Customers in our industry traditionally insisted on multiple-light, audible-horn, annunciator-type panels for alarming and operator notification. We want to move forward with up-to-date HMI touchscreens and to incorporate alarming and important operating notifications there. We'd like this to be part of the normal HMI configuration with screens that look as much like the old annunciator boards as possible. What are some possibilities?
—from September '09 Control Design
Questions and More Questions
Think about how the machine's users would answer these questions.
- Do you currently have a structured process for understanding what adds to the cost of your process and reduces availability?
- What systems are in place that generate alarms, and do you analyze those alarms?
- Do you obtain key metrics from the alarm system, such as average/maximum alarm rate, standing alarms per interval, top 10 worst actors?
- When a critical failure occurs, do you have a reliable way to analyze the root cause?
- Do your operators feel they are overloaded with useless, distracting alarms?
Multimedia Alarming is a distributed enterprise-wide, alarm-notification system. It delivers real-time alarm information to you, wherever you might be. Alarms can be sent to your email, pager, fax, voice, text-to-speech, phone, marquees and more.
When looking to see if multimedia alarming would be a good fit, consider the following.
- Do you need instant notification on your facilities or operations around the clock?
- Do you need to send multiple alarms to different sources and people simultaneously?
- Would sending HMI alarms directly to pagers, Blackberry devices or mobile phones increase your productivity?
- Would an email log of your alarms be useful?
- Do you have marquees throughout your operations that people use to see alerts?
Tim Donaldson, director of marketing,
Modern HMI touchscreen panels, hardware and software include the ability to visually represent existing annunciator panels with graphical tools for color-coded indicators, alarm messaging preferences and even audio output. They also provide advanced alarm management, trending and historical logging capabilities that allow users to establish alarm patterns to troubleshoot problems faster. Modern HMI touchscreen products for machine control also help improve preventive maintenance and long-term equipment sustainability through the configuration software tools that often include functions for alarm analysis tasks.
Other benefits of migrating to HMI touchscreen panels include giving machine operators and maintenance more information with a touch of the alarm for instructions on how to resolve a problem. This extended capability can also be easily upgraded, changed or adapted through software for future improvements to the connected equipment, thus eliminating the need to rewire traditional annuciator panels.
Paul Ruland, product marketing – automation systems,
Siemens Industry, www.usa.siemens.com/automation
Comfortable and Familiar
CE HMI devices are a great fit for this type of application because they are inexpensive and the graphics displays can be "drawn" to very closely mimic any existing pushbutton implementation. Wonderware InTouch Compact Edition uses a common development environment with the larger scale HMI and SCADA applications so graphics also can be used for central control room applications.
A single panel can provide the same information as multiple annunciator layouts, as necessary, and to the right operator. Multiple output audible annunciation can be designed into the HMI simply by calling up the right audio file and playing it over a standard built-in audio output on the device.
Longevity is important for OEMs; the design and implementation of a system today must stand the test of time and be supported often for 10 years or more. By using a low-cost HMI device, this is easily achieved, even if a mid-life upgrade of hardware and software is implemented by the machine builder.
Lastly, should an interface design really be required, implementing this in an HMI is far simpler than re-engineering the physical hardware associated with a panel of old. HMI designs today can easily mimic the hardware and early HMI screens of yesterday, providing the required familiarity to existing operations personnel. But they are also versatile, so for example, if necessary, detailed additional information can be overlaid on the display, temporarily presenting this to the operator thanks to the non-rigid nature of the interface.
Keith Jones, product manager for visualization products,
Invensys Operations Management, www.invensys.com
Check Out Our Touchpanels
Today's HMIs not only can simulate the traditional annunciator-type panels, they can store a complete history of alarms, the time the alarm occurred, the reason it occurred and how long it was on. Our touchpanels can trigger alarms automatically based on PLC tags, display the picture of the machine or process and pinpoint or flash the area where the trouble is. These panels can send email alerts to maintenance personnel and also display messages on a marquee for plants where the decibel level is too high to hear audible alarms.
Shalli Kumar, chairman, CEO,
What About the Annunciator Panel?
Before the HMI possibilities are discussed one key question must be addressed. Can the annunciator panel be replaced by the HMI? A risk assessment should be conducted. Edward Marzal, president of Kenexis, provides criteria to consider with having a separate annunciator panel from the basic process control system (BPCS) if the initiating event causing the hazard is a BPCS failure or cannot be detected by the BPCS, if the consequence is significant; if operator actions are required outside the BPCS, or if reliability of the BPCS. Is the BPCS fault tolerant?
If the risk assessment determines the annunciator panel should continue to be functional with the BPCS, then the ANSI/ISA 18.2 Management of Alarm Systems for the Process Industries provides further recommendations on how to communicate annunciator alarm state information to the alarm log, prevent redundant alarms in the annunciator and BPCS, prevent the need for redundant acknowledgement in the control system, and be designed so that the alarm layout on the annunciator follows a consistent methodology.
Should the risk assessment allow the alarm handling to be moved from the annunciator to the HMI display, first consider the basic functionality of the annunciator to be replaced.
The HMI should show no confusion between alarm states—active state and operator acknowledged states; is in a prominent location in the control room and easy to see from any operator workstation position; and lets the operator acknowledges the alarm without changing displays.
Further, the HMI display can potentially provide first-out alarm information and is always visible to operations during upset conditions. That might require a dedicated monitor.
Using the standard HMI alarm summary display may not be sufficient for the annunciator alarm points. Marzal also points out studies from NUREG/CR-1278 that show an increase in human error probability when displays that are part of a well-delineated functional group on a panel versus an array of similar-appearing displays identified by label only.
Bob Weibel, president and CEO,
Touch on the Differences
This is a common request as it seems obvious that the current HMI-based technology can perform the alarm management functions needed today. While some customers have switched over to this concept, it has not been widely accepted due to some fundamental differences between the two approaches.
HMI-based systems with touchscreens require a certain degree of customization to incorporate the annunciator functions and alarm management screens. Each customer has its own unique requirements, making it difficult to design a one-size-fits-all type of solution. This becomes obvious when you visit a few control rooms and see that every installation has a unique arrangement for the quantity of alarms, the size of the annunciator display, which is important for retrofitting an existing panel, and the various functions included. Changing to a standard footprint for all will create some resistance from the operators that are accustomed to a specific arrangement. The annunciator type panels are available in a wide variety of sizes and shapes, so there is no customization required. In many cases, the input wiring is already in place making it easy to replace one system with another.
When comparing the cost of ownership, the annunciator wins hands-down as today's modern annunciator panels use LED technology, which extends the life of the lamps for many years, often exceeding the life of the equipment. The annunciator panels are modular designs with multiple I/O cards that can be easily replaced if need be with low-cost replacements. Parts are typically available for the life of the product—usually 25 years. HMI-based solutions typically require software and hardware upgrades to stay current with manufacturers' support plans as the technology changes at a much faster rate than annunciator systems.
The cost of ownership for either approach is a common source of debate. An HMI-based alarm screen can seem cost-effective on the surface, but remember to include all of the hidden costs, including special programming, configuration, installation and re-training of operators that are familiar with other systems. In an effort to save money and consolidate equipment, some HMI systems used for control applications are equipped to provide the monitoring screens in place of the annunciator panels. While effective, it puts all of your eggs in one basket, should there be a single point of failure. An effective alarm management system needs to be reliable with no single point of failure. Most annunciators are designed this way as multiple lamps are provided per window for redundancy, I/O boards are limited to a few points to isolate any failure and fail-safe systems are employed as a stop-gap measure.
Steve Bleier, product manager,
Ametek Power Instruments, www.ametekpower.com
Alert the Operator
A blinking light and loud horn on a panel tell an operator something is wrong. A well-designed HMI is infinitely more effective to quickly alert the operator to specifically what is wrong and what to do.
While effective, stack lighting is limited to just a few colors. Computer-generated graphics can be any color, shape, size, intensity or blink rate, can include text and can even present video clips detailing required operator action—all to provide the operator with as much useful and timely information as possible to properly maintain or shut down a critical process.
Wide-format displays can provide extra dedicated alarm areas. Most HMI graphic applications still use the traditional 4:3 video aspect ratio and fit properly on standard monitors. With new wide aspect ratio displays, such as the 22-in. DM522 from Pepperl+Fuchs, system designers can designate this extra width to alarming. In this scheme, the full HMI graphics system continues uninterrupted on the majority of the display in traditional 4:3 format. The remaining extra display area provided by the wide aspect ratio is then reserved for alarming, often current and historical.
Rick Tomfohrde, HMI business development manager,