Issue
The value of an exported Infinet point is not updated in some or all of the subscribing controllers.
Product Line
EcoStruxure Building Operation
Andover Continuum
Environment
Building Operation Automation Server
Continuum i2 Controller
Cause
The subscribing controller is offline or inaccessible when the IE update is broadcast.
Resolution
The main disadvantage with the Continuum Import/Export (IE) system is that, in certain cases, it is possible that the updated value may not reach one or more of the subscribers due to various reasons such as network or controller down problems, excessive traffic on the network etc.
This is not of big concern when the point is of an analog type that changes frequently such as a temperature input, since the point will update again when the temperature changes in a matter of seconds or minutes at the most. For binary values though, missing an update is a big concern.
Consider an occupancy schedule point that turns ON at 08:00 and off at 17:00. If a subscriber misses the 08:00 update the zones under control by the subscriber will be unoccupied the entire day.
The Point’s Refresh Attribute. Continuum points have a ‘Refresh’ attribute that is used to force the IE system to send a new updated value, setting the refresh attribute to true forces the Infinity controller to export the point’s value regardless of whether it has changed or not.
It is IMPERATIVE that a PE program periodically refreshes binary points that are exported in Infinity controllers such as i2 devices.
In the schedule example described above, a program can be added to the Infinet controller that hosts the exported point. This program should be triggered by the minute system variable and coded as follows:
This will ensure the any subscribers to the schedule OCC flag won’t go more than a minute with a stale value of the point.
Things to consider when refreshing exported points. a) Do not refresh points at a fast rate as this will cause unnecessary traffic on the Infinet field bus, refresh rates of one minute or more are strongly recommended.
b) For the same reason, when refreshing many points, the operation should be staggered to avoid flooding the Infinet bus with an avalanche of IE traffic at the same instant.
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