Authored by:
Leland Teschler
Editor
leland.teschler@penton.com
Key points:
• Control systems can communicate with mobile devices either through a mobile-enabled Web site or through an app designed to communicate directly with the controls.
• If response time is important, apps can be a better bet than a mobile-enabled Web site.
Resources:
InduSoft Inc., (512) 349-0334
iRule LLC, (313) 227-6136
Omron Industrial Automation, (800) 556-6766
Opto 22, (800) 321-6786
ProSoft Technology Inc., (661) 716-5100

People lucky enough to hitch a ride on a Gulfstream G550 private jet outfitted by industrial designer Stefan Radev find the plane is equipped with iPads. But the iPads aren’t for reading ebooks or playing games. They actually control the passenger-compartment climate and entertainment systems.

Radev’s luxury jet exemplifies a trend in mobile platforms: smartphones and tablets increasingly are taking on roles as data displays and even operator terminals. And they aren’t just managing consumer goods. Several controls makers let mobile platforms work with the controls running industrial processes.

There are two different ways of letting smartphones or tablets communicate with controls: by devising a downloadable app that communicates with the control network, or by creating a mobile-enabled Web site that provides information about the control system. When the scheme involves a mobile-enabled Web site, the smartphone or tablet functions as a thin client, mainly serving as a display device and relying on the Web site for most number crunching of data. But in some cases, a mobile-enabled Web site won’t provide the kind of performance an application demands.

That was the case for iRule LLC, Farmington Hills, Mich., makers of an iPhone app that lets the phone function as a universal remote control for home theaters and audio/visual equipment. “We did tests and found that the Web added at least 250 msec of delay when you punched a button,” explains Itai Ben-Gal, iRule CEO and cofounder. “It was noticeable among people who have picked up a remote to change a volume for 30 years.”

iRule’s universal remote app communicates with AV equipment through a gateway device which typically learns the control protocols of individual remotes by sensing the data on their IR beams. The gateway, in turn, hooks up to a Wi-Fi connection to communicate with the iPhone. But iRule’s app can also work with home-automation systems, even when out of range of the home Wi-Fi. In this case, the phone uses a 3G data network from a cellular carrier to make a mobile virtual private-network (VPN) connection to the gateway. The VPN provides a level of security and lets the phone user roam across networks without losing a connection to the home-automation system.

A point to note for anyone with thoughts of devising a control app is that iPhone apps don’t work on non-Apple platforms. The iPhone app-development language is one called Objective C whereas Android apps are created using the Java language. That often means a total rewrite of the app to make the jump from the iPhone to Android. In the case of iRule, Ben-Gal says the Android version took two months of work from two full-time programmers.

“That is a lot of time to just duplicate something you have already done,” he laments. “The reason for the time requirement is the nature of the Android. For example, there is one screen size for the iPhone and one size for the iPad, but there are six or seven screen sizes on the Android. We wanted to encompass as many of those devices as possible and not leave anyone behind.”

Another factor that can eat up development time for a control app is the interface to the controls themselves. For example, consider an iPhone app called i-View from ProSoft Technology Inc., Bakersfield, Calif. ProSoft makes communication-interface modules for some 60 different industrial protocols. Its typical interfaces are to motor controls, drives, and other devices in machinery, packaging, and production uses. The operator of the i-View app can view and change live PAC/PLC variables (tags) as well as compute trends and graph live tag values over 1, 2, and 10-min intervals. The i-View app displays the values in lists and includes user-established variance allowances with alarms, including local notifications. Controls and data displays can be color coded based on the value of readings.

“It would be nearly impossible for an ordinary Apple developer pulled off the street to develop something like this,” says ProSoft technical services manager Chris Hines. “The GUI is the easy part of developing the app. The hardest part is the control protocol. The guy who did our app is a controls engineer who knows the Rockwell Automation, Milwaukee, platform very well. It took him about eight months to do it.”

To get the control data to the phone, the plant facility must be on either an Ethernet/IP and/or Modbus TCP/IP network and must set up a wireless 802.11 (Wi-Fi) and/or cellular network connection. The i-View app has built-in Ethernet/IP and Modbus TCP/IP drivers and talks to the PLC on the control system directly. The Ethernet/IP drivers support ControlLogix, CompactLogix, and Micrologix, SLC, PLC5, and similar Rockwell Automation PLCs. Hines says Prosoft also recently added control protocols for Siemens networks.

Another controls maker offering iPhone access is Opto 22, Temecula, Calif. Its iPAC app lets users monitor and control Opto 22 Snap I/O points and PAC control variables, tables, and charts from an iPhone or iPad. The iPhone accesses the network either through Wi-Fi or a cellular link. Security in this case comes from the password protection on the local network. Once connected to the control network, the app automatically discovers the Opto 22 devices and provides information about each one, such as its IP address and the control strategy it is currently running.

Opto’s iPAC app is primarily intended to provide a window into I/O point status but it also lets users change values or turn outputs on or off. Its main purpose is in commissioning, debugging, and responding to alarms. Specifically, iPAC users can see digital point status, turn digital outputs on or off, view analog point values, write values to analog outputs, view and change control variables, table elements, charts, I/O.

Opto 22 developers say it took two of them about two months to develop the basic iPAC app, and another few months to get through tweaking the user interface and preparing the materials needed for certification and approval by Apple. They are also working on an Android version.

Mobile sites
Of course, you don’t necessarily need to build an app if the goal is to give smartphones access to controls networks. Some controls makers take the other approach of building a mobile-enabled Web site on a server that connects to the control network. Then smartphones and tablets can get a look at the control network merely by examining the Web page — no app building required. The advantage of this approach is that such a mobile-enabled Web site would allow access from both Androids and iPhones. One disadvantage is the necessity for configuring a Web server that hooks up to the control network.

In Opto 22’s case, the company says it went with a mobile app as opposed to a mobile Web site because it wanted to develop a zero-configuration, no-server-required setup. Opto’s iPAC does not need to connect to a server for monitoring or control or to access data. It can communicate directly with the source of the data — the Snap PAC controller and/or the I/O. Opto 22 does, however, plan to offer a mobile Web-site version of its iPAC capabilities relatively soon.

The advent of a new Web-language development standard called HTML5 could make server-based control access more attractive for mobile devices. Though it is still under development, HTML5’s core aims are to improve the language with support for the latest multimedia schemes such as those for video and audio. These capabilities should make it easier for developers to configure Web pages for control systems that provide the same sort of high-level functions available on apps.

Several firms have already developed Web-based control interfaces even without waiting for the advanced functions of HTML5. An example comes from InduSoft Inc., Austin, which has a platform for developing Web interfaces for control systems. Users put a runtime version of the software, called InduSoft Web Studio, on an application server. This generates the Web pages that contain tags and similar information viewed on the mobile device. Mobile devices that connect to the server, in turn, are thin clients that get most of their data from the server.

The embodiment of IWS that produces smartphone and mobile platform sites is called the Studio Mobile Access (SMA). Users can deploy SMA to devise a site that lets phone users view and interact with tags and alarms remotely. InduSoft says the software can typically handle hundreds of tags with no problem. The resulting smartphone Web pages use mostly text to promote interaction speed. SMA can work on not just Android and iPhones but also Web-enabled phones that are not considered smartphones.

InduSoft says it has developed systems based on SMA for controls from vendors that include Beckhoff Automation LLC, Burnsville, Minn., and Omron Industrial Automation, Schaumburg, Ill.

© 2011 Penton Media, Inc.