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What does mobile means for measurements?

30 July 2013

Gartner estimates that 1.2 billion smartphones and tablets will be purchased in 2013. What does this mean for industrial measurement and control applications? Are portable measurement devices and industrial HMIs also on the path to obsolescence? Kyle Voosen, marketing director at National Instruments UK & Ireland, tackles these questions.

Because of their network connectivity, smartphones and tablets are great tools for remotely viewing measurements. However, their small size and processing power also make them effective for taking portable measurements. For portable measurements today, engineers can choose from several options, such as handheld meters and portable data loggers with integrated displays. Typically, however, these have fixed functionally that is defined by the vendor. Smartphones and tablets can offer a more flexible solution and many engineers are already beginning to directly connect them to data acquisition (DAQ) devices and write software specifically for their application needs.

This idea of tethering a DAQ device to an off-the-shelf computing device is not a new concept for portable measurements. Previous attempts, such as miniature laptops, used conventional power-hungry processors and therefore provided unusable short battery life. Personal digital assistants (PDAs) offered longer battery life and were useful for some applications, but their underpowered processors limited their functionality.

Today’s smartphones and tablets now pack more processing power than the standard desktop PCs of a few years ago and can be used to write more powerful processing routines for inline analysis directly on the device. The processors consume less power than standard PC processors so the devices are useful for longer periods of time. They include gigabytes of data storage, providing ample room to save logged data. Touch-screen technology offers an intuitive way of interacting with the user interface, which can be designed to mimic application-specific knobs, buttons and controls. The features in mobile computing devices have evolved to create a viable platform for portable measurements that match or exceed some of the capabilities of traditional methods.

Portable biomedical applications exemplify the need for this additional functionality. Paramedics and first responders use portable tools to diagnose patients’ conditions. These devices must be small enough to deploy to ambulances and medical evacuation helicopters, but powerful enough to perform the processing required for diagnostics and intelligent feedback. This is extremely important in time-critical applications with limited diagnostic resources, such as in military and emergency medical environments. Off-the-shelf computing technologies, like smartphones and tablets, help create more powerful, portable medical devices at lower costs.

Beyond tethering a DAQ device to a smartphone or tablet, wireless measurement devices offer another effective solution for handheld measurements. This enables one mobile device to take a measurement from many wireless measurement devices. Native apps or software interactive development environments (IDEs) can be used to program these wireless measurement devices. As measurement systems increasingly need more flexibility, engineers can expect that measurement device manufacturers will release more wireless measurement devices.

Portable HMIs
The days of providing a fixed HMI or panel PC for every device and machine could be numbered, as operators, engineers and managers begin to carry tablets that can interact with multiple systems at the right level of access. When integrating portable HMIs into a measurement or control system, one of the first considerations should be how the devices will communicate with each other. Standard network protocols such as TCP or UDP can be used over wireless, but a growing trend is to use a technology built on TCP and HTTP called web services. A web service is an application programming interface (API) that can be accessed via HTTP requests. When called, web services return a human-readable response. Modern web services use JSON responses, but other response options are XML, HTML, or plain text. Engineers can then program effective interfaces that render the web service response as something more visually insightful, such as waveform graphs showing yields or temperatures mapped over a system diagram.

There are several reasons why engineers and IT departments are choosing web services over other communication technologies. Firstly, web services are straightforward and simple to access from any programming language, including C++, Objective C and LabVIEW. Secondly, since web services sit on top of common network protocols, the communication is considered ‘IT friendly’ compared with proprietary network protocols. Thirdly, web services can also be easily encrypted via industry-standard technologies like Secure Sockets Layer (SSL) or Transport Layer Security (TLS).

Another consideration is how to view or consume data communicated from industrial systems. Many different technologies can be used to create a data client, which is the GUI that permits someone to view or control the data being transmitted from the system. A standard web browser can send HTTP requests to the web service. Using HTML and JavaScript, a data client can be created to view the returned data on a graph instead of just XML. Building a custom data client that uses a web browser provides the flexibility to customise the look and functionality while using technologies that do not require an extra run-time engine to operate. HTML is also cross-platform compatible, so one data client can be created to work on multiple operating systems. Another alternative to HTML is to create native apps that run on specific mobile operating systems.

Native apps provide better performance and usability when compared to web-based (HTML) apps. A caveat is that native apps need custom development for each mobile operating system. Apps written for Android, for example, will often need to be ported to iOS. HTML5 is promising because it works with most operating systems, but the technology is still quite young. Notably, Facebook switched from an HTML5 app back to native apps after performance and usability complaints were heaped on its HTML5 app. HTML5 is quickly improving performance on mobile operating systems, so the technology will probably be a more viable option in the near future.

The first step to create a remote HMI for an industrial system is choosing how to communicate data wirelessly and selecting which data client technology to standardise on. Engineers are learning more about the options for creating remote HMI solutions, making this functionality a primary consideration in measurement system platform choice.

Data integrity and system security
The more mobile devices that are used to connect to secure information, such as bank accounts or private company data, the more they become the target of hackers. Attacks by malware, software aimed at disrupting computer operations, have risen exponentially over the past few years in mobile operating systems. Symantec, a global security software company, listed ‘mobile attacks’ as one of its top five trends to watch out for in 2013. As engineers are adding mobile technology to their industrial systems, mobile security must be a primary concern.

Common ways to combat mobile security threats are to download apps only from official app stores and use antivirus software apps on mobile devices. Engineers should look into the specific security details for their mobile devices and add necessary security measures. Simple steps such as requiring a login or pin code and turning on ‘remote wipe’ services to erase all information on a device if it gets stolen or lost can help mitigate some risks.

The rise of enterprise app stores will also assist in mobile security in the workplace. Mobile operating system providers now make it possible for companies to create their own internal app stores with company-approved apps. This is a good way for IT departments to distribute apps that access company databases as well as push suggested mobile apps like antivirus protection.

A mobile future in measurement and control
Although industrial measurement and control system designers are generally conservative when it comes to adopting new technologies, the ubiquity and obvious benefits of smartphones and tablets foretell a quick adoption timeline. Looking beyond handheld measurements and portable HMI, future industrial measurement and control systems will continue to evolve into a more networked state, where mobile access is a primary requirement. In these systems, mobile technology will become core components to acquire, analyse, log and present data.

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