Introduction

Many industrial automation applications rely upon custom or off-the-shelf software installed on individual computers to allow for interactivity between an operator and the machinery on the floor. While most of these applications perform their functions well, they all have a nagging (and sometimes serious) limitation: An operator must be at the computer in order to interact with the application.

As technology has evolved, engineers and system integrators have been able to start utilizing the technologies that have made use of the Internet a part of our everyday lives. These features include the remote viewing of data without having to physically be at the computer on the factory floor. 

Keep in mind that just because you are using technologies used on the Internet, it does NOT mean you are putting your plant information out on the public Internet.  Web browsers and the many technologies used with them work perfectly well inside the company firewall, on a private secure network, and over remote access technologies such as Virtual Private Networks (VPNs). We certainly are not advocating “throwing open the doors” to expose your plant information anywhere. 

What we are suggesting is that you take a good look at how the use of browser technologies of today eliminate the need for client side software installation, thereby reducing your total cost of ownership.

In this paper, we’ll give you an introduction to a technology known by the acronym of AJAX that promises complete interactivity with your factory floor not matter whether you are on a local intranet or on a private secure connection from far away.  This paper is an overview and introduction to the technology.  We do have webcasts available that get into more of the details.

What is AJAX?

AJAX stands for “Asynchronous JavaScript and XML”. It’s nothing more than big words that means your web browser can ask a Web Server for information, go off and do other things, then receive the data from the Web Server when that data is ready to go.

In the past, a Web Browser would ask a Web Server for a page via a URL (like http://www.softwaretoolbox.com). The Web Server would compose the page and send it back to the Web Browser for display. And then…that’s it. The page was nothing more than static information. If you wanted to update your web page, you hit the “Refresh” button, and the Web Server would send back the entire page.

However, AJAX use special JavaScript (a special “scripting” language that comes with most web browsers) commands to send requests to the Web Server for pieces of information. Your browser will then go off and do other things until the Web Server sends back an answer, at which time the JavaScript processes it. This gives the appearance of your browser changing data on the screen without having to ask for the entire page from the Web Server. 

Click to See An Example of Ajax Live!

What is the advantage to AJAX?

Actually, AJAX and its capabilities have been around for years. But as with all technology, someone has to put two and two together before the world can reap the benefits.

All else being equal, the biggest advantage to AJAX is the speed and lower bandwidth usage.

Let’s take a look at an example:

Let’s say you had a table of pressures from various boilers. This information can be seen on a web page by requesting it from a Web Server, and this page returns 50,000 bytes of data. In addition, you know the data value update on the boilers once every second, although only a few at a time will actually change.

Without AJAX, you will have to manually hit the “Refresh” button to reload information, thus send upwards to 50,000 bytes from the Web Server to your browser each time. In addition, if the data changes once a second, you are obviously going to miss some data.

With AJAX, your page can have AJAX request data from the Web Server once per second, and request only that data which has changed. Once the data comes back, only those areas on the screen are updated. The result is a clean, dynamic system that allows you to monitor your boilers even 3000 miles away, once per second, and only using the bandwidth required to send a few data changes.

How is AJAX Revolutionary?

Ok, so AJAX can save in speed and bandwidth. It also can save in development cost.

For example, here is a typical factory network that has three control stations and one reporting station:

One application runs all three of the operator consoles plus the reporting console. Any updates to that application will mean applying the update to all computers, meaning four separate updates.

If one of the computers needed to be replaced, then the application will have to be installed on that computer and tested to insure that it works. (see image above)

With an AJAX web application, should you ever need to update the application on the client computers, it will only need to be updated on the Web Server. Once rolled out there, the four computers, which only have Web Browsers installed, will immediately see the update.

And if one of the computers needs to be replace? All that computer needs is a Web Browser and your done.

And let’s take it one step further: Suppose you had 100 corporate bosses who wanted to monitor the site. Assuming you had your Web Server secured against intruders, your one application can be made available instantly not only to your local computer, but to any computer any where in the world assuming the person has the rights to gain access to the Web Server.

The Potential is Enormous

Of course, Web applications have limits. But technology like AJAX and Web Services are quickly bridging the gap between merely showing data in a Web Browser and giving operator full control of their industrial automation systems.

Try it own your own computer

It only takes a few minutes to Download the OPC DataHub and install it on your computer and you can see AJAX in action to see why an AJAX-enabled Web Application is the wave of the future.  No webserver required!  Click for simple installation instructions.

Trying out the demo doesn’t require you to expose anything to the internet and even comes with a simulated data source.  If you’re interested in the security options in the demo, the OPC DataHub web server includes the ability to use password protection and SSL encryption to provide data security.

Have Questions? Want to Learn More?

Consider watching one of our webinar recordings on OPC to the Web.

Attend our live Webcast on Friday 25 July 2008 at 11:00 AM EDT (GMT-4):
How to View Production Data in Web Browsers using OPC DataHub

Or feel free to call us on 1-888-665-3678 or +1 704 849 2773.