By default, the “Discovered” table for Bacnet objects lists the single BACnet Device object at top, and other objects underneath, with each object initially occupying a single row. See Figure 28.
You can resort objects by clicking on any column header. Often, this is useful to sort by “Object ID” (BACnet object type), to group like type objects together.
Also, you can click to expand any object (Figure 29). This lets you select other properties (apart from Present_Value) as a candidate to proxy.
The following sections provide more details about the Discovered pane in the Bacnet Point Manager:
By default, the following columns appear in the Discovered table, from left-to-right:
Object Name Object ID Property ID Index Value Description
The Object_Name property of the discovered BACnet object. This name should be unique within this specific device. When you select an object to add as a proxy point, this is the default (Niagara) name in the station for the Bacnet proxy point.
If BACnet objects in the device are organized in some hierarchical folder scheme, the Object Name reflects this, using a forward slash (“/”) between folders. For example:
J4_R2c/BNetServer/Dev_20/BFan_BO_20
The Object_Identifier property of the discovered BACnet object, which is a combination of BACnet object type and instance number (unique within that type). In this column, these two fields appear separated by a “:”, using Niagara descriptors for type. For example:
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analogInput:3
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multiStateValue:3
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binaryOutput:3
The property shown for the discovered BACnet object. By default, all objects that have a Present_Value property are listed with this value “on top,” as shown in Figure 28. BACnet objects without a Present_Value property (for example, a Device object or Trend Log object), list showing another property as the top Property ID.
Typically, present value is the most useful piece of data from any BACnet object. However, you can expand any discovered object (Figure 29) to see all its other properties as children in the discovered pane, where each one is a separate proxy point candidate. Additionally, properties that are “arrays” are further expandable (see Index column).
This is a numeric index into an “arrayed” property, if selected, otherwise is blank. For example, if you expand a “priority-type” object (e.g: object type “binaryOutput”) and expand again on its “priorityArray” property, each child row displays with a unique index number (1—16).
Use this to proxy a point to write to only one specific level of the “Priority_Array” property of the target BACnet object (instead of accessing all levels, by proxy of
only the default “presentValue” property). This may be useful in your control scheme, if you have a number of possible sources
in the station you wish to evaluate (on a Niagara priority basis), to write to one BACnet priority level (only) in the target BACnet object.
The (static) value of the associated property, captured when Niagara retrieved the object list (or, for any “non-default” properties, when you expanded the “top” property—see Property ID).
Discovered values display showing any descriptors associated with the BACnet object’s related properties (Units, Active_Text, Inactive_Text, and so on).
You can rerun a point discover as many times as needed. If the BACnet device contains many objects, you may wish to add multiple BacnetPointFolders (using button), and add discovered points differently into each one, using the Bacnet Point Manager view available with each folder.