Improving reliability and availability of fieldbus installations

Fieldbus Foundation updates device coupler test specification

The Fieldbus Foundation has announced the latest updates to its open, non-proprietary FOUNDATION™ fieldbus physical layer technology. Current enhancements to the H1 (31.25 kbit/s) device coupler test specification will help improve the reliability and availability of fieldbus control system installations, as well as optimize device interoperability and integration.

As part of a Foundation fieldbus infrastructure, device couplers or isolated device couplers (where applicable) are installed where the fieldbus trunk (i.e., home run cable) is connected to the various device spurs. Isolated device couplers are specifically designed to allow automation end users to connect more devices per coupler while permitting live segment work in hazardous plant areas. These couplers provide isolated, conditioned power to multiple fieldbus devices and protect against short circuits caused by excess current in a spur. By enabling more devices per segment, they also help reduce controller input/output (I/O) points and associated installation costs.

This device coupler test specification includes criteria from the international IEC 61158 standard and additional functional tests such as input impedance, short-circuit reaction time, and bus voltage consumption. The specification is designed for coupler manufacturers to perform a standard set of tests against their implementation. A team of volunteers comprised of current members of the foundation who supply coupler products, as well as end users employing registered couplers, developed the test cases.

The Fieldbus Foundation's Director-Fieldbus Products, Stephen Mitschke, commented, "The Fieldbus Foundation is committed to rigorous test procedures for all FOUNDATION devices, hosts and components. Our device coupler test specification is intended to provide a high level of robustness in fieldbus systems. The resulting registered products are tested to perform optimally with registered power supplies and conditioners, as well as registered H1 cable."

Mitschke added that the latest enhancements to the FOUNDATION fieldbus physical layer specifications will provide end users with greater confidence that registered fieldbus equipment can be employed in a tightly integrated, interoperable control system architecture that is well suited to the most demanding industrial environments.

To obtain this updated specification, visit the Technical Specifications page of the Fieldbus Foundation's website.