Petr Ivanchenko, Honeywell Building Solutions, Regional Business Development Manager, Echelon Certified Instructor.
LON (Local Operating Networks) distributed control system technology was developed by the American company Echelon with a view to universal general industrial application. LonWorks™ technology is the intellectual property of Echelon, founded by Mike Markarula (Intel, Apple).
LonWorks™ is designed as an open technology that can be used free of charge by anyone who needs it.
Despite the fact that there are many distributed systems (Fieldbus) in the world, LON has firmly found its place in the market, occupying the niche of building automation. The reasons for this were the successful concept of building a system not so much as a data exchange protocol, but as a hardware and software complex.
LonWorks is not just a distributed control system, but rather a system with distributed intelligence, where devices can independently process events and have built-in software.
The optimal application of LonWorks technology is a field-level network for building automation, the features of which are a large, extended communication line and a relatively small amount of traffic within the segment.
By their concept, LON networks have a number of features:
• The technology supports the use of various signal transmission media, both wired (copper twisted pair, fiber optics), and radio frequency, infrared or transmission via the power supply network.
• Devices in the LonWorks network are equivalent. There is no division into main (Master) and subordinate (Slave) devices.
• The technology implements event-oriented logic: unlike centralized control systems, where the main network traffic is generated by polling slave devices, in LON networks the basis of traffic is made up of packets carrying information about changes in environmental parameters (events).
• Control networks built on twisted pair (approximately 85% of all LonWorks channels) support various topologies, including free.
• Each device has embedded software, programs are executed by event.
LonMark Association
LonMark is a non-profit association whose main goal is to promote and technically support LonWorks technology worldwide, and to provide support to its members. Today, LonMark unites more than 500 members.
Among them are equipment manufacturers, integrators, application developers, and end users.
Honeywell is a sponsor of the LonMark association (the highest membership category). A Honeywell representative serves as the Vice Chairman of the Board of the association.
The association tests and certifies LonWorks products. Detailed technical information and application software for certified LonWorks devices are available on the association's website. Certified devices are marked with the LonMark International icon.
Neuron Chip – the heart of any LON device
The hardware basis of LonWorks technology is determined by the Neuron Chip. This special microcircuit is contained in each LON network device.
The first Neuron Chip was released to the market in 1991. Today, 60 million LON devices are installed and successfully operating worldwide, in more than 300,000 systems. There are two types of Neuron Chip: the 3120 has built-in memory (ROM), and the 3150 uses an external memory device. Under an agreement with Echelon Corporation, Neuron Chip is manufactured by two manufacturers: Toshiba and Cypress.
Each Neuron Chip has a unique 48-bit identification code, written into the non-volatile memory of the Neuron during its production (the so-called Neuron ID). The Neuron microcontroller contains three 8-bit microprocessors, united by an internal bus. Two of them control the network data transfer based on the LonTalk protocol, and the third is designed to service the application part of the node software and interact with external devices.
In addition to the Neuron, the node may include an equivalent microcontroller (the so-called host processor) that performs tasks of interaction with external devices (if the computational or functional power of the Neuron is insufficient). Also, to expand the functionality of some Neuron models, it is possible to use external memory to store programs.
In addition to the processor, each device contains:
• Clock pulse generator
• Transceiver
• Input/output circuits
• Power supply circuit
• Service input and LED indication
LonTalk protocol (ANSI/EIA 709.1)
If Neuron Chip is the main hardware component of the technology, then the software basis of LonWorks is the open standardized LonTalk protocol. The LonTalk protocol, in the international classification ANSI/EIA 709.1 (ANSI — American National Standards Institute), is intended for use in control applications, and not in applications oriented to data processing. This protocol uses all 7 levels of the ISO standard model for communication data exchange in networks. This protocol is implemented on the Neuron chip, but can also be implemented on any other equivalent processor.
The protocol is an open and published standard that is available to everyone. To purchase documentation, simply contact the LonMark International association.
The LonTalk ANSI/EIA 709.1 protocol is not tied to any specific physical data transmission medium and ensures data transmission over a variety of communication channels using a variety of encoding methods. For example, the differential Manchester encoding method is used for twisted pair, and FSK modulation is used for work on voltage line segments and at radio frequencies.
The next issue of the bulletin will publish a continuation of the article on LonWorks technology. The types of software for developing and programming LON networks and the specifics of LON devices will be considered. Customers will be interested to get acquainted with real examples of implemented systems at retail and office real estate facilities.
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