Technical Resources

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  Related Information

Device Certification - LonMark conformance instructions.

Design Guidelines - Technical information for developing open interoperable LonMark products.

Technical Corner - Provides answers to commonly asked technical questions.

LonMark Members who manufacture products used in Open Systems

Terminology (M - N)

The descriptions and terminology contained within this document are made in the context of use with LonWorks® networks and products.



Media  (see Physical Medium)



A LonWorks network uses a networking protocol, LonTalk®, to communicate among devices. Therefore, it doesn't care whether the media is twisted pair, power line, fiber, or any other type of physical connection among the network's nodes. In fact, the media can be mixed and matched depending on what saves money or the physical constraints of the installation, therefore the network is said to be media independent.

Message Code

A 1-byte field in a LonTalk message that identifies the type of message. The following table lists the message types supported by the LonTalk protocol and the message codes used for each type, ex. Application Message, Foreign Frame Message, etc.

Message Service Types

The three main types of messaging services are Acknowledged, Unacknowledged, or Repeated messaging. The browser can also be set to use Priority Messaging and, if so, the priority slot that will be used. When using acknowledged or repeated messaging, the user can specify the number of times the browser sends a message. Unacknowledged messaging sends a message one time. The default message service type depends on the device manufacturer, but it is typically acknowledged.

Message Tag

Logical input and output ports that nodes use to send and receive explicit messages. A node always contains a msg_in tag and may contain declared message tags as well. Declared message tags are bi-directional (the node can both send and receive messages with them). The msg_in message tag can only be used to receive messages.

Generally nodes use network variables to communicate with one another since they are interoperable and produce more efficient code.

Message Tag Index

A number used to identify a message tag. Message tag indices are assigned by the Neuron C compiler in the order in which the variables are declared. The first message tag in a program is index 0, the second is index 1, and so on.


An acronym for Man-Machine Interface, which has been, replaced with the acronym HMI or Human-Machine Interface.

Monitor Sets

Groups of monitor points that the network management tool uses to monitor and control network variables.

Network Address

A device's logical (domain/subnet/node) address. This address is assigned at installation time by the NSS.

Network Configuration

The process of converting a network design into the data elements required by the LonTalk protocol in each node of the network. This includes:

  • Assigning domain ID and logical addresses to all devices and groups of devices.
  • Binding network variables to create logical connections between devices.
  • Configuring the various LonTalk protocol parameters in each node for the desired features and performance, including channel bit rate, acknowledgement, authentication, priority service, etc.
Network Configuration Tool

Software applications which are used to facilitate the network configuration process. Functional network design is as simple as dragging the devices’ application functional blocks onto the drawing and connecting inputs and outputs to determine which functional blocks use what network variables.

Network Database

A database used by a network installation tool to allocate and track network resources. The installation tool uses the network database to ensure that resources are allocated correctly and efficiently and so that damaged devices can always be replaced. The network database can also be used by user interface applications to ensure that the user interface names match the installed devices.

Network Driver

Software that runs on the host that manages the interface with the NSI or network interface. This driver isolates the host application from the hardware and software implementation of the interface.

Network Image

A device's network address and connection information.  For Neuron® Chip hosted devices, the node's network image is stored in EEPROM on the Neuron Chip.  For host applications, all of the network image except the network variable configuration table is stored in EEPROM on the Neuron Chip.

Network Interface Device

Referred to as the Network Adapter and formerly known as a Network Services Interface [NSI]. It is a LonWorks device that has a physical interface to an external host computer such as a PC or a hand-held maintenance tool. The device application program provides communication protocols and an API (application programming interface) to allow host-based applications such as network tools to access the LonWorks network. For optimum performance when attached to LonWorks networks, use an LNS® Fast Network Interface (also known as a VNI).

Network Management

The management of functions, services, events, and properties in an integrated LonWorks network.

Network Management Tool

A software application which is used to facilitate one or more network management tasks, such as network design, configuration, installation, documentation, maintenance, modification, monitoring, or supervisory control.

Network Merge

Initially a network can be installed as a number of independent sub-networks, each with an independent LNS Server, and later the sub-networks can be merged into one network.

When multiple systems are being installed, the installers for each system want to install and debug their installation without interference from other systems.  When each system has been correctly installed, they can be merged into a single network.

Network Recovery

The recovery process uses the Database Recovery Wizard to create a network design and the LNS database from an existing physical network. This feature is useful to create a network design if a backup copy does not exist or is unusable. The wizard retrieves as much information as possible from the network devices, given a network domain ID and, optionally, a database description file, and builds a complete LNS database. Even though it can rebuild the entire network database, database recovery is not a replacement for backing up a network database.

Network Services Interface (NSI)

The component in Echelon Corporation's LNS architecture that provides the physical connection to the LonWorks network, manages transactions with the NSS, and provides transparent remote access to the NSS.

Network Services Server (NSS)

The component in Echelon Corporation's LNS architecture that processes network services, maintains the network database, and enables and coordinates multiple points of access.  Note that the NSS-10 module combines elements of both the NSI and NSS, but does not support multiple points of access.

Network Variable

Applications may contain network variables and configuration properties. These are defined in the device template. A network variable is any data item (temperature, a switch value, or an actuator position setting) that a particular device application program expects to get from other devices on the network (an input network variable) or expects to make available to other devices on the network (an output network variable). Network variables allow a device to send and receive data over the network to and from other devices.

Every network variable represents a path through which data may flow into or out of a device via the network. All network variables are defined as either input or output; this determines whether the network variable handles data going into or out of the device.

Every network variable and configuration property has a type, which determines data interpretation, i.e. the content and structure of the data. LonMark International defines Standard Configuration Property Types, or SCPTs (pronounce skip'-its), and Standard Network Variable Types, or SNVTs (pronounced sni'-vits), which contain many common data types. For example, SNVT_temp_f is a network variable type for network variables containing temperature as a floating-point number, and SCPT_location is a configuration property type for configuration properties containing the device location as a text string. See the LonMark Resource Files for descriptions of all SNVTs and SCPTs. Applications may use non-standard types called user network variable types (UNVTs) and user configuration property types (UCPTs). These types are defined in user resource files. Additional resource files may be provided by device manufacturers. See Echelon Corporation's LNS Resource File Catalog Utility User’s Guide and the LonMark Resource File Developer’s Guide in the LNS Utilities and LonMark Reference help file for additional information on using these files.

High-level objects that application devices use to communicate with one another.  The types, functions, and number of network variables in each node are determined by the application code within the device.  Network variables make it easy to develop networked control applications by eliminating all of the low-level and tedious work of building and sending downlink messages, and receiving and responding to uplink messages.

Network Variable Index

A number used to identify a network variable. Network variables indices are assigned by the Neuron C compiler in the order in which the variables are declared. The first network variable declared is index 0, the second index 1 and so on. The NSS uses the network variable index to refer to the network variables on a node. Neuron Chip hosted devices can declare a maximum of 62 network variables (indices 0 to 61). The NSS for Windows supports host-based devices with up to 4096 network variables (indices 0 to 4095). The NSS-10 module supports host-based nodes with up to 255 network variables (indices 0 to 254). In an array of network variables, each element has a separate index.

Network Variable Selector

A 14 bit number used to identify connected network variables. Network variable selectors are assigned by the NSS during binding.

Network Variable Types

A network variable's type defines its structure and contents. A network variable type can be either a SNVT or a user-defined type.

Neuron Chip

A family of VLSI components that implements the LonTalk protocol.  The Neuron Chip is manufactured by multiple vendors and can manage I/O devices and execute user-written application code, or alternatively it can be used to create a network interface to a host processor.

Neuron Chip Firmware

Firmware required to operate a Neuron Chip and implement the LonTalk protocol. This firmware is contained in the VERxxx subdirectories of the LonWorks IMAGES directory (default C:\LONWORKS\IMAGES) in files with the name S*.NX*. A custom system image including the Neuron Chip firmware with extensions for the LTM-10 hardware is included in the LTMSYS.NX file in the VER122 subdirectory of the IMAGES directory. This file does not include the MIP image included in the LTM-10 module.

Neuron ID

The Neuron ID is a hardware address that will change if the hardware changes. Each LonWorks device has a unique 48 bit Neuron ID that was burnt into the Neuron chip when it was manufactured, resulting in approximately 300 trillion different combinations. The Neuron ID is broadcast through the network when a device is pinned so that a logical address (Subnet/Node ID) can be assigned. The network management tool must have the Neuron ID to commission a device. The Neuron ID does not contain information about the address of a device. A device’s Neuron ID and Subnet/Node ID can be found in the Identifiers tab of the device’s properties. See also Subnet/Node ID.


Another name for a network device / LonWorks device.  This term is used in the LonWorks Network Services Architecture.

Node Address

A unique 15-bit logical identifier for each node in a domain. The node address consists of two parts: a 7-bit subnet address and an 8-bit Node ID. The Node ID is unique within the subnet.

Node ID

The third part of the LonTalk addressing hierarchy of domain/subnet/node.  At installation time, each device is assigned a unique node ID within its subnet by the NSS.

Node Object

A LonMark functional block that monitors the status of all LonMark functional blocks in a device and makes the status information available for monitoring by network-management tools. It is responsible for disabling, overriding and testing the device.

NSI  (see Network Services Interface)


NSS  (see Network Services Server)


NV  (see Network Variable)



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