behavior. Polling the network values has the
advantage that intermediate changes on the network are reflected. An input data point can
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.

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.

6.3.5 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.

6.3.6 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 =

N +

where N is the network value,

the

custom scaling factor

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.