Echelon OpenLDV - Manual (Page 18)

10 Using the OpenLDV API
Introduction to OpenLDV Programming
An application that uses the OpenLDV API is called an OpenLDV application.
The communications protocol used for OpenLDV applications is the ISO/IEC
14908-1 (ANSI/CEA 709.1-B and EN14908.1) Control Network Protocol. This
protocol is an international standard seven-layer protocol that has been
optimized for control applications, and is based on the Open Systems
Interconnection (OSI) Basic Reference Model (the OSI Model, ISO standard 7498-
1). The OSI Model describes computer network communications through the
seven abstract layers described in Table 2. The implementation of these layers
in a L ON W ORKS device provides standardized interconnectivity for devices within
a L ON W ORKS network.
Table 2. L ON W ORKS Network Protocol Layers
OSI Layer Purpose Services Provided
7 Application Application compatibility Network configuration, self-installation,
network diagnostics, file transfer,
application configuration, application
specification, alarms, data logging,
scheduling
6 Presentation Data interpretation Network variables, application messages,
foreign frame transmission
5 Session Control Request/response, authentication
4 Transport End-to-end
communication reliability
Acknowledged and unacknowledged
message delivery, common ordering,
duplicate detection
3 Network Destination addressing Unicast and multicast addressing,
routers
2 Data Link Media access and framing Framing, data encoding, CRC error
checking, predictive carrier sense
multiple access (CSMA), collision
avoidance, priority, collision detection
1 Physical Electrical interconnect Media-specific interfaces and modulation
schemes
Echelon’s implementation of the ISO/IEC 14908 Control Network Protocol is
called the LonTalk protocol. Echelon has implementations of the LonTalk
protocol in several product offerings, including the Neuron firmware, LNS
Server, SmartServers, and various network interfaces. This document refers to
the ISO/IEC 14908-1 Control Network Protocol as the “LonTalk protocol”,
although other interoperable implementations exist.
An OpenLDV application can work with Layer 2 network interfaces, Layer 5
network interfaces, or LonScanner Protocol Analyzer interfaces. Figure 3 shows