Echelon i.LON SmartServer 2.0 - Manual (Page 55)

i.LON SmartServer 2.0 Programmer’s Reference 4-14
Property Description
A flag indicating whether the data point is hidden or shown in the
navigation pane on the left side of the SmartServer Web interface.
This property may have the following values:
0 – shown
1 – hidden
A timestamp indicating the last time the configuration of the data
point was updated. This timestamp uses the ISO 8601 format,
which is as follows:
YYYY-MM-DDTHH:MM:SS.sssZPhh:mm
The current value in the data point. This property may also include
the following attributes:
• LonFormat (format description). The format defined by the
data type used by the data point. This attribute is expressed in
the following format: "#<programID>[scope].<data type>".
• LonFormat="UCPTvalueDef". The value definition currently
being used by the data point. Value definitions represent
preset values. They can be created with the Configure – Data
Points Web page in the SmartServer Web interface, or with
the Set function. You can use these value definitions to update
the value of the data point other SmartServer applications such
as the Event Scheduler or the Alarm Notifier.
• Unit. The units of measure used by the data point.
The current status of the data point. This can be used when setting
up Alarm Generators and Alarm Notifiers with the SmartServer.
For more information on these applications, see Chapter 6, Alarm
Generator, and Chapter 7, Alarm Notifier.
The priority level currently assigned to the data point (0-255). The
priority level of a data point determines which applications can
write to its value. You can modify the value of this property with
the Write or Invoke functions.
4.3.4.1 Setting the Maximum Age of Data Point Values
When you use the Read function to read the value of a data point on the Data Server, you can specify a
property to set the maximum period of time (in seconds) that data point value is cached in the Data Server before it polls
the data point and returns an updated value. This enables you to control the amount of traffic that is generated on a
specific channel by your SOAP application.
The value to which you set is compared to the amount of time a data point value has been cached in
the Data Server, which then does the following:
• If is less than the period of time the data point value has been cached, the Data
Server polls the data point and returns the updated value.
• If is greater than the period of time the data point value has been cached, the
Data Server returns the cached value.