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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 (G - I)

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



Gateway Device

A LonWorks device that allows proprietary legacy control systems to be interfaced to LonWorks systems. A gateway device has a physical interface appropriate to the foreign system device or communication bus.  Its application program interfaces to the proprietary communication protocol for the foreign system, translates between the two protocols as required, and converts the proprietary command-based messages of the foreign system to SNVTs used by the information-based LonWorks applications.

Graphical User Interface (GUI)    (See Human-Machine Interface)



A logical collection of devices within a domain.  Unlike a subnet, devices are grouped together without regard for their physical location in the domain.  The number of groups to which a device may belong is determined by the number of available address table entries on it.  This number is set by the Neuron application, but may not exceed 15.  Groups and group membership are defined by the NSS during binding.

Group Addressing

A logical addressing mode in the LonTalk® protocol that allows a message to be sent simultaneously to a pre-configured group of devices. Each group has an 8-bit group ID. Each domain can have up to 256 groups defined.

Group ID

A number used to identify a group. Each group is assigned a unique ID from 0 to 255 by the NSS.

Group Member Number

Within groups that use acknowledged message service, each member of the group is assigned a group member number. Devices use their member number to determine if reminder messages indicate that their acknowledgment or response was already received.

HMI (See Human-Machine Interface)



A device implementing layer 7 of the LonTalk protocol.  A host may be based on the Neuron Chip, in which case it is called a Neuron Chip Hosted Device.  A host may be based on another processor, in which case it is called a host-based device.  A host-based device uses the Neuron Chip as a network interface to talk to the LonWorks network. 

Host-Based Device

A devices in which layer 7 of the LonTalk protocol runs on a processor other than the Neuron Chip.

Host Network Variables

A variable managed by the computer that contains the LNS Network Interface. Bound updates to host NVs allow the computer to collect network data with greater efficiency than polling.

Host Processor

The application processor for a host-based device; typically a micro-controller, microprocessor, or computer.


The center of a connection, specified by node handle and network variable index or message tag index. Each connection is defined in terms of a hub and a set of items that connect to the hub. The hub must be either the only input or the only output in the connection. For example, if the hub is an output network variable, all the other members in the connection must be input network variables.

Human-Machine Interface (HMI)

Also commonly a Graphical User Interface (GU), is primarily used for monitoring, control and interaction with the control network. Functions such as monitoring, control, scheduling, alarming, and trending are primary usages.

Implicit Addressing

A form of messaging in which the Neuron Chip firmware builds and sends network variable update and explicit messages using information contained in tables in its EEPROM. Implicit addressing is established during binding.

I/O Interface

An electrical interface from a LonWorks device – such as voltage, current, or contact closure – to a non- LonWorks sensor or actuator. The I/O interface can be digital (on/off), analog, or a communication protocol.

Infrastructure Devices

Generally includes the devices of the Infrastructure Subsystem, i.e. routers, repeaters, terminators, power supplies and the LNS® Network Interface.

Infrastructure Subsystem

The top-level subsystem that is the central place for managing routers, other subsystems, channels and the LNS Network Interface.

Input Network Variable

A network variable that provides information to the device from some other devices on the network.


A condition that ensures that multiple devices (from the same or different manufacturers) can be integrated into a single network without requiring custom device or tool development.

There are a number of benefits to using interoperable devices:

  • Project engineers can use the best-of-breed systems
  • Interoperable products give manufacturers a chance to compete in systems that would otherwise be closed
  • Engineering teams can build to a standard specification
  • Building, Factory and Plant managers can monitor values using standard tools regardless of the company that manufactured the devices.

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