Solution:

BACnet is a communications protocol which was designed to allow communication of building automation and control systems for applications such as heating, ventilating, and air-conditioning control (HVAC), lighting control, access control, and fire detection systems and their associated equipment. The BACnet protocol provides mechanisms for computerized building automation devices to exchange information, regardless of the particular building service they perform. The BACnet protocol defines a number of services that are used to communicate between building devices. The following table list out the part of object access services. BACnet devices are not required to implement every single Service. Just one Service, ReadProperty, is required to be processed by all BACnet devices. Normally, no matter polling multiple data or single data, due to the default configuration, WebAccess both uses ReadPropertyMultiple service to reduce bandwidth usage, but some BACnet slave device may not support ReadPropertyMultiple service. This SOP will show you how to make WebAccess SCADA BACnet driver poll a data by ReadProperty service.