Tuning policies configure how a network evaluates write requests (for example, requests to write to writable proxy points) and the acceptable freshness of read requests. They associate with one of three poll rates in a network’s Poll Service.
The BACnet driver is unique among drivers in that it supports multiple communication port types: Ip port, Ethernet port, Secure Connect port, and MS/TP port. All port types can coexist under one network-level component (BacnetNetwork). The driver uses a separate BacnetMultiPoll (Poll Service) under for each port.
A multi-thread capability exists in all BACnet poll services where point polling might involve a BACnet router (say, going between B/IP and slower MS/TP devices). This capability is sometimes needed even in a (typically speedy) Ip port or Ethernet port link layer.
Unique to BACnet polling is the interplay with BACnet COV services, where some server devices may offer COV for point updates—a desirable alternative to polling. This affects tuning policy configurations, and how you should assign tuning policies for points.
By default, any BACnet proxy point polls support only one configured polling property. Thus, if you specify presentValue, which displays all of a point’s out values, no native object status or currently-active level (bac=n (if a commandable object) affects the point display. However, as needed you can add either or both of these extra polled properties, and/or others, by editing the facets of your proxy points.
For devices that support COV, the driver offers client support for BACnet COV services, which receive notifications when proxy point data change.