Busting Myths About Foundation Fieldbus

The AG-181 System Engineering Guidelines are the collected wisdom of many thousands of hours of fieldbus engineering and implementation experience. AG-181 can save you a lot of time and trouble if you are new to the technology and can be downloaded at no charge from the Foundation website under End-User Resources.Up to 75% of all start-up delays directly relate to instrumentation and controls. Foundation fieldbus technology can make commissioning easier and reduce overall commissioning times by as much as 85%. This results in faster plant start-up and faster time to production.

If you're a first-time implementer, or if Foundation fieldbus technology is being deployed at your site for the first time, it makes sense to invest in some training for your instrument technicians, operators and other people who can benefit from the technology. Training is a necessary investment, but training is highly accessible and does not have to break the bank.

Choosing the right engineering partner can also reduce installed cost. References are important. A growing number of engineering firms, from large engineering contractors to independent systems integrators, are becoming well-versed in Foundation fieldbus engineering best practices.

The real cost benefit to Foundation fieldbus technology is at the operations level. Numerous end users have avoided unplanned shutdown due to the diagnostics and function-block capabilities of Foundation fieldbus.

Many end users view maintenance as one of their key costs that can be cut. End users have estimated that more than half of maintenance activities result in no action. Foundation fieldbus technology with its predictive diagnostics can help users develop a proactive maintenance strategy that avoids unnecessary trips to the field for routine scheduled maintenance.

Myth: I Don't Need to Invest in Fieldbus When There Is Wireless Technology

Wireless technology has many advantages, but fieldbus and wireless technology are not mutually exclusive. Wireless in control applications is a long way off, and no end users are going to replace their entire control system infrastructure to support only wireless devices. The Foundation has made it a policy to coexist with industrial wireless technologies for process automation. Through our Wireless and Remote I/O project (WIO), the Foundation has generated specifications for gateways to incorporate either ISA 100.11a or WirelessHART data into Foundation fieldbus systems. Combining the wealth of diagnostic data in wireless devices with the capability to manage that data and turn it into useful information in a fieldbus system is a powerful solution.

Figure 1. End users estimate that more than half of maintenance activities result in no action. Predictive diagnostics can help users develop a proactive maintenance strategy that avoids unnecessary trips to the field for routine scheduled maintenance.

Myth: There Aren't Enough Systems Integrators with Good Project Implementation Experience

With thousands of systems installed, there is a substantial body of knowledge that has been established around successful implementation of Foundation fieldbus projects. The list of both suppliers and systems integrators with experience in implementation is substantial. Representatives from leading engineering firms are on the Fieldbus Foundation End User Advisory Council, and were instrumental in the creation of the System Engineering Guide.

Myth: Control in the Field Poses Risks and Compromises System Availability

Figure 2. Control in the field produces measurably faster response times.Control in the field is a chief enabler for achieving high-availability control and single-loop integrity. If there's a malfunction in the HMI that produces a loss of visibility into the process and stops communication with the controllers or any other component in the system, the control loops, including intelligent field devices, actuators, positioners and the network remain unaffected. In cases where control resides in the DCS, field-level control can add another level of redundancy. Many end users have already managed to avoid unplanned downtime when field level control took over after a failure in the system. Field-level control means not only increased availability and reliability, but also increased flexibility. In addition, controllers are free to handle higher-level control functions, such as advanced control and optimization.

Recently, U.K.-based Industrial Systems and Control Ltd. (ISC, www.isc-ltd.com) released a study called "Control in the Field: Analysis of Performance Benefits." In a series of illustrative simulation studies, ISC determined that control in the field has the potential to offer improved control-loop performance due to its ability to offer faster sample rates and shorter latencies in the read-execute-write cycle of a control loop.

Benefits of Control in the Field Benefits include Improved control loop performance Increased reliability & availability Improved loop integrity Reduced loading on DCS/PLC and network Lower capital and installation costs Reduced operating costs

Many end users have taken advantage of control in the field for years, and have had no problems with system availability or fault tolerance. Applications where control in the field are especially effective include compressor anti-surge control, many flow and pressure loops, and some fast temperature, pH, position and speed loops.

Power generation has long been one of the major users of Foundation fieldbus, even in nuclear applications. There are many important pressure and flow loops in a typical power generation facility that have an impact on overall plant performance, and can determine how fast a power generation facility can handle load changes or increase process efficiency.

Myth: I Can Get Most of the Field Diagnostics I Need from Other Technologies

Some network technologies offer diagnostic information, either digitally or through 4-20mA technology. Digital networks can handle more diagnostic data than their analog counterparts can, but their real value goes beyond diagnostic data. It's what you do with all that data to turn it into useful information to help you run your business. Foundation fieldbus technology has the ability to take large amounts of data from field devices, digital valve positioners and other instruments, and turn it into useful information.

Problem resolution hinges on the ability of systems to put data into the appropriate context. The data from Foundation fieldbus devices is constantly being updated. Instead of having to poll devices for data, the data is pushed to the applications and the people that need it when they need it. Data is prioritized to avoid alarm flooding. The data is time-stamped, and you can archive and retrieve it. Foundation fieldbus technology also has peer-to-peer communication capability, allowing devices to communicate with each other, which significantly expands the diagnostic capability of the overall system.

Myth: There Are Interoperability Issues with Devices

One of the founding principles of the Foundation is the support of interoperability—the ability to operate multiple devices from multiple manufacturers in the same system without loss of functionality. The H1 Interoperability Test Kit (H1 ITK) tests the functionality of a device and its conformity with Foundation fieldbus function block and transducer block specifications.

Diagnostic Data Provided by Registered Foundation Temperature Transmitter Statistical process monitoring: Uses process "noise" to detect process problems such as hydrate formation, scaling formation, thermowell coating, etc. Predictive thermocouple degradation diagnostics: Process/cold-junction sensor failures, sensor drift, configuration error. Extreme temperature tracking: Heat conducted from integral sensor to transmitter housing, transients.

An excellent tool for troubleshooting and debugging devices, the test kit includes all hardware and software required to ensure a manufacturer's complete device interoperability as specified by the Foundation's official registration testing procedure. The H1 ITK has now been updated to support field diagnostics capabilities, which standardize how all devices communicate their diagnostic data to the host system and asset management system, regardless of the vendor.

The Fieldbus Foundation also offers an extensive Host Registration Program. The foundation's Host Profile Registration Process requires that the host profile under test must support a clear set of required features. Under the registration process, hosts successfully completing the test requirements are authorized to bear the official Foundation fieldbus product registration symbol. Hosts may include configuration tools, recording devices, alarm display panels, HMIs or systems with a combination of functionality.

Myth: Fieldbus Is Only Good for New Projects

Foundation fieldbus technology is well-suited for modernization and migration projects, not just for large grassroots applications. According to ARC Advisory Group (www.arcweb.com), control system migration is the biggest issue facing end users today, and the installed base of process automation systems reaching the end of their useful life is worth around $65 billion. Over the years, many systems have been upgraded in a phased manner, usually at the application level. Today, we see more and more of the I/O, wiring and control infrastructure that needs to be replaced.

More than anything, users are looking to avoid a functional replacement in their migration strategy—replacing their old system with a new system that has exactly the same functionality and architecture. As more end users replace their legacy hardware and applications, they are realizing the value of Foundation fieldbus technology for getting more diagnostic data from their devices, reducing unplanned downtime and cutting down on the amount of wiring, I/O and associated labor and infrastructure required in a conventional 4-20mA system.

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.

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.