ASHRAE 135:2012

This protocol provides a comprehensive set of messages for conveying encoded binary, analog, and alphanumeric data between devices including: (a) hardware binary input and output values, (b) hardware analog input and output values, (c) software binary and analog values, (d) text string values, (e) schedule information, (f) alarm and event information, (g) files, and (h) control logic. This protocol models each building automation and control computer as a collection of data structures called objects, the properties of which represent various aspects of the hardware, software, and operation of the device. These objects provide a means of identifying and accessing information without requiring knowledge of the details of the device's internal design or configuration.