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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 (A - C)

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



Acknowledged Service

A service of the LonTalkĀ® protocol ensuring a message was received by the addressees. After a configurable number of retries, failures are logged in a status register in the node that can be accessed by network-management tools.


Any component that affects a physical variable of the system under control or indicates the values of system variables for human operators.  Some examples are pumps, fans, heaters, alarm annunciators, and operator displays.  This term may apply only to the component that converts electrical or pneumatic control signals into a physical force that causes a mechanical component, such as a damper or valve, to move; or it may apply to both components as a unit.

Ad Hoc Configuration Scenario

A tool is used to design and install the network on-site while it loads the network configuration information into each device as the device is defined and configured and connections are created.  The network database is built simultaneously.  This is different from the Engineered System Scenario in that information is incrementally loaded to the physical devices.  This scenario has the advantage of offering the most flexibility by letting the installer make decisions on-site.  It is most appropriate for simpler systems in which the details of the system to be installed are not known prior to commissioning. See also Engineered System Scenario.

Address Table

A table on a Neuron Chip that is limited to 15 entries and defines the groups to which the LonWorks Device belongs and the destinations to which it sends bound network variables and explicit messages. The address table entry also contains information such as the transport properties; i.e., retry count, timer values, etc.

Since the output network variable refers to the address table when it sends a message, multiple network variables can share an address table entry if both network variables are bound to the same target device(s) and the transport properties are the same.

When a downstream device’s network variable polls an upstream device for its value, the downstream device is the initiator of the update, therefore it needs to know where the information is coming from and it must use an address table entry.

The contents of the address table are filled-in by the NSS when it creates connections.


A network variable alias is a copy of a network variable containing the same value as the primary network variable but using a different selector.  Since it has a selector that is unique, it allows for complex connections to be created.

Application Program / Application

Every device must contain an application. The application may be in a device when it’s purchased or it may be loaded into the device from application files (.APB and .NXE extensions) using a network-management tool.  The application determines how a device functions.

The software code in a LonWorks device that implements the “personality” of the device.  Also referred to as the application or the application layer, it resides in ROM or is downloaded over the network into non-volatile RAM.  The application program interfaces with the LonTalk firmware to communicate over the network.  It may reside completely in the Neuron Chip, or it may be split between the Neuron and an attached host processor (a host-based device).

Application Configuration

A process by which the application program in each node is tailored to the desired functionality by selecting the appropriate configuration parameters.  LonWorks Network Services (LNS®) provides a platform for manufacturers to create easy-to-use graphical configuration interfaces, called plug-ins, that are then automatically compatible with any other LNS-based network tool.

Application Device

An application device is a LonWorks device that runs a LonTalk layer-7 application.  The layer-7 application may run on a Neuron Chip, in which case the device is called a Neuron Chip-hosted device.  The layer-7 application may run on another processor, in which case the device is called a host-based device Neuron Chip application programs are developed with the LonBuilder Developer's Workbench or the NodeBuilder tool and then exported to the application device.  Some Application Devices use a Neuron Chip as a network interface, and execute their application programs on a host processor.  In this case, the Neuron Chip in the network interface executes the LonBuilder Microprocessor Interface Program (MIP) to communicate with a LonWorks network as well as the host processor.

Applicationless Device

A device state where the device has no application image.  Program or hardware failure may also cause a device to become applicationless.


A service provided by the LonTalk protocol used to ensure that a received message was sent by an authorized source.

Backbone Network

A high-speed network channel connecting several lower speed channels.


A specification for a protocol created by ASHRAE and used by some manufacturers to gain a degree of upper-level interoperability.


Binding is a process that takes place during network design and installation. The device firmware is configured to know the logical address of the other devices or group of devices in the network expecting that network variable, and it assembles and sends the appropriate packets to these devices. Similarly, when the device firmware receives an updated value for an input network variable required by its application program, it passes the data to the application program. The binding process thus creates logical connections between an output network variable in one device and an input network variable in another device or group of devices. Connections may be thought of as “virtual wires”.

The process that defines connections between LonWorks Devices. Connections define the data that devices share with one another. 

Bit Rate

The rate in bits at which the packet frame is transferred across the communication medium.

Bound Monitoring

Creates an event-driven update connection between the network variable being monitored and the browser.  Therefore the browser will report a change in network variable value as the value changes.  To turn on bound updates, right-click a network variable in the browser and select Properties.  Open the Monitoring tab and select Bind this network variable to the browser for receiving network variable updates Bound monitoring can also be accomplished by binding network variables to the local network service device's virtual functional blockSee also Polling.

Communications Channel

The communications media that connect LonWorks devices or the path between devices that exhibits various physical characteristics.  Different transceivers may be able to interoperate on the same channel. Segments connected via a physical layer repeater are considered a single channel.  LonWorks Routers are used to connect two channels.

Channel Segment

A portion of a channel.  A single channel can be comprised of multiple segments connected by physical-layer repeaters.

Channel Type

Channels are categorized by channel type, and every type of transceiver must identify the channel type or types that it supports.  The choice of channel type affects transmission speed and distance as well as the network topology.


A task that is requesting service from a server. See also Remote Client.

Client ID

A unique identifier assigned to a client when the client is created.  The NSS uses client IDs to track the source of each service invocation.

Client-Server Architecture

An architecture where a device (client) makes a request to another device or object (server) that delivers it.

Commissioning a Device

The process of using a network-installation tool to download the network-configuration data and application-configuration data to a device.  For devices whose application programs are not contained in ROM, the network tool also downloads the application program into non-volatile RAM memory in the device.  Devices are usually either commissioned and tested one-at-a-time or commissioned in off-line mode then brought on-line and tested one-at-a-time.

Communication Protocol

Rules and procedures governing transfer of information between devices on a network.  The abbreviated term protocol is often used.  The protocol defines the format of the message being transmitted between devices and defines the actions expected when one device sends a message to another.  The protocol normally takes the form of embedded software or firmware code in each device on the network.  The LonTalk protocol is defined in the USA by the ANSI/CEA 709-1 standard, defined in the European Union by the EN 14908-1 standard, and defined in China by the GB/Z 20177.1 standard.

Configuration Network Variable

A special class of network variable used to store network-modifiable application-configuration data.  Configuration network variables are always inputs.  For Neuron Chip-hosted Application Devices, the contents of configuration network variables can be stored in the device's on-chip EEPROM, or off-chip EEPROM, Flash , or NVRAM.  For host applications, it is the responsibility of the host to store configuration values.

Configuration Properties

Applications may contain network variables and configuration properties. These are defined in the device template Configuration properties are data structures specified by the LonMark Guidelines that provide standards for documentation and for the network message formats used to download the customization data to the device by network tools.  Configuration properties within a device are set during installation, operation, and maintenance to determine how the data are manipulated within the device.  The application reads the values from the network variables and configuration properties and performs functions upon them.  For example, an application may allow an arithmetic function (add, subtract, multiply, or divide) to be performed on two values received from two network variables.  The function to be performed could be determined by a configuration property.

Configuration properties are used to configure the operation of a device, a LonMark function block within a device, or the behavior of a network variable within the LonMark function block Configuration properties may be implemented using a special class of network variable called a configuration network variable, or they may be implemented as configuration parameters stored in a data block that is read and written using the LonWorks File Transfer Protocol (LW-FTP) or Direct Memory-Read/Write (DM-R/W).

Configured Device

A device state where the device has both an application image and a network image.  This indicates that the device is ready for network operation.


The implicit addressing established during binding.  A connection links one or more logical outputs (network variables or message tags) to one or more logical inputs.

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