Process Control: Making The PLC Internet-Ready
August 1, 2003 By Pulp & Paper Canada
Is it just more Internet hype or is there some reality behind the idea of web-enabled automation? Is it possible to connect production and processing machinery by their PLCs to the Internet? More rele…
Is it just more Internet hype or is there some reality behind the idea of web-enabled automation? Is it possible to connect production and processing machinery by their PLCs to the Internet? More relevant — is it practical or profitable?
THE SHORT ANSWERS
First, Internet access can provide compelling competitive advantages for linking manufacturers with service technicians, customers, suppliers and subcontractors.
Second, proven affordable technologies are readily available to connect any PLC, machine control or I/O to the Internet and intranets.
Third, machine-to-Internet access has the potential to become a standard utility, a make/break for doing business.
Following is a short course on the what, why and how of getting web-enabled.
WHAT IT IS
Web-enabling gives real time access to data and control virtually anytime and from anywhere it’s required. It uses communication with any manufacturer’s PLC or I/O to send information via the Internet to anywhere in the world. Unlike the “horizontal” integration of standard B2B and B2C implementations, web-enabled automation drives real-time accessibility “vertically” down to the level where things are actually produced, ordered, tested, and stocked.
This access to individual machines gives producers, their customers and suppliers shared, front-line, real-time intelligence to optimize production control and coordination, while enhancing flexibility and response time.
WHAT IT DOES
Such accessibility and connectivity can do lots of good things in better controlling production. Some examples:
Check production data on a critical process, machine or order in real time, without waiting on batch reports.
Track run time through the machine control and automatically request tool replacement, machine maintenance, etc.
Have the system notify a technician via e-mail when it needs help. Communicate directly with machine maker to avoid delay and cost for a service rep visit.
Collect data on part parameters and production (from machine controller or independent sensor I/O) and send it to a server PC to do statistical process control (SPC) using standard PC-based software.
Access HTML help files with graphics and instructions.
Collect data from many distributed machines or processes and adjust activity to achieve adaptive, closed-loop, optimized production.
Monitor and control remote operations (such as pumping station or power distribution system) to reduce field staffing and travel.
Link a system in real-time to customers and suppliers, and adjust production flow, restocking, shipping, etc. to customer demand data.
Beyond the internal advantages or benefits, two outside factors may drive the need to become web-enabled:
First, customers are coming to expect “real-time” deliveries of product and information. As individual consumers, we are experiencing on-line ordering, status checking, and next day or same day deliveries of merchandise. We want the same for our business.
Second, if your business can’t meet such expectations, the competition will. And, once they have implemented web-enabled automation successfully, they’ll be able to satisfy the customer more quickly and at lower cost than non-web-enabled companies.
What pieces and parts are required to get web-enabled? The basic parts required for real-time, web-based data access and control are:
An interface to the machine/process/ building/”thing” to be monitored and controlled via the web (network) connection. This Internet connection can be made by a standard hardwired Ethernet line, a modem/phone line (dial-up) or a wireless modem.
A web server (or “thin server” data service) to make the desired displays and /or web pages available to the remote browser.
A data service or interface to handle data exchange between the local “thing” (server) and the remote system (client). A common “language” is required. XML (Extensible Markup Language), the standard defined by the World Wide Web Consortium, exchanges data along with a “tag” that defines the data. This makes XML independent of the sender’s and receiver’s hardware platforms, OS, and application, which is a powerful and critical advantage when implementing open systems within a company or between different companies, as in B2B applications.
Browser interface — For remote viewing of data and/or web pages, the only requirement is a standard browser interface (which can be a desktop, laptop, PDA or “thin client”). Applications requiring exchange of real-time data (SPC, optimization, or enterprise software) need a remote server PC and a compatible data exchange service.
In simplified block diagram, the parts might look like this (see Figure 1).
Web-enabling doesn’t mean that you need to replace your present machine or process controller, nor invest in an industrial PC for your browser interface. A new breed of “thin” web devices can fill the role in many applications. They combine ruggedness with low cost by providing only the functionality required.
A thin server (as an example, WebLink from Advantech), is a complete “intelligent embedded server” solution. Providing all hardware and runtime software needed to web-enable a system, it connects to the machine/process controller or other control device (I/O, sensor, etc.) using a standard RS-232/485 serial port or a fieldbus adapter. A network connection is then made through WebLink’s standard Ethernet 10/100Base T port or via optional modem or wireless network/Internet connections. Development software enables web pages to be easily created and data connections made to remote application software, then maintained from anywhere via the network connection. Security is provided by WebLink through password-protected user login (and optional restricted access by the user Internet Provider).
A thin client serves the role of browser PC to access a web page/data display resident in the thin server. If only required to view web pages, the thin server can be a dedicated design and very simple device requiring only an LCD, CPU and a small amount of memory. No software is required other than Internet Explorer or Netscape, since the web page is resident in the thin server. In the same way, the thin client can view web pages from any source accessible via the network.
Control makers may also provide other elements designed specifically for web integration, such as operator interface terminals and HMI software. All technologies are readily available for creation of robust, cost-effective, open solutions to web-enabled automation.
Web-enabled automation is a practical reality. It provides real benefits and real competitive advantages for business enterprises. It closes the loop with customers and suppliers to optimize production flexibility and cost competitiveness.
For more information, contact: Advantech Industrial Automation, www.advantech.com.#text2#
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