Compact HMI software can be integrated into near-edge devices to add IIoT connectivity and other functions.
Scott Kortier, InduSoft Web Studio Senior Technical Engineer at Wonderware by Schneider Electric
Machine builders and OEMs often provide human machine interface (HMI) functions with a separate component, either a PC-based HMI or an embedded HMI. In either case, the HMI program is developed on a PC and a runtime project is downloaded to the target.
The term PC-based HMI means an HMI software runtime application hosted on a PC, which is the target. The term embedded HMI refers to an HMI software runtime application hosted on a target platform capable of running an embedded OS such as Windows Embedded, Linux, VxWorks, and so on.
But a new class of embedded HMI is emerging, where a compact HMI runtime is hosted on a target smart edge device such as a smart drive, power meter, special-purpose controller or another component—and viewed on a smartphone or tablet (Figure1). In this case, the HMI runtime is still developed on a PC, but in this case, the target is the smart edge device. Using off-the-shelf configuration software, (such as IoTView), only the HMI functions and data collection required for the device is transferred to the target as the runtime application.
For example, some smart edge devices will only require HMI connectivity functions, while others may need connectivity, local data storage and visualization. Customizing the HMI application to the target allows the developer to control and limit the computing resources required at the target, which is critical as most smart edge devices have limited storage space and processing power.
In some instances, embedding HMI functions in one or more smart edge devices will eliminate the need for a traditional PC-based HMI or embedded HMI. But in other cases, a traditional HMI will work hand-in-hand with smart edge device HMIs.
An HMI/SCADA software package, whether hosted on a PC or an embedded platform, traditionally provides the connection between the plant floor or facility and the Industrial Internet of Things (IIoT). It’s the means or gateway for connecting controllers and smart edge devices to other SCADA systems, company databases, ERP and MES systems, the cloud and the IIoT.
Embedding the HMI at the edge
Some smart edge devices have embedded connectivity that could, in theory, push data directly to the cloud, but it’s typically not feasible in most industrial systems for security and other reasons. However, modern, platform-agnostic HMI software enables embedded connectivity gateway applications to be developed on a PC and downloaded to the smart device. Such gateways can then establish connectivity between smart devices and cloud-based systems such as database and analytical applications.
The embedded smart device HMI delivers connectivity by consolidating, filtering and manipulating the information through configurable scripts and rules before forwarding it to the cloud. Moreover, built-in security settings and native support for encryption (SSL) represent an additional layer of security and isolation between the real-time control network and the enterprise network and the internet.
The smart edge device typically has a serial or an Ethernet port, or a wireless connection. The device may also include a TCP/IP stack. Local or remote users can connect to the smart device—through Wi-Fi for example—using a smartphone, tablet, laptop or another component capable of hosting a HTML5 web browser. Given proper credentials, the user can monitor or adjust the system settings through a configurable rich graphical interface—providing visualization into the smart edge’s embedded HMI.
The embedded connectivity at the smart edge device eliminates custom coding of communication drivers and related support of firmware. It also eliminates the need to use custom code to create displays because extensive object libraries and built-in graphical functions are available.
One of the main advantages of embedding HMI at a smart edge device is the ability to send data directly to the cloud, a necessity for many IIoT implementations. Sending data to a cloud-based storage system such as an SQL database—or to a commercial data-storage company such as Amazon, Microsoft Azure or Alphabet—is simplified.
Future proofing connectivity
Eventually, every device or system will eventually be connected to one another through vertical and horizontal networks to get the most productivity and value from each machine. The scope and speed of which devices are connected are proceeding quickly, so design systems need flexible architectures that can keep pace with shifting standards and communication protocols.
One way to protect the investment and make current HMI systems future-proof is to design solutions based on off-the-shelf products and open architectures. Key features to look for include:
–portability to different target platforms (Windows, Linux, for example)
–interoperability with multiple protocols and systems (driver, OPC, Databases, and so on),
–support for mobility standards such as HTML5 to access the information from devices such as smartphones, tablets or wearable devices.
One example is an IIoT agricultural implementation that deploys intelligent irrigation systems. Adequate water supply is key for agriculture. Integration of Web Map Service and Sensor Observation Service with the intelligent irrigation system provides a way to manage use. This IIoT agricultural implementation analyses water requirements and weather forecasts to provide only the irrigation needed, reducing water and energy use.
Another example is PML Exploration Services, an oil field services company. PML offers real-time information to ensure affordable, efficient and safe drilling practices. The HMI/ SCADA system pushes data on gas and soil composition to the cloud, even in remote locations off the grid, and notifies users of alarms and critical conditions. These notifications can be used to improve operations and safety while protecting expensive drilling equipment.
Embedding HMI connectivity in smart edge devices simplifies communication locally and with the IIoT. It also makes it easier to create advanced operator interface displays and to exchange data with cloud applications and other computer platforms. Instead of custom code, off-the-shelf software is available to develop and configure the embedded HMI functionality and download it to the smart edge devices.