What Is Fieldbus Engineering? Technical Approach

The purpose of this article is to explain how to perform Fieldbus engineering and what precautions to take during the engineering. More specifically, this document is intended to provide a guide for constructing a consistent loop from a DCS to Fieldbus devices.

What Is Fieldbus Engineering?

The conventional communication of signals between field devices and a control system (hereinafter referred to as DCS) has been performed using analog signals of 4 to 20 mA obtained by normalizing physical measurement using 0 to 100 % intervals. When using this approach, the field device side and the DCS side are designed separately. In other words, the DCS engineering, which covers the area from the reception of normalized analog signals by the DCS to the generation of function blocks, was performed separately from the engineering on the field device side.

However, in a system implemented with FOUNDATION fieldbus devices, the multiple fieldbus devices communicate to a DCS control station through a fieldbus cable using the digital signals.

The control signals are communicated via the function blocks in the fieldbus devices (hereinafter, the referred to as fieldbus blocks).

The engineering works for a fieldbus system comprise not only the physical layer designs for device deployment, fieldbus segment structure, length of cables, power supply capacity and so on, but also the functional designs in DCS system including the function block diagrams, processing timing, data communication timing and so forth. Moreover, since the power supply capacities or fieldbus block diagrams are correlated with deployed fieldbus devices, so that the DCS functional engineering works and the Fieldbus devices engineering works should be comprehensively collaborated.

The following topics will be explained.
• The tasks involved in DCS generation, including definitions related to Fieldbus devices
• Connection with Fieldbus devices
• Downloading definition information to Fieldbus devices.

This article explains how to engineer the FOUNDATION fieldbus (FF-H1) communication module (ALF111) installed on FFCS, FFCS-L, FFCS-V, KFCS2, KFCS, RFCS5 and RFCS2 in CENTUM VP systems.

This article explains following key points

• What is meant by fieldbus?
• What is fieldbus and how does it work?