HART® COMMUNICATION FOUNDATION Document Number: HCF_SPEC-54 HART® FSK PHYSICAL LAYER SPECIFICATION Preface This preface is included for informational purposes. This revision 8.0 of the HART FSK Physical Layer Specification has evolved from the previous released revisions 7.0, 7.1, and 7.2. and from the document Voltage Modulation Physical Layer Specification, Revision 1.0 (HCF_SPEC-70), which is superceded. Revision 8.0 which differs from the previous revisions the following ways: Device Names: Device names are no longer referred to by their ‘Data Link Layer’ names. New names for devices were created to represent their unique electrical properties. Devices Types: This revisions allows more device types to exist within a HART network. Device Topologies: This revision allows for new HART network topologies to exist, supporting new device types. Document Format: The document was reformatted to align itself with IEC/ISO directives. This standard was developed by the HART Communication Foundation Physical Layer Working Group. The intent of this specification is to define the electrical properties of HART devices and networks, to facilitate the design of related products. The following people actively served as members of the HART Physical Layer Working Group in the creation of this specification: