BacnetPoll is used to configure and manage a group of Bacnet proxy points to be polled. The BacnetPoll provides a flexible polling algorthim based on four “buckets.”

Each pollable proxy point assigned to a BacnetPoll is configured in one of three buckets: fast, normal, or slow. In addition there is a fourth bucket called the “dibs stack.” Whenever a point is subscribed it immediately gets “first dibs” and goes on the top of the dibs stack. The poll scheduler always polls the dibs before doing anything else. The dibs stack is polled last-in, first-out (LIFO). As long as entries are in the dibs stack they are polled as fast as possible with no artificial delays.

When the dibs stack is empty the scheduler attempts to poll the components in each bucket using an algorthim designed to create uniform network traffic. For example if the fast rate is configured to 5000ms and there are 5 components currently subscribed in the fast bucket, then the scheduler will attempt to poll each component with a second to delay.

Every ten seconds the poll scheduler rechecks the buckets for configuration changes. So if a point’s configuration is changed from slow to fast, it takes at most ten seconds for the change to take effect. Statistics are also updated every ten seconds. Statistics may be manually reset using the resetStatistics action.

For additional details, see “About poll components” in the Drivers Guide.