FEATURE HMIS, PLCS & INDUSTRIAL PCS
Selecting an HMI with the right features can greatly simplify the
creation and support of IoT applications, empowering users to
interact with sensor and edge device data from anywhere in the world
via smartphones, tablets and PCs. Marcia R. Gadbois, general
manager and VP for the Wonderware InduSoft Web Studio group of Schneider Electric comments
he Internet of Things (IoT) starts with connecting sensors and other edge devices, such as motor controllers, to HMIs. These connections are typically made in one of two ways: with a controller such as a PLC, which is then connected to a Human Machine Interface (HMI) platform; or directly by the HMI platform. In the first case, the HMI can be
T
PC-based, or it can be hosted on an embedded operating system platform such as Windows Embedded or Linux. In the second, the HMI would typically be a PC with data acquisition cards installed. Either way, the HMI application is developed on a PC, and then downloaded to the target runtime platform, either another PC or an embedded platform. Efficiently connecting the HMI to sensors and edge devices, and then to end users, requires: • A wide range of drivers • Support for multiple connection protocols
• Configure devices at run time • Small footprint • Simple remote visualization • Single development environment • Support for multiple target runtime platforms
• Direct database connectivity
DATA COLLECTION To make connections with a wide variety of edge devices and controllers, the HMI must be able to support hundreds of communication drivers. In addition, it should provide support for popular
16 SEPTEMBER 2016 | DESIGN SOLUTIONS
GET CONNECTED with the right HMI
industrial communication protocols such as OPC Unified Architecture and XML-DA. An interesting new driver – which is
suitable for the Internet and IoT applications – is Message Queuing Telemetry Transport (MQTT). This is a connection protocol for the IoT using a publish-and- subscribe communication method. It is an extremely simple and lightweight message protocol, designed to connect low bandwidth devices. As an example, a device or controller could subscribe to a certain alarm or piece of information, and this will be the only data it receives. Another key feature is the
“To make connections with a wide
variety of cutting edge devices and controllers, the HMI must be able to support hundreds of communication drivers. In addition, it should provide
ability to configure devices at run time. With the number of new devices entering the IoT world, this feature should be built into the HMI software so changes can be made to the HMI’s screens, functions or connection without stopping the machine.
support for popular industrial communication protocols”
provided with an embedded HMI and no local display, and it could be connected to the Internet through its Ethernet port. Remote visualization via a smartphone or tablet connected to the Internet could be used for a variety of purposes such as monitoring of operation and troubleshooting. Remote information functionality could provide filled bag weights to an ERP application. Remote visualization is made easier when the HMI supports a
variety of remote devices with features such as
automatically resizing screens depending on the
device. For example, a screen could
be developed once, and then displayed without additional programming on a large PC-based display, and on a smaller smartphone or tablet display. The HMI should be deployable on
multiple target runtime platforms, with all runtime applications created on a single PC-based development environment. The right HMI can deploy not only to Microsoft Windows or Server operating systems, but also to Microsoft Windows Embedded Compact, Standard, Handheld or Automotive as well. Linux and VxWorks are two other operating systems popular in many embedded devices.
ENABLING EMBEDDED APPLICATIONS A small footprint for the HMI software, less than about 5MB, is important because it allows the HMI runtime to be hosted on a variety of platforms in addition to a PC. These platforms are less expensive, more compact and easier to support – particularly in applications where no local display is required. A small footprint HMI running on an embedded HMI helps create simple remote visualization and information solutions, a big part of the IoT. For example, an automated bag filler at the end of a production line could be
An important feature for IoT applications is the ability to configure display screens once, and then deploy them to a variety of devices such as smartphones, tablets and PCs [image courtesy of InduSoft and AutomationDirect]
EFFICIENT DATA TRANSFER If every smart device connected to an HMI is transmitting all of its collected data, IoT system resources such as network bandwidth and database capacity can be quickly overloaded. The HMI must therefore consider how collected data is transmitted and stored. Many IoT applications utilise the
cloud for data storage, so the HMI should support direct connectivity with cloud-based databases via MQTT and other newer protocols. Older HMIs are often limited to older protocols such as ODBC or ADO, which are very inefficient for transmitting data from an HMI to the cloud.
InduSoft
www.indusoft.com
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