Regardless of NiagaraAX release level, the Bacnet driver is unique among all drivers in that there are multiple communication port types available (IpPort, EthernetPort, MstpPort), along with multiple instances of ports supported, all under one network-level component (BacnetNetwork). Thus, the driver design has always used a separate “BacnetMultiPoll” (Poll Service) component for each network port, where each “poll scheduler” component is found under BacnetComm, Network, <port>, as shown in Figure 10.

You can adjust the basic poll settings used for each port in its own poll scheduler, as well as see individual statistics. The basic operation of each Poll Service, including the four “buckets” (3 rate group + “dibs” stack) is explained in the Drivers Guide, in the section “About poll components”. Note that a “multi-thread” capability exists in all Bacnet Poll Services, as this is sometimes needed even in a (typically speedy) IpPort or EthernetPort link layer, where point polling might involve a BACnet router (say, going between B/IP and slower MS/TP devices).

Also unique to Bacnet polling (in any release) is the interplay with BACnet COV services, where some server devices may offer COV for point updates—typically, a desirable alternative to polling. This affects Tuning Policy configurations, and how you should assign tuning policies for points. For related details, see Bacnet Tuning Policy notes, BacnetDevice properties, and Bacnet ProxyExt properties.

And now for the release-level differences in Bacnet point polling: