scope:

ClimateTalk is an open standard that defines a set of messages and commands to enable interoperability, enhanced user interface, and machine-to-machine control independent of the physical layer connecting the devices.

The messages and commands defined by the ClimateTalk Information Model (CIM) are the presentation and application layers as defined by the OSI Model.¹ ClimateTalk Applications are fully defined at Layer 7 of the OSI Model by a combination of a Device Specific Application Profile, the Generic Application Specification, and the Command Reference.

ClimateTalk messages can be carried over any physical medium following the OSI model. The ClimateTalk Presentation Layer defines how messages are executed over the various physical mediums in use.

CT-485 and CT-LWP are wired serial physical and network layers designed to support the formation of ClimateTalk networks and transport ClimateTalk messages, but other OSI-based protocols-including wireless transports-can be used as well.

This document defines the specific application requirements for an HVAC subsystem designed to ClimateTalk Open Standards. This profile defines how HVAC subsystem components control, operate, and monitor an HVAC system on a ClimateTalk network. This document defines the interaction and distribution of control and data among a thermostat, an indoor unit (furnace or air handler), and an outdoor unit (air conditioner or heat pump). This profile builds on the Generic Application Specification defining requirements common to all ClimateTalk enabled devices.

The ClimateTalk Open Standards package shown in Figure 1 prescribes the mandatory requirements to ensure proper network formation of interoperable devices. Membership in the ClimateTalk Alliance as well as successful completion of mandatory conformance testing is required for listing a product as a ClimateTalk Certified Device.

This profile also defines the testable requirements used to validate that the devices in an HVAC subsystem are behaving properly within a ClimateTalk network. Each device must comply with the mandatory requirements defined in this document as well as all other ClimateTalk standards applicable to the device functionality.