The challenge for most is doing it with constrained budgets and limited resources to get more from assets they already have.
The smart field devices enabled by Hart communication—which may already be in your plant—are an underutilized resource that can help meet this challenge. These devices are loaded with intelligent information to help improve operations and lower costs.
Using the intelligent capabilities of Hart-smart devices for set-up, commissioning and troubleshooting provides a valuable but limited benefit. Real-time integration with plant systems unlocks the power of these devices for maximum benefit, allowing the intelligent capabilities to be used for operational improvement. In other words, Hart can provide the heart of an asset management solution.
Hart-smart field devices should be thought of as real-time data servers with intelligent information—open for business 24 hours a day, seven days a week. Every Hart device, regardless of manufacture, has 35 to 40 data items of rich information that is updated continuously and is available for real-time application. These data items include device status, diagnostics, process variables, device identification, calibration and sensor information. The inherent intelligence of these devices allows them to continuously assess and monitor their performance and supply device status information with every communication.
A unique characteristic of Hart communication is that devices support two simultaneous communication channels on the same wire. The 4-20 mA analog channel carries the primary variable control signal. This is still the fastest way to move control information to and from the process connection and the controller. The Hart digital channel provides real-time access to all device information and data items.
Hart-enabled control and safety systems should use both channels for continuous real-time communication between the intelligent input/output (I/O) sub-system and device. Complimentary use of both communication channels provides a higher level of control security and loop integrity, far beyond what is possible using either channel alone.
New Hart-enabled control systems and intelligent I/O sub-systems communicate continuously with connected Hart devices over both communication channels. Systems using only the 4-20 mA analog channel leave an “information gap,” as all intelligent device information is lost and the control signal is not secure.
Real-time Hart communication eliminates the information gap by allowing systems to secure the analog channel, continuously validate control loop integrity, and detect problems with the device or the device-to-plant connection within seconds of occurrence. Plant operators are provided with early warning to problems that previously could not be detected before negative impact to the process.
Integrating Hart communication with plant systems is easy and cost effective. First, visualize ways that Hart communication can improve operations in your plant. Identify your installed Hart-smart devices and confirm that all critical measurements and control variables are Hart-enabled. Get training for your staff on the capabilities of Hart communication and real-time applications with systems. Talk with your suppliers about the data in their Hart devices and tools they can provide.
Real-time integration of Hart-smart devices into plant control and safety systems is a key enabler for asset productivity improvement. It paves the way to improve operations, increase plant availability, lower maintenance and operational costs and avoid costly process disruptions or unplanned shutdowns.
Ron Helson, P.E., [email protected], is the executive director of the Hart Communication Foundation, in Austin, Texas.
See sidebar to this article: Things you may not know about Hart
