Jay Thompson, Wendy Coates
When first learning about Human Machine Interface (HMI), we were discussing the accident at 3 Mile Island in New York which was caused, in part, because a critical alarm went unnoticed. It was buried in a mess of flashing lights and extraneous alarms which distracted the operators. Of course, this was only clear in hindsight, but the fact remains that for many companies in the petroleum and chemical industries, a safe and effective HMI can be very beneficial.
HMI describes all the components that an operator uses to interact with pumps, valves and tanks in the field. The International Society of Automation (ISA) published a standard regarding HMI for Process Automation Systems which lists some examples shown in Figure 1 that include a monitor, keyboard, mouse, etc. ProSys’ Interface Dynamics v3 (IDv3) software is able to meet the needs required by this standard. IDv3 has a shape library of customized shapes, but is also able to support the generic shapes and functionality.
ISA-d101.01, Human Machine Interfaces for Process Automation Systems
Below are some of the ways ProSys’ services and software align with the ISA 101 standard:
- In section 4.2.3, a toolkit is developed as part of the system standards. This is where IDv3 would come in as a third party including configuration, setup and support, display templates and static and dynamic shapes. As standards change along with technology, IDv3 is constantly updated to improve performance.
- Next, IDv3 enters the design process under Display Design in section 4.3.1. A conceptual design is created with input from operators and engineers. This ensures the requirements are included in the design before any detailed displays are created.
- The longest part of the initial process is in section 4.4.1 where the HMI team builds all the displays.
- In section 4.4.3, time is allotted for testing any new versions of IDv3 before it is installed on any consoles.
- Then, verification is finalized with documentation, as in section 4.4.6.
- Section 5.1 discusses the general principles of HMI. IDv3 ensures that the main tasks of process monitoring are supported with analog and digital components of our dynamic shapes. Indicators, such as variable bars, are provided to show limitations on certain controls. Audio supports enable operators with monitoring as well. Some dynamic shapes enable easy control by entering different parameters or choosing to change an operation. Consistency is key in making sure all static shapes, text boxes and colors stay the same throughout every display. For example, all text has the same style of Tahoma 10pt. bold, and all lines assigned the color green use the same RGB colors. Also, all static shapes are copied from our static shape library, and the same applies with our dynamic shape library. The Navigation Bar helps in the ease of navigating throughout the displays of a specific domain or section. All of this joined together helps the operator with decisions to help run things efficiently.
- The user’s sensory limits are taken into account in section 5.3. Some operators may have limitations with color blindness. IDv3’s shapes are designed to show alarms not only in different colors, but different alarm shapes and sounds as well. Only certain colors and sizes are used for process lines. If they are considered a main part of the process, larger arrows and thicker lines are used. If they are a minor part of the process, such as gases or water, then smaller arrows and thinner lines are used.
- Most of the display styles created with IDv3 are process control displays. Overview, detail, plot plans, ESD and pop-ups are examples of other display styles that can be created, as discussed in section 6.2.
- As for display hierarchy in section 6.3, the HMI team designs 4 levels:
- Level 1 - trends
- Level 2 - overviews
- Level 3 - detailed displays
- Level 4 - diagnostic, pop-up or even point details
- Section 7.2.1 discusses data entry methods. In IDv3, control shapes have grayed areas to show where data can be entered. Other areas are white and are read-only. Also, when a control shape is clicked, a drop-down shadow indicates it has been selected.
- Navigation methods are discussed in section 7.2.2. Hyperlinks are one way to help navigate to corresponding displays, but the main source for moving through displays is the Navigation Bar. This allows the operator to move throughout their domain of displays. The navigation network design is set up like the hierarchy of displays discussed earlier in section 6.3. The top tier contains all corresponding level 2 displays, then all level 3 displays and the last tier contains level 4 displays. The Navigation Bar, a drop-down menu, is located at the top of every display, so there is no need to move throughout the displays one by one. Alarm navigation is involved as well.
IDv3 is designed to be a user-friendly interface. If needed, ProSys provides hands-on training for engineers and operators on site. Software maintenance and support is offered following site visits as well.