Annex B (informative): BACnet Client Implementation

B.1 General

This annex is an informative best practice description of the behaviour of the BACnetUaMapper that implements this mapping document as an OPC UA server and BACnet client.

B.2 BACnet revisions

The minimum revision support required for the BACnetUaMapper is revision 7. The BACnetUaMapper should be prepared to communicate with BACnet servers supporting BACnet revision 4 or higher.

B.3 Timestamps and time synchronization

BACnet devices use local time for timestamps. OPC UA uses UTC time for timestamps. BACnetUaMapper should provide configuration options to handle the local time to UTC time conversion in the right way.

B.4 List handling

The methods defined in this specification for modification of BACnet list properties should be mapped to BACnet services AddListElement and RemoveListElement.

BACnet servers may not support the BACnet services AddListElement and RemoveListElement. An alternative method to update BACnet list elements could be:
Reading the entire list,
modify the content with the changes and
write back the list to the property.

B.5 Write with priority

The BACnetUaMapper should have a configuration option for the default priority used when a BACnet property is written through the OPC UA server. The default value for this configuration option should be the BACnet priority 8 which is “Manual Operator”.

B.6 Confirmation of confirmed event notifications

The BACnetUaMapper should automatically confirm (SimpleACK) the receipt of a confirmed event notification.