Key points
Local user interfaces for digital valve controllers have been limited in the past, but new advancements have made these devices more intuitive, with easier access to information.
Byline: Andrina Helgerson, Emerson
The power and capabilities of digital valve controllers have expanded dramatically since the first electro-pneumatic positioners were introduced in the 1970s. These devices transitioned to full digital control in the mid-1990s and began to incorporate modular designs in the early 2000s. Despite all those improvements, the controller’s local user interface remained somewhat limited.
The introduction of HART provided easier configuration and some visibility to the controller data, but that information was difficult to access. To address these and other issues, new connectivity features are now offered or being developed for the next generation of digital valve controllers.
Valve controller connectivity
The earliest electro-pneumatic valve positioners were black boxes, offering little indication of their status beyond a few local pressure gauges. Technicians had limited capability to troubleshoot the device other than measuring the incoming 4-20mA signal and comparing it to the control valve’s physical position.
Connectivity took a large leap forward in the mid-1990s when digital valve controllers were released with HART capability, providing users with the ability to perform configuration via a HART handheld, and to query the device for basic alerts and failures. Unfortunately, HART required physically connecting to the 4-20mA loop which, if connecting directly to the device’s terminal box, required exposing the wiring terminals in the digital valve controller. Such access was often difficult in hard-to-access and hazardous area locations.
The latest generation of digital valve controllers addresses these shortcomings by incorporating a broad selection of local, remote, and wireless connectivity options.
Local user interface at the valve
Certainly, the most obvious connectivity addition for next generation digital valve controllers is a fully functional local display that provides users with the ability to access device information and troubleshooting diagnostics (Figure 1), as well as an LED status light which offers an immediate indication of the device’s status at a glance. For example, some displays can show a list of active alerts, along with recommended actions on how to fix problems.
Figure 1: The latest generation of digital valve controllers (Fisher™ FIELDVUE™ DVC7K shown) features a fully functional display, providing access to device information, diagnostics, and configuration in multiple languages
This same type of display can also guide users through an intuitive guided setup method to quickly configure and calibrate the digital valve controller. All these tasks can be performed at the valve without opening the device. More advanced units offer a wide range of languages to suit valve controller applications across the world.
The local display is useful for initial digital valve controller setup and local troubleshooting, and it can be accessed in hazardous locations without special permits or restrictive operating procedures, providing a significant improvement in connectivity.
HART connectivity
Of course, HART remains a viable means of accessing and configuring the next generation of digital valve controllers, but the newest devices feature a broadened HART data set, allowing access to an expanded suite of information. Current and historical information from multiple device sensors, extensive alert history, and diagnostics are all available via HART.
These new digital valve controllers also continuously monitor and store all sensor data. Should an alert occur, the measured variables before, during, and after the alert are available for analysis. These devices also incorporate an enhanced on-board memory, allowing the controller to store an extensive history of alerts that can be accessed and retrieved for analysis, even months after an event. This type of data is very useful for troubleshooting and root cause analysis.
Bluetooth® access
Bluetooth wireless technology is starting to be incorporated into field devices (Figure 2). In the past, there were significant cybersecurity concerns associated with such open remote communications. In response, Emerson’s Secure Bluetooth® Wireless Technology has been developed and is now being introduced into controls and instrumentation.
Figure 2: Bluetooth communications offer high-speed local communications without opening device covers, however there are cybersecurity issues associated with these remote connections. Recently introduced protocol revisions, such as Emerson’s Secure Bluetooth Wireless Technology, provide safe use of this technology.
In anticipation of the release of secure Bluetooth communications, a number of applications have been developed to leverage this technology. Similarly, the next generation of digital valve controllers have Bluetooth communications already built into the device, so this feature is ready to be enabled and utilised.
Advanced valve connection software
Whether the communications are established through HART or secure Bluetooth, there are a host of software applications available to take advantage of the advanced diagnostics, new sensors, and predictive analytics being incorporated into the next generation of digital valve controllers (Figure 3). These applications can run on local or cloud-based servers and be accessed from digital devices—such as cell phones, industrial tablets, and laptop computers—to monitor an entire plant or facility.
Figure 3: As cell phones and industrial tablets become common in plant environments, digital valve controllers can be securely and unobtrusively monitored via Bluetooth-devices.
These types of applications have been reengineered to take advantage of the latest security features, providing high-level monitoring and detailed diagnostics for either a single valve, a few critical valves, or every valve in a plant or facility. The software can access the wide variety of embedded sensors inside the valve controller, and it includes advanced analytics that continuously monitor valve performance, highlight existing and developing problems, and identify degrading control performance.
A recent introduction to the plant environment is the new Plantweb Insight™ Valve Health Application (Figure 4). This application uses wired or Wireless HART communication, allowing the software to access and monitor the valve controller without having to open the device. Of course, cybersecurity is a key component of these applications to protect equipment from unauthorised access.
Figure 4: New valve health applications incorporate analytic algorithms and advanced diagnostics to detect existing and developing valve problems. Alerts are prioritized so users can focus on the most pressing problems.
Whether the user employs HART, Bluetooth, or the local user display, the ability to access, configure, monitor, and troubleshoot next generation digital valve controllers has improved dramatically. That access has become critical because it empowers plant personnel to take advantage of the wealth of data available in these devices. Advanced connectivity provides visibility to the predictive data analysis embedded in the digital valve controllers, which can spot trends of declining valve performance, and alert operations personnel in advance of valve failure.
The technological advancement of digital valve controllers is moving quickly, so users should choose these devices wisely. The most advanced controllers either offer a host of communication protocols now, or they have embedded those communications into the hardware so they can be enabled and used when these emerging technologies are released, providing users with the flexibility to choose how they interact with their devices. These advancements will empower plant personnel to increase uptime, reduce maintenance costs, and improve performance for their control valves, and by extension entire units and plants.
All Figures courtesy of Emerson
About the Author
Andrina Helgerson is a product manager within the Instrument Business Unit at Emerson. She holds an Industrial Engineering degree with an emphasis on human factors from Iowa State University.
