Some automation vendors offer direct access to machine HMIs and OITs with iPhone apps. Apps are useful for personal purposes, particularly for quick access to online info. We're wondering if app access for machine operator interface is better than browser-based access through a smartphone, or just a sexier marketing of the same capability.
—From March '12 Control Design
Apps Faster, With More Features
When deciding whether an app is better than browser-based access via a smartphone, the inevitable question is: "Why would I want to pay for an app when I can get browser-based access for free?" One significant reason is that browser-based access usually provides only read-only information, whereas an app generally provides two-way access that can allow a user to control a machine via a smartphone.
An app also provides information much faster, unlike browser-based access, which requires the entire page, including graphics and headers, to be downloaded before the information can be accessed. This enables users to access the information and respond faster, making real-time monitoring and control feasible.
One of our customers, Joel Froese, owner/operator of the Red Bank Hydro Plant in Columbia, S.C., prefers an app for the control of the machinery at his hydroelectric plant from his iPhone via the onscreen buttons. As he notes in the recent Control Design article "Remote Access Makes New Connections," he can now start up and shut down the system just as if he were standing in front of the HMI. "And built-in safety features ensure that I don't accidentally push the wrong button."
Another customer is Mark Gentry, an engineer with Samuel Jackson, an OEM that builds moisture control products for drying and moisture restoration systems. He was also quoted as saying that he prefers an app to a web browser in the Control Design article "Remote Access Down on the Farm." He explains that using a browser on a mobile device means waiting for a page to load, including all the headers, graphics and other overhead that entails. "With an app, the only thing you need to pull is the data itself, which, in most cases, doesn't amount to very many bytes."
Furthermore, some apps are actually very inexpensive, making the decision to choose app over web browser that much more straightforward.
product manager HMI/communications,
Features, Features, Features
There is no denying the smartphone and tablet market proliferation. iPhones, iPads and Android devices are sexy. Why not just use the built-in web browser for everything?!? Simply put: Features.
Natively developed apps can be tailored specifically to the device and offer access to features that a web page just can't duplicate. For example, a natively built iOS app can run in the background waiting for data to be pushed or pulled from a cloud-based web service. While accessing the data for an automation application, the app could keep a local database of trends and information without needing to be online at all times.
A native app also can provide a much more familiar look and feel with gestures and other input options not available in a traditional web-page model. The multimedia experience can enhance the HMI framework to be much more than the simple toggle switches and gauges of today.
Imagine a situation where you have a machine HMI without Internet access available. An app-based HMI could communicate with the automation controller, offer control functions, and gather logs and other useful statistical information. The next time that the user's mobile device is online, it could "phone home" and provide tracking and statistical information to a server running in the cloud.
Sexier marketing? Absolutely—but nowhere near the same capability. Native features make all the difference.