BacnetDevice properties

When you add (or edit) a BacnetDevice from the Bacnet Device Manager, several key device properties appear in that dialog, as shown in Figure 32.

Figure 32. Add dialog in Bacnet Device Manager

These properties are described as follows:

Name

As learned, this reflects the “Object_Name” property from the device’s sole Device object.
Each slash (“/”) character (if any) is replaced by a period (“.”) in the Niagara name.

This is only the Niagara component name for this device—if desired, you can edit it to whatever you want. It does not affect the name in the remote BACnet device.
Type

Type is specific type of BacnetDevice. Typically, is single selection only of Bacnet Device.
Device ID

The BACnet Object_Identifier reported (if learned) by this device. Editing does not affect the device’s ID, only the ID used by Niagara to access this device.
MAC Addr

The data link layer MAC address for this device. If a B/IP device, this is IPaddress:UDPport, similar as shown in Figure 32. If an MS/TP device, this is an 8-bit address (0-254) that is unique on its RS485 trunk.
Enabled

A flag indicating whether Niagara has enabled communications to the device.
Use Cov

A flag specifying whether Niagara attempts to subscribe for COV notifications, as a way to monitor proxy point values.
- If the device was learned, and Niagara determined that the device indicates support for server-side COV, this flag defaults to true.
- Otherwise, this flag is false. In this case, no proxy points under the device will use COV.
If true, then individual proxy points under the device may use COV subscriptions, depending on their assigned tuning policy. See Bacnet Tuning Policy notes and Client COV notes.
Max Cov Subscriptions

(Applies only if “Use Cov” is true.) Specifies the maximum number of COV subscriptions that Niagara will attempt to use with this device. This allows the station to restrict itself from consuming all of the available subscription space in that device.

Notes on other BacnetDevice properties

In addition to properties shown in the Add or Edit dialog from the Bacnet Device Manager, a BacnetDevice has a few other properties, as shown in Figure 33.

Figure 33. Additional BacnetDevice properties

Typically inconsequential, these other BacnetDevice properties are as follows:

Enumeration List

An expandable list of extensible BACnet enumerations that are defined and applicable for this specific device. In rare cases, adding or editing items in this list may provide utility for proprietary data items in the BACnet device—perhaps property IDs.
Cov Subscriptions

(Read Only) Number of active COV client subscriptions to this device.
Character Set

(Read Only) The character set encoding used by this BACnet device, e.g. ANSI X3.4 (Ansi X3_4).

Starting in AX-3.7u1, another possible slot has importance. See BacnetDevice "skipUpload" slot.

BacnetDevice "skipUpload" slot

Upon station startup, the BACnet driver has always automatically uploaded all “Device object” properties for each represented BACnet device, after which the station’s BacnetNetwork is fully initialized. Typically, such property uploads are inconsequential if there are mostly BACnet/IP or BACnet Ethernet devices.

However, if a BacnetNetwork that includes many MS/TP devices, this can cause a long delay at station startup. During all these Device object uploads, more critical point data reads and writes cannot occur.

Starting in AX-3.7u1, any BacnetDevice with a Boolean slot named “skipUpload” (with a value of true), skips this upload at station startup. Note at any time, you can still manually invoke the Upload action on any BacnetDevice to refresh these values—typically, most Device object properties have static values.

If necessary, you can manually add this slot and value by doing the following:

Go to the slot sheet of the BacnetDevice (typically, one for an MS/TP device).
Add a slot with Name: skipUpload and choose Type: baja, Boolean
Go to the property sheet of the BacnetDevice and set the value of this new property to: true
Save these changes.

Alternatively, you can use the Batch Editor of the station’s ProgramService to do all the above on multiple selected BacnetDevices. For related information, see the NiagaraAX Batch Editor engineering notes document.

Starting in AX-3.8, the BacnetNetwork has new “uploadOnStartup” property, which you can set from false (default) to true in order to have child BacnetDevices (from that point on) to be automatically created with the “skipUpload” slot, with a value of true. In this case, note that the added skipUpload slot on BacnetDevices is hidden. For related details, see BacnetNetwork "uploadOnStart" property.

When engineering a BacnetNetwork with mostly MS/TP devices in AX-3.8, a possible tactic is to set the network-level “uploadOnStart” property to false before adding BacnetDevices. Then if desired, you could go to the slot sheet of BacnetDevices for B/IP and/or B/Ethernet devices and either delete (or unhide to change from the property sheet) the hidden “skipUpload” slot.