Fieldbus Foundation: 1st Foundation H1 Device Couplers are registered

Rigorous Fieldbus Foundation testing is said to assure interoperability of components at the fieldbus physical layer.


Device ITK Profile Final Specification

In October, the Fieldbus Foundation announced that its Device Interoperability Test Kit (ITK) Profile Final Specification (FS 1.0) were available. The purpose of the new specification is to offer an easy way of mapping field device requirements to the foundation's ITK versions, including unique Foundation technology features such as advanced field diagnostics.

A tool for troubleshooting and debugging devices, the Fieldbus Foundation's H1 and High Speed Ethernet (HSE) interoperability test kits help automation equipment manufacturers verify device interoperability as specified by the FOUNDATION fieldbus registration testing procedure. By using the test kits, device developers can run tests identical to those used by the foundation before submitting their device for official registration.

The ITK Profile Final Specification includes a set of tables listing Foundation technology features, and indicating whether the features are optional or mandatory at a particular ITK level. Profiles defined in the specification document contain features that may be incorporated into new device implementations. These features include, but are not limited to: standard block profiles, non-block features, extensible parameters such as "OPTS", FEATURES, etc., Device Description (DD)/Capability File (CF) technologies, and communication "stack" requirements.

The specification helps new fieldbus device suppliers to identify minimum required features for their products and allows existing equipment manufacturers to identify the latest requirements. For example, field diagnostics is optional on current ITK versions, but will become mandatory for all fieldbus devices in compliance with ITK 6.0, which will be released in mid-2010.

ITK devices support the latest advancements in field diagnostics, which build upon the existing, powerful diagnostic capabilities of FOUNDATION fieldbus equipment. They also add a greater degree of organization so field instruments can represent their diagnostics in a more consistent way.

Field diagnostics per the NAMUR NE107 recommendation provides a standard and open interface for reporting all device alarm conditions, as well as a means of categorizing alert conditions by severity.

The Fieldbus Foundation has also announced the availability of an Integrated and Visitor Host Interoperability Application Note (AN-013). The purpose of this new application note is to clarify how Integrated (also called Permanent) Hosts and Visitor Hosts can interoperate in order to allow a Visitor Host to interact with field devices in the presence of an Integrated Host.

Fieldbus Foundation registered the first Foundation fieldbus H1 device couplers, the organization announced in November. The new device coupler registration process provides automation end users with greater assurance of the interoperability of independently manufactured fieldbus physical layer components.

MooreHawke, a division of Moore Industries, and Pepperl+Fuchs are the first Foundation fieldbus device coupler suppliers to pass the registration process.

The Fieldbus Foundation's Foundation Device Coupler Test Specification (FF-846-1.1) defines a suite of vendor self-tests for fieldbus device couplers with spur short-circuit protection. The tests cover device coupler requirements as specified in the FF-816 FS 1.5 Physical Layer Profile, as well as the IEC 61158-2: 2003 standard. The registration process includes additional tests beyond the scope of these standards, which determine if a device coupler is fit for its intended purpose of preventing spur short-circuits from disrupting a fieldbus network.

The device coupler registration program initially addresses two classes of devices: Foundation device couplers and Foundation wiring blocks. Device couplers are a critical component of an H1 fieldbus network enabling connection of multiple field devices to the segment. Characteristically, these units will have ports for trunk-in, trunk-out and one or more spurs, with the requirement of spur short-circuit protection. Registered device couplers must be network-powered (dc/dc conversion is not included). Wiring blocks are simple devices with a minimum of one trunk input and one spur output. Registered wiring blocks may contain surge protection circuits, integral terminators or indicating LEDs, but cannot provide spur short-circuit protection.

Fieldbus Foundation manager-fieldbus products, Stephen Mitschke, commented, "With the initiation of device coupler registration, the Fieldbus Foundation is helping to ensure robust and reliable fieldbus physical layer performance. Registration signifies that a coupler is suitable for any fieldbus installation. End users can now have even greater confidence in Foundation-based automation systems thanks to our rigorous suite of device coupler test cases."

MooreHawke's registered

Trunkguard Series 200 (TG200) and Series 300 (TG300) Fieldbus Device Couplers utilize patented "Automatic Segment Termination" technology, which eliminates the most common installation error: segment failure from under- or over-termination. This approach also assures that local parts of a fieldbus segment will continue to function, even if remote parts are accidently disconnected. The TG200 Series is offered in 4, 8, 10 and 12 output (spur) configurations. The TG300 is offered in 4 and 8 spur models.

In addition, the TRUNKGUARD Fieldbus Device Coupler provide electronic and fully auto-resetting spur short-circuit protection that prevents segment failure caused by single device faults. Utilizing a "fold-back" technique, any spur that attempts to draw more than 48 mA is automatically switched off and not permitted any current flow until the fault is removed. During a short, only 4-5 mA is used-eliminating segment failures caused by overloading the segment power supply. With removal of the short, Trunkguard automatically reconnects the spur to the fieldbus segment.

MooreHawke's registered Trunkguard Series 300 Device Coupler (TG300) simplifies the use of Exd/Flameproof fieldbus devices in Zone 2 and Zone 1 by allowing "live" access for maintenance and eliminating the need for expensive Exd/Flameproof junction boxes. It enables fast and easy implementation of fieldbus systems by connecting multiple devices to a main fieldbus trunk in FOUNDATION fieldbus H1 networks.

Pepperl+Fuchs' registered R2-SP-N Device Coupler is available in five different models, with a choice of 4, 6, 8, 10 or 12 outputs (spurs). Each spur limits a short-circuit condition, thus ensuring that the remaining segment is adversely affected by a fault condition at one spur only. Energy limitation Ex nL (nonincendive) or Ex ic (intrinsically safe) at the spur is implemented with selected FieldConnex power supplies. The High-Power Trunk concept allows for maximum cable lengths and number of devices, which can be installed or maintained while the system is energized. In addition, use of a trunk "T-connector" enables exchange and modification of one segment protector without impacting other parts of the same fieldbus segment.

Pepperl+Fuchs' registered Modular Segment Protector is a device coupler for fieldbus according to IEC 61158-2. A trunk module connects the unit to the segment and has two outputs (spurs) connecting one field device to the trunk line. Expansion modules with four spurs snap side-by-side on a DIN rail with a system plug for interconnection. The segment protector provides a certified Ex nL energy limitation at each spur connection. This unit, along with the field devices, can be installed in Zone 2/Div.2 with devices maintained while the system is energized.

Registered FOUNDATION fieldbus products are listed on the Fieldbus Foundation's website.

- Edited by Mark T. Hoske, editor in chief, Control Engineering

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