ASHRAE 135-2020

Meet Building Automation and ControlSystems Communication Needs with Standard 135-2020
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BACnet, the ASHRAE buildingautomation and control networking protocol, has been designed specifically tomeet the communication needs of building automation and control systems forapplications such as heating, ventilating, and air-conditioning control; fireand other life safety and security systems; energy management; lightingcontrol; physical access control; and elevator monitoring systems. The BACnetprotocol provides mechanisms by which computerized equipment of arbitraryfunction may exchange information, regardless of the particular buildingservice it performs. As a result, the BACnet protocol may be used by mobile andcloud-hosted devices, head-end computers, general-purpose direct digitalcontrollers, and application-specific or unitary controllers with equal effect.

This protocol provides acomprehensive set of messages for conveying encoded building automation databetween devices:
* Hardware binary input and output values
* Hardware analog input and output values
* Software data values
* Schedule information
* Alarm and event information
* Trend and event logs
* Files
* Control logic
* Application specific data for a large range of building services
* Network configuration including security

The 2020 edition of Standard 135 includesmany new capabilities and several clarifications. New capabilities include lightingand elevator device profiles that provide a standardized description for thesetypes of devices, along with audit reporting and logging to capture auditableactions. BACnet Secure Connect, a BACnet datalink layer, was also added. Thisdatalink is fully compatible with all existing BACnet datalinks and provides aninteroperable secure path for BACnet communications.