L-INX User Manual 85 LOYTEC
Version 4.0 LOYTEC electronics GmbH
5.1.2 Timing Parameters
Apart from the meta-data, data points can be configured with a number of timing
parameters. The following properties are available to input or output data points,
respectively:
Pollcycle (input): The value is given in seconds, which specifies that this data point
periodically polls data from the source.
Receive Timeout (input): This is a variation on the poll cycle. When receive timeout is
enabled, the data point actively polls the source unless it receives an update. For
example, if poll cycle is set to 10 seconds and an update is received every 5 seconds, no
extra polls are sent.
Poll-on-startup (input): If this flag is set, the data point polls the value from the source
when the system starts up. Once the value has been read, no further polls are sent unless
a poll cycle has been defined.
Minimum Send Time (output): This is the minimum time that elapses between two
consecutive updates. If updates are requested more often, they are postponed and the
last value is eventually transmitted after the minimum send time. Use this setting to
limit the update rate.
Maximum Send Time (output): This is the maximum time without sending an update.
If no updates are requested, the last value is transmitted again after the maximum send
time. Use this setting to enable a heart-beat feature.
5.1.3 Default Values
Default values can be defined for data points when needed. The value of a data point will be
set to the defined default value, if no other value source initializes the data point. Default
values are beneficial, if certain input data points are not used by the network and need a pre-
defined value, e.g., for calculations. Default values are overridden by persistent values or
values determined by poll-on-startup.
5.1.4 Persistency
Data point values are by default not persistent. This means that their value is lost after a
power-on reset. There exist different strategies for initializing data points with an
appropriate value after the device has started.
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
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