System information

i.LON SmartServer 2.0 Programmer’s Reference
4-15
• If <UCPTmaxAge> is set to 0, the Data Server returns polls the data point and returns the updated
value regardless how current the data point is.
• If <UCPTmaxAge> is disabled, the Data Server returns cached values regardless how old the data
point values are. This is the default.
4.3.5 Using the Write Function on the Data Server
A data point's value and priority level are initially set when the data point is added to the Data Server.
The value is set to the value established for the <UCPTdefOutput> property for the data point, and the
priority defaults to the lowest priority level (255).
You can write to a data point’s current value and priority level with the Write function. The input
parameters you supply to this function will include one or more <Item> elements that have a
<UCPTname> property, specifying the unique name of the data point to be written to with the Write
function. You should not attempt to write to more than 100 data points with a single call to the Write
function.
You can specify the value to be written to the data point with the <UCPTvalue> property. You can
also write an updated value to the data point using a formatted value, a preset, or raw hex. You can
also write values to the individual fields of structured data points.
4.3.5.1 Writing Formatted Values to a Data Point
You can use a formatted value to write to a data point. To do this, you must include a LonFormat
attribute in the <UCPTvalue> property and set it to the format description of the data point. This
attribute indicates how the <UCPTvalue> property should be unformatted by the SmartServer. If the
UCPTformatDescription of the data point being written to is SNVT_temp_f#SI, and the Write function
includes a LonFormat attribute with the value SNVT_temp_f#US, the specified value will be first
unformatted using Fahrenheit, before being written to the Data Point, even though the format of the
Data Point is normally in Celsius. For example, you could write a value of 32 to a SNVT_temp data
point in Fahrenheit by specifying the data type’s customary units (#US) format, and the value will
automatically be converted to 0.0° Celsius.
• <UCPTvalue LonFormat="#0000000000000000[0].SNVT_temp#US">32.0</UCPTvalue>
4.3.5.2 Writing Presets to a Data Point
You can use a preset to write to a data point. To do this, you must include a LonFormat attribute and
set it to the <UCPTvalueDef> property. For example, you could write a value of 100.0 1 to a
SNVT_switch data point by writing the ON preset to the data point.
• <UCPTvalue LonFormat="UCPTvalueDef">ON</UCPTvalue>
Note: If you pass in both the <UCPTvalue> property and a <UCPTvalue> property with a
<UCPTvalueDef> LonFormat attribute in a single Write function, the <UCPTvalueDef> property will
be used to determine the value to assign to the data point, unless it references an invalid value, in
which case the <UCPTvalue> property will be used to determine the value to assign to the data point.
4.3.5.3 Writing Raw Values to a Data Point
You can write a raw value to a data point. To do this, you must include a LonFormat attribute and set
it to "RAW_HEX".
<UCPTvalue LonFormat="RAW_HEX">10</UCPTvalue>
4.3.5.4 Writing Values to Structured Data Points
You can write to the individual fields of structured data points. To do this, you must include a
LonFormat attribute and set it to the field of the specific data type using the following format:
datatype.field. For example, to write to the setting field of a SNVT_scene data point, you would set
the LonFormat attribute to “SNVT_scene.setting” and then specify the value to be written to the field.