communications. ASHRAE initially created a method called “Annex H.3,”
allowing for the BACnet protocol to be “tunneled” through an IP network
(i.e., basically packaging the BACnet data into an IP message). However this
required each subnetwork to have a translator that could assemble and disas-
semble the data in the IP packet. The shortcoming of Annex H.3 was
addressed with Annex J BACnet/IP. BACnet/IP transmits BACnet messages
in native IP format, providing new flexibility and scalability to BACnet.
LonWorks
LonWorks is often referred to as a communications protocol for control net-
works, but because it bundles a communications protocol with a dedicated
microprocessor and media transceivers, it more closely resembles a networking
platform. LonWorks was created by the Echelon Corporation. In 1999, the
communications protocol (then known as LonTalk) was submitted and
accepted as a standard for control networking (ANSI/CEA-709.1-B).
In 2009, LonWorks became an international standard, ISO/IEC 14908.
Whereas LonTalk addresses the issue of how devices communicate, LonWorks
defines the content and structure of the information that is communicated.
The protocol is primarily focused on building and home automation, but is
also used in transportation and industrial automation.
The standard calls for two primary physical-layer signaling technologies;
twisted-pair cable and a power line carrier, although LonWorks can also use
radio frequency (RF), infrared (IR), coaxial cable and fiber optic cable. The
LonWorks platform uses an affiliated IP tunneling standard—ANSI/
CEA-852—in use by a number of manufacturers to connect the devices on
LonWorks-based networks to IP networks and applications. Many LonWorks
networks are deployed with some IP network integration.
LonWorks is primarily implemented using a device that contains an Echelon-
designed 8-bit processor, called the “Neuron chip.” Similar to BACnet objects,
LonWorks standardizes the functions and information of devices. Each stan-
dard is known as standard network variable types (SNVTs).
Modbus
Modbus is a communications protocol published by Modicon in 1979. At that
time Modbus primarily focused on communication to programmable logic
controllers (PLCs) manufactured by Modicon and used in industrial automa-
tion. Modicon is currently a company owned by Schneider Electric and in
2004 the Modbus standard was transferred to a nonprofit organization,
The Foundations of a Smart Building 23