An introduction to visualization in industrial automation
In this post, I’ll introduce you to the concept of visualization in industrial automation. After reading this post, you should be able to:
Let’s start by talking about UI.
A User Interface is an interface that lets someone interact with a device.
An example of a user interface can be found on a microwave oven where you press a button to start cooking your food and a display shows you the time left until the process is finished.
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On a plant floor, regardless of what customers might be manufacturing, processing, assembling, or packaging, they are taking a similar journey from point A to point B - turning raw materials intosellable products.
During that journey, operators need to be able to:
This interaction occurs with a constant exchange of data between the operators runningand overseeing the process and the process equipment through operator interfaces.
In the past, the exchange primarily happened through hard-wired operator interfaces, like pushbuttons, selector switches, gauges, and stack lights
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Today, in addition to the hard-wired controls, operators can use networked electronic operatorinterface terminals, software installed and running on Industrial-rated computers, tablets, and mobile phones to extract more information from a process. These devices are commonly referred to as Human Machine Interfaces, or HMIs for short.
HMIs take less effort to install and maintain than hard-wired interfaces because there are fewer individual components to install and wire.
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As well as interfaces on individual machines, there are electronic interfaces for a full plant. These interfaces typically sit in a central control room.
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All of these interfaces are used to read the status of a process and control a process.
The HMI has evolved to become the central point for decision-making in manufacturing and industrial plants - whether for a standalone machine or across distributed systems.
The demands put on the HMI only continue to grow as manufacturers seek to take advantage ofnew enabling technologies and differentiate themselves from the competition.
Here are three of the main drivers for the increasing importance of visualization:
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All of the devices shown here visualize a process for an operator.
Selecting the right solution depends on functionality, cost, location, certification required, amount of information required to view and control, as well as the existing infrastructure at the site.
As we saw earlier, these interfaces can be installed on the machine, in the control room, or distributed throughout the facility.
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The most basic HMI devices transfer information in a single direction. They send information to the system or they indicate the status of the system.
Most status or output devices in this category are limited to displaying only alpha-numeric information such as alarm messages and part quantities.
Examples of simple HMI devices like this are buttons, signal lights, and text displays.
More sophisticated HMI devices offer both input and output data transfer. They typically support graphical displays and more data exchange. This helps an operator to understand and modify a process.
When we are talking about visualization in industrial automation, we are generally talking about these more sophisticated solutions.
The more sophisticated, bi-directional communication HMI solutions can be split into twocategories: Closed System and Open System.
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A closed system is typically an HMI panel. We say the system is closed because it can only perform a single function: run an HMI application. Upon powerup, these devices simply execute the HMI project that has been configured and downloaded to them.
Dedicated HMI devices provide some unique advantages in manufacturing.
They are tested to very specific global standards, industrial environments, and temperatures.
For security, with specially constructed operating systems, these devices are also much less susceptible to viruses or malware. In fact, many units require no anti-virus software to be installed at all.
Dedicated devices are designed to run for extended periods of continuous runtime.
Once a design has been implemented with enough capacity to withstand anticipated growthand application evolution, the expectation is that future investments in the same product will behavein the same manner. This is not necessarily true for commercially available computers with off-the-shelf operating systems.
Lastly, they are easier to maintain and support. Network communications are either built-in orsimple to add-on and configure.
Traditional PC-related maintenance tasks such as backing up and restoring a system state don’t require additional software.
System upgrades are much easier to perform with packaged solutions rather than miscellaneous service packs and individual patches.
Additionally, mechanical moving parts such as spinning hard drives are replaced by more reliablesolid state storage mechanisms.
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In contrast to closed solutions, open systems provide multi-functional capability allowing formore creative uses.
Many of these systems are built on a standard Windows or similar commercially available operating system, allowing users to run an HMI project as well as many other compatible applications on the same PCs, tablets, or smartphones we use all the time.
The newest, fastest, most advanced technologies are those developed on open platforms. Value-added solutions combine a controller and an HMI all in the same piece of hardware. On the technology curve, the latest operating systems, fastest components, and more memory make these solutions suitable for either stand-alone or server/client architectures and improv eata collection performance.
Now that we know a bit about the types of HMI solutions that are available, let’s talk about some of the common features that are available in HMIs.
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A well-designed HMI application has an effective hierarchy of displays that guides users through the system. The hierarchy provides them with progressively more detail as they move through different levels of HMI displays for information and data.
Some common displays include;
Login
A login display is a home display in the HMI application that provides users a way to log in.
You can assign different levels of access to the HMI displays within the application based on the credentials of the logged in user.
Menu
A menu display is a navigation display that provides users with a high-level view of the displays and functional areas within the operator interface application.
Users should be able to navigate to progressively more detailed displays from a menu display.
Process Overview
A process overview display is a high-level HMI display that provides users with an overview of the process being controlled or monitored. The primary purpose of a process overview display is to provide situational awareness, but it is not generally used to execute any controls.
From these displays, however, users should be able to navigate to additional displays that represent specific process areas.
System Status
A system status display is a high-level HMI display that provides users with one place to review the health and status of the processes and devices that are being controlled and monitored from the operator interface application.
Process Area Display
A process area display is a mid-level HMI display that provides information about a specific process area that is usually within the control of the user. Process area displays allow users to effectively monitor the process and are often the main control interface for performing routine operational tasks.
From these displays, users should be able to navigate to detail displays related to the process being represented.
Equipment Overview
An equipment overview display is a mid-level HMI display that provides information about a specific collection of equipment. An equipment overview display is often used to view all equipment of a certain type.
For example, you could have an equipment overview display that shows all your tanks. From this display, you could select a specific tank and navigate to a tank detail display within the collection.
Equipment Detail
An equipment detail display is a detailed HMI display that contains all available information for aspecific piece of equipment. For example, an equipment detail display for a specific tank or a specific pump.
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As for look and feel, busy, cluttered graphic elements common to traditional HMI displays have given way to a much more modern appearance in automation today. Too many animations and colors create distractions for operators, making it difficult to identify alerts and resulting in a loss of productivity.
With the help of today's standards like ISA 101 and ASM, operators are more likely to be presented with much simpler graphics with gray-scale colors. Graphics designed for simplicity and situational awareness ensure abnormal situations can be addressed properly. When an event occurs where operator attention is required, the graphic would highlight that change and drive operator attention to it.
Studies suggest that response time to abnormal conditions can be reduced by an estimated 10%with the implementation of a standard user environment designed to ISA 101.
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Next, let's address alarms.
By definition, an alarm is a visual and/or audible signal indicating an occurrence of an abnormal condition that requires an operator action.
Alarms are displayed in the HMI on a graphic referred to as an Alarm Summary display. Within this Summary, operators can interact with the alarms to validate and initiate remediation as necessary.
ISA 18.2 standards define types and guidelines for alarm interactions, such as acknowledging, suppressing, silencing, and shelving, just to name a few.
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The ability to store and display live data values throughout a manufacturing process is an essential function of any graphical HMI.
Trending is the ability to display and compare values, graphically. An HMI trend configured to read and display these values directly from the controller is referred to as a real-time trend.
Data logging is the ability to periodically store key values during production for evaluation or validation at a later time. An HMI trend configured to read and display these values from the storage location of a data log fileis referred to as a historical trend.
Recipes are sets of related data parameters and values used to make a product.
Examples of these could be oven temperatures or cook times. They may also include ingredients, such as milk, eggs, or sugar along with necessary quantities or weight measurements.
The management of recipes range from storage within the controller for the simplest ones, to large databases for the more complex. The ability to manage recipes from within an HMI is, however, one of the most common methods. Most HMI-based recipe tools allow users to view, select, modify, activate, and save recipes directly from within a running application.
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The ability to sell and compete globally is becoming increasingly important to both machine builders as well as end-user manufacturers.
With multi-language support, HMI applications developed in one language can be easily translated into other languages to support localized manufacturing.
In addition, many systems allow operators to actively switch between the different languages right within a running application, a feature referred to as runtime language switching.
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The typical machine-level operator interface is a dedicated terminal and a self-contained unit. In most cases, it is the closed system we talked about earlier.
The typical application contains 20-50 displays, 50-200 alarm messages, and up to 100 data log elements.
For larger applications, the HMI tends to be an open system. In other words, it runs on a standard Windows computer to provide users with more flexibility in software options.
Some customers still refer to these systems as Supervisory Control And Data Acquisition, or SCADA for short.
A typical SCADA system requires more than 100 displays, more than 500 alarms, over 1000 datalog elements, and perhaps additional software tools and databases.
Site-level HMIs can either be deployed on the plant floor, as standalone systems running onindustrially-rated computers, or a distributed system that is commonly used in plant controlrooms.
A standalone system, sometimes referred to as a "station", is one in which all components of the HMI run on the same computer. These types of applications are commonly deployed on the plant floor.
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Most HMI system vendors choose to separate the software components based on their function. This multiple-computer, server/client architecture is referred to as a distributed HMI and is highly flexible.
Running the components on multiple computers enables optimal scalability up to the customer's current and future needs while the overall system is managed as a single application.
In this example, the servers are responsible for providing (or serving) the information which is being requested. This is where most of the processing, in a sense, the workload of the system, takes place.
The clients represent the operator/engineering interface through which served data can beviewed on a screen.
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This configuration allows the use of single or multiple servers with multiple clients, rather than many individual stations, for convenient centralized administration of the HMI application. Since more resources can be added later, it has the flexibility to grow as needed.
High Availability options, implemented initially or at a later time, minimize data loss and downtime,and disruptions to clients if any of the servers fail.
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After reading this post, you should be able to;