Glossary of LonWorks Terminology

Bridge
A bridge simply forwards all messages that match the domains between the two channels connected to the bridge.

Channel or Segment
A channel or segment is the transmission media that connect devices on the network such as twisted pair 78 kbps or power line carrier.

Device
A device or node is the piece of equipment installed on the network such as a sensor, actuator; or controller.

Domain
A domain is a logical grouping of devices that can communicate with each other over shared resources such as transmission media. Each network must have at least one domain. A domain is identified by a domain ID that can be 0,1,3, or 6 bytes. Larger domain IDs increase network overhead since the domain ID is sent with every message packet.

Groups
A group is a logical collection of nodes within a domain. A group can contain up to 64 nodes. A single domain can contain up to 256 groups.

Location
Locations are convenient subdivisions of a network that contain related sets of application devices and routers. Locations may correspond to physical places. Each network must have at least one location.

Network Variable
A network variable is an object on one node that can be connected to network variables on one or more additional nodes. A node’s network variables define its inputs and outputs from a network point of view and allow the sharing of data in a distributed application.

Node
A node is synonymous with device. It may have up to 255 network variables defined. Simple nodes may have up to 62 variables defined.

Repeater
A repeater forwards all messages between the two channels connected to the repeater.

Router
A router connects one segment of a channel to another segment of a channel or two different channels such as twisted pair and power line communications. A configured router sends only messages destined for nodes that are specified in the internal routing table created by a network management tool. A learning router monitors network traffic and learns the network topology at the domain/subnet level. The learning router then uses its knowledge to selectively route packets between channels.

Subnet
A subnet is a logical collection of up to 127 nodes or devices within a domain.

Standard Network Variable (SNVT)
Pronounced “snivet”, SNVTs are a set of predefined types of network variables with associated units, such as degrees centigrade, volts, or meters. SNVTs promote interoperability of products from different manufacturers by standardizing the names given to output and input network variables.

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