LONWORKS® Technology

The Neuron Chip


The Neuron Chip is the heart of the LONWORKS technology.

LONWORKS nodes usually contain a Neuron Chip to

  • process all LonTalk protocol messages
  • sense inputs
  • manipulate outputs
  • implement application-specific functions
  • store installation-specific parameters

The integral applications processor means that low cost nodes can be designed with as little as one VLSI device. The customer benefits from this technology because manufacturers are integrating it into their sensors and actuators to provide a wide variety of devices for use in networked applications. A stream of new products from a diverse group of manufacturers is now in development to take advantage of LONWORKS technology for present and future applications.


Each Neuron chip has three resident 8-bit processors: two processors dedicated to LonTalk protocol processing, and a third dedicated to the node’s application program. Neuron chips are manufactured under license by both Motorola and Toshiba, two of the four largest semiconductor manufacturers in the world.


Neuron chips are programmed in Neuron C, which extends ANSI Standard C to support an object-oriented approach to developing distributed applications. Neuron C provides direct support for LONWORKS objects such as network variables and SNVTs. The language also provides a new statement called the when statement that is used to schedule execution of user tasks based on predefined and user-defined events. In addition, Neuron C provides a syntax for declaring a wide range of I/O objects that are supported by the Neuron Chip application I/O hardware.

All services of Neuron C leverage the run-time support provided by the Neuron firmware. This firmware contains:

  • The LonTalk protocol communications software, including network management functions and network variable processing
  • An event driven scheduler
  • Run-time support for applications I/O objects
  • Arithmetic, logical, conversion and other application routine libraries

LONWORKS Transceivers

78 kbps Twisted Pair Transceiver - This transceiver allows you to build networks with distances up to 4600 feet or 1400 meters (worst case) in loop or backbone configurations. It provides transformer isolation between the node and network for high common mode noise rejection.

1.25 Mbps Twisted Pair Transceiver - This transceiver provides higher communications rates for distances up to 430 feet or 130 meters (worst case). It also provides transformer isolation between the node and network for high common mode noise rejection.

Power Line Transceivers - The power line can provide a good solution for network wiring in many applications. It eliminates the need to install additional wiring, significantly reducing installation costs. These transceivers communicates with either a proprietary spread spectrum or a narrow band technology that provides reliable communications for up to 2000 meters on a clear line. Transformers that inhibit transmission can be bridged with a simple passive circuit.

78 kbps Twisted Pair, Free Topology Transceiver - This transceiver allows you to build networks of nearly any configuration including bus, star, loop, and mixed configurations. It features low standby power and transformer isolation between the network and the node. Nodes with this transceiver can communicate up to 500 meters (1,600 feet) with no repeater and up to 1,000 meters (3200 feet) with one repeater.

Link Power Twisted Pair Transceiver - This transceiver provides the same communications capability as the free topology transceiver but adds distributed power capability to the network. Power is distributed over the network from a central power supply.

Radio Frequency Transceiver - A variety of RF transceivers are available for wireless communications in many different environments. Both licensed and non-licensed versions are available in the 400-470 MHz and 900 MHz bands respectively.

Kbp Peak Sustained Peak Sustained
4.88 25 20 7 5
9.766 45 35 13 10
19.531 110 85 25 20
39.063 225 180 50 40
78.125 400 320 100 80
156.25 625 500 200 160
312.5 700 560 340 270
625.0 700 560 500 470
1250.0 700 560 700 560

Capabilities of the Various Media

Range (M) Sub Length (M) Number of Nodes Common Mode
Transformer Coupled 78kbps 1400 3 64 277V RMS
Transformer Coupled 1.25Mbps 0.3 64 277V RMS
Free Topology 78Kbps 500 N/A 64 277V RMS
Power Line 10kbps 6000 N/A 64 N/A
Radio RLTU 15K*** N/A 64 N/A

*** Depends on antenna heights and gains. Line of sight only.


We hope this has been a useful introduction to Echelon Corporation’s LONWORKS® technology, and not too technical.

Davmark Group make things work. We do the hard work, not you.

Davmark Group provides advanced solutions using LONWORKS.

Extensive portions of this article were quoted verbatim from Motorola document BR1108/D, LONWORKS Product Line Brief and EB161/D, LonTalk Protocol. Davmark Group wishes to express their grateful acknowledgment to both Echelon and Motorola Semiconductor for these reference documents.


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