Busting Myths About Foundation Fieldbus

Foundation fieldbus is compatible with much of the existing wiring found in today's plants. Test kits are available to determine if existing wiring is compatible with Foundation fieldbus technology, but overall the technology is compatible with existing wiring. Special wire or cable may bring installation benefits, but is not required.

Myth: Foundation Fieldbus for Process Safety Systems Will Not Work

TÜV granted Protocol Type Approval for the Foundation fieldbus Safety Instrumented Functions (FF-SIF) specifications in 2006. The Fieldbus Foundation specifications comply with the IEC 61508 standard for functional safety of electrical/electronic/programmable electronic safety-related systems requirements, up to and including Safety Integrity Level 3 (SIL 3). Many major end users, such as Aramco and Shell, have beta systems running FF-SIF logic solvers and devices running today, and have openly stated that they would like to deploy this technology on all of their upcoming major projects.

Why Safety Instrumented Functions?

Figure 3. Improved safety and operability, plus reduced costs makes a strong argument for implementing SIF.

No changes were made to the fundamental H1 protocol for implementation in safety instrumented systems, but additional device diagnostic functions and fault detection capabilities were required. In addition, the primary advantage to using FF-SIF as the network for safety applications is the network diagnostics that are possible. Traditional analog-based networks lack the ability to detect noise, corruption and faults in the network.

Space-Saving Simplicity Figure 4. Foundation fieldbus technology gives users diagnostic data from their devices, reduces unplanned downtime and cuts down on the amount of wiring, I/O and associated labor and infrastructure required in a conventional 4-20mA system.

More importantly, the data handling capability of Foundation fieldbus technology means that you can commission your safety system faster. Users modernizing their legacy safety instrumented systems must also replace the entire system, from the devices to the logic solver, to be compliant with safety standards such as ISA 84 and IEC 61508 and 61511. FF-SIF offers reduced time to start-up, easier regulatory approval and reduced installed costs for process safety systems.

Myth: Foundation Feldbus is Just for the Refining or Chemical Industry

Today, 10 of the top 20 food and beverage companies and 24 of the 25 top pharmaceutical companies are using Foundation fieldbus technology. Foundation fieldbus technology makes it easier for regulated industries to achieve compliance. Pharmaceutical manufacturers are increasingly designing their plants for fast-track construction by connecting multiple pieces of OEM skid-mounted equipment. Foundation fieldbus technology makes it easy to integrate different skids from different OEM suppliers quickly under a single network and automation infrastructure. The reduced footprint of Foundation fieldbus also lends itself well to the limited space requirements of many skid-mounted systems. Dealing with changes in scope that include adding new field devices after initial segments were installed is less painful because it's not necessary to install a home-run cable for the device to the control cabinet.

Myth: Fieldbus Diagnostic Data Results in a Flood of Alarms and Alerts

Foundation fieldbus devices do provide a greater level of diagnostic data. Fieldbus devices do not, however, create alarms for operators by default or issue an alarm whenever there is a diagnostic issue with the device. Operators should only be alerted to device problems when they can have an impact on their operation. Fieldbus diagnostics can also be prioritized based on the impact a particular failure has.

In today's digital age, there is no reason not to include an evaluation of Foundation fieldbus technology for your automation requirements, whether it is a modernization project or a grassroots facility.