ISO IEC 14908-2-2012 PDF

Full title and description

Information technology — Control network protocol — Part 2: Twisted pair communication. This international standard defines the free‑topology twisted‑pair physical channel (including link power) used with the ISO/IEC 14908 control network protocol (LonWorks family) for local control networks.

Abstract

ISO/IEC 14908-2:2012 specifies the complete physical layer (OSI Layer 1) for the free‑topology twisted‑pair channel used in control network systems. It covers the electrical and mechanical characteristics of the medium, topology limits (free, bus, star, loop or mixed), the interface to the MAC sublayer, frame/physical signalling (Differential Manchester at 78,125 kbit/s), link‑power delivery on the data pair, node and segment power limits, and related installation and cabling requirements. The document is intended to be used together with ISO/IEC 14908-1 (protocol stack).

General information

• Status: Published.
• Publication date: February 2012 (ISO publication record lists 2012-02; IEC catalogue shows 2012-02-14).
• Publisher: ISO/IEC (published under ISO/IEC JTC 1/SC 6).
• ICS / categories: 35.200; 35.240.99.
• Edition / version: Edition 1.0 (2012).
• Number of pages: 16 (ISO/IEC catalogue and IEC listing indicate 16 pages in the published international standard).

Scope

The standard specifies the free‑topology twisted‑pair channel used with the ISO/IEC 14908 control network protocol stack. It defines physical signalling (Differential Manchester at 78.125 kb/s), cabling and topology limits (free‑topology and bus variants), node composition and electrical interfaces, link power delivery on the data conductors (link‑powered nodes and source requirements), cable termination, repeater and segment configuration rules, and the physical interface to the MAC sublayer. It is intended for local control network applications such as building automation and other distributed control systems and is used together with ISO/IEC 14908-1.

Key topics and requirements

• Physical signalling: Differential Manchester encoding, 78 125 bit/s data rate for the twisted‑pair channel.
• Topologies supported: free (FT‑10), bus, star, loop or mixed topologies with specified maximum segment and stub lengths.
• Link power: provisions for delivering DC power on the same two conductors as data (link‑powered nodes), including source and passive coupler requirements and voltage/current limits.
• Node and segment limits: node counts and power budgets for link‑powered and locally‑powered nodes; constraints for mixed configurations.
• Cable, termination and EMC considerations: cable type/specifications, termination schematics for free‑topology and bus segments, and electromagnetic compatibility guidance tied to physical layer behavior.
• Interface to MAC: physical layer protocol data unit, frame format and transmit waveform definition for the MAC sublayer interface.

Typical use and users

Typical users are systems integrators, building‑automation designers, control‑system manufacturers, equipment installers, and test/verification laboratories who build or commission LonWorks/ISO‑14908 control networks. Common applications include HVAC control, lighting and shading systems, access control, energy management, street and outdoor lighting, and other local automation systems where a robust, low‑speed, link‑powered twisted‑pair medium is required.

Related standards

ISO/IEC 14908-2:2012 is part of the ISO/IEC 14908 series (control network protocol). Closely related parts include ISO/IEC 14908-1 (protocol stack), ISO/IEC 14908-3 (powerline channel specification) and ISO/IEC 14908-4 (IP tunnelling channel). The series corresponds to regional standards such as EN 14908 (European) and ANSI/CEA‑709 (US). Implementers often consult the companion parts for higher‑layer protocol rules and for alternative channel specifications.

Keywords

Control network protocol, LonWorks, twisted pair, FT‑10, physical layer, link power, Differential Manchester, building automation, ISO/IEC 14908.

FAQ

Q: What is this standard?

A: ISO/IEC 14908-2:2012 is the part of the ISO/IEC 14908 family that specifies the free‑topology twisted‑pair physical channel (including link power) used with the control network protocol.

Q: What does it cover?

A: It covers the complete OSI Layer‑1 specification for the twisted‑pair channel: signalling, frame/physical formats, cabling and topology rules, link power delivery and source requirements, node and segment configuration limits, connector/termination details, and the interface to the MAC sublayer.

Q: Who typically uses it?

A: System and product designers, manufacturers of networked control devices, building automation integrators, electrical installers and test laboratories that implement or verify LonWorks/ISO‑14908 control networks.

Q: Is it current or superseded?

A: As of its ISO record it is published (2012) and listed as the first edition; ISO standards are subject to periodic review. Regional adoptions (for example some EN variants) have their own publication and revision histories, but ISO/IEC 14908-2:2012 remains the international publication for this part. Users should check the official ISO/ national‑body catalogue for any subsequent confirmations or revisions before relying on the standard for new designs.

Q: Is it part of a series?

A: Yes — it is one part of the ISO/IEC 14908 series (control network protocol). Companion parts define the protocol stack (Part 1), powerline channel (Part 3), IP tunnelling (Part 4), and related application/implementation material in other parts and regional EN variants.

Q: What are the key keywords?

A: Key keywords include: twisted pair, link power, physical layer, Differential Manchester, FT‑10, control network, LonWorks, building automation, ISO/IEC 14908.