Echelon SmartServer 2.2 - Manual (Page 433)

434 Scheduling
for the data point and override the other application.

If a Locked icon ( ) appears to the left of the data point, a “Priority
too low to set value” error has occurred. You need to click the button to
the right and enter a higher priority in the Edit Value dialog for the
View – Data Points Web page to write to the data point.

If an unplugged icon ( ) appears above the data point, the data point is
offline.

If a yellow alarm bell icon ( ) or a red alarm bell icon ( ) appears to
the left of the data point, the data point is an alarm condition.

If a warning symbol appears ( ) to the left of the data point, the data
point has a configuration error.
Unit Displays the unit string of a scalar data point or the unit string of the selected
field of a structured data point. This field is read-only.
For example, the unit string for an SNVT_temp_f#US data point, which is
scalar, is “degrees F”. A SNVT_switch data point, which is a structured,
has “% of full level” and “state code” unit strings describing its state and
value fields. The unit string displayed for a structured data point depends on
the field selected in the Format list.
Multiple data point values will only be scaled properly in the trend graph if
they have the same unit string. You can edit the unit string of a data point in
the Configure – Data Point Web page, which you can access by clicking
General and then clicking the data point in the navigation pane.
Priority Displays the priority the View - Data Points Web page has for writing
updated values to the data point. This value may range from 0 to 255
(highest to lowest priority). By default, this property displays the priority
currently assigned to the data point. This is the priority used by the last
object or application that updated the data point. For example, if a
Scheduler with a priority of 220 updated the data point last, the data point’s
priority is 220.
You can assign the View - Data Points Web page a priority for writing
updated values to a data point by clicking the button to the right in the
Values box, which opens the Edit Value dialog. In the Priority box to the
right of the data point name, enter the priority for the View - Data Points
Web page to use in order to write to the data point and then click OK.
The priority you specify must be equal to or higher than the priority used by
the last application that updated the data point. Similarly, if you update the
data point with this Web page, the next application must specify a priority
equal to or higher than the one you specified in order to write to the data
point. If you set a priority that is less than priority used by the last
application that updated the data point, an error message opens stating that
the priority level you set it to low and that you can click the green hand icon
in the View - Data Points Web page to reset the data point priority.
You can reset the priority of a data point by clicking the green hand manual
override icon
( )
in the View - Data Points Web page. This sets the data
point's priority to 255 and notifies all other objects and applications in which
the subject data point is registered. The next highest priority application or
object will then assume the priority for writing values to the data point. For
example, if a Scheduler is currently active and has the highest priority for
writing to the data point at 220, the data point priority is set to 220.