Control Engineering HMI eNewsletter for November/December 2000
In this issue:
- What is HMI?
- Results of survey working with IT departments
- Operator workstation reliability
- Thin Clients
- In Control Engineering November
- Products to watch
What is HMI?
Human-machine interface perhaps should be called 'automation interface' or 'enterprise-machine' interface. Push buttons and pilot lights were the original means for operators to communicate with machinery. Graphic terminals provided a better view of what was happening in the machinery. As PCs became less expensive and more reliable, SCADA software could move from larger UNIX platforms and find uses in smaller applications. Advances in both computer and display hardware as well as software continue to propel HMI to an ever more important role in the new manufacturing enterprise. It is the central nervous system providing information for everyone from technician and engineer keeping the machines running to corporate software systems for customer and supply chain management.
Results of survey working with IT departments
In my last newsletter, I referred to some personal experience I had in my old systems integrator/sales engineer days. There were a couple of major projects where the IT department worked closely with control engineers installing some factory critical, real-time information systems. I wondered how many of you found working with IT to be a challenge or whether things were changing.
The typical response was that it was still a challenge for control engineers to work with IT people. One response pointed out that typical IT people are software-oriented almost to the point of ignoring hardware. A control engineer ignores hardware only at great peril! Where we tend to think often in 'bits,' IT people tend to look at 'bytes' or 'words.' They can't understand why we could concern ourselves with toggling one bit. Another person put it that we live in two different worlds.
Although there is still some suspicion, future cooperation appears to be coming.
The 'R' Factor - Ensuring operator workstation reliability
Operator workstations often get a bad rap. OEMs are well aware that the utility of their equipment or machinery depends in part on a user interface that may be no more than an afterthought in overall system design. Some go so far as to view workstations as disposable; assuming advances in technology will drive obsolescence more quickly than failure rates.
End users, especially those in industries where extremely harsh operating environments and mission critical requirements demand absolute reliability know otherwise, but often suffer from misplaced priorities. Engineers forced to specify workstations are regularly frustrated by the conundrum of tight budgets in opposition to special requirements. And in those larger OEM enterprises where in-house capabilities make workstation development possible, 'make or buy' decisions can subordinate pride to price/performance.
Where is the middle ground that will ensure workstation reliability at sustainable cost? Engineering conventions that support reliable operator workstation design are straightforward, if difficult to achieve. Among them:
Environmental Shielding - The best way to protect electronics from a hostile environment is to isolate them from that environment. While a sealed design is the cornerstone of operator workstation reliability, other factors may be just as important in ensuring reliable operation. EMI/RFI, wide swings in ambient temperature, shock & vibration, and liquids & particulate must be considered when designing the electronic system's mechanical package.
Temperature Rise - Designers often address environmental shielding issues by placing a standard industrial PC in a fully sealed enclosure. However, this fails to consider the inevitable temperature rise caused by totally sealing an electronic system designed to run with the use of outside air for venting. However, a combination of low-power components, cool-running displays, and careful management of internal sources of heat build-up combine to make a fully sealed design practical.
Occasionally, circumstances combine to create extreme operating environments that require operator workstations be designed to withstand 'battlefield' conditions. A prototypical example lies in the offshore oil and gas exploration industry, where open-sea platform conditions offer some of the most extreme operating environments on earth, including hazard factors. With opportunity costs ranging into the millions daily and sophisticated drilling operations based on workstation control, reliability is hard science, not conjecture.
In an application with similar, although characteristically less challenging requirements, maritime propulsion systems vendors have specified workstations for engine monitoring and control capable of operation in rollover conditions. Effectively this means that as an element of safety and reliability the workstation must be capable of sustained operation during and after total salt-water submersion.
As a matter of standard procedure, the US Navy requires many classes of onboard electronic equipment to undergo 'barge testing,' which subjects equipment, including operator workstations, to shock levels up to 50Gs when a depth charge is detonated near the device while in operation. EMI shielding must be sufficient to ensure system reliability in the event of nuclear war.
While this review has deliberately avoided any discussion of system internals, hardened workstation design must never be subordinated to IT requirements. Enclosure, ventilation and replacement based on early obsolescence may appear to be rational strategies. But when The 'R' Factor is adequately considered, a totally sealed, highly durable solution is often the most economical solution.
Ed Conroy, Marketing Manager,
Azonix Corporation, Billerica, Mass.
Thanks to a tip from George Bournazian of BtB Marketing, I found AvantGo . For those of you using PDAs (personal digital assistant for those avoiding TLAs), this is a superb service. It works with Palm users like me, or the various PocketPCs based on Microsoft Windows CE. When you synchronize your PDA with the desktop, just connect to the internet also and you will receive your choice of various news, weather, sports, and health web pages formatted for your device. I receive news from USA Today, Wall Street Journal, The Weather Channel, FitForAll (fitness news), plus others every morning when I sync with the network drive.
Other good tools to check out are 'personal portals.' Octopus and OnePage provide ways for you to build personal portals combining your favorite pages like news, Control Engineering, and others in one convenient location.
I have long had mixed feelings about thin client computing. At the risk of revealing my age, I first learned computers in the mid-'70's while implementing MRP for a manufacturing company. We had a small IBM mini-computer and suffered through all the usual problems waiting for MIS (the IT department of those days) to get to our work. I was part of the PC revolution that gave computing power to the masses. Some of the revolutionaries these days are working to bring back the old terminals and centralized computing-but in a new form.
This architecture does make sense for manufacturing. You can load your HMI software on one big PC and link a series of 'thin clients' wherever you need a view or access. Updated releases need only be loaded once. Revisions and changes can be controlled. Hardware is less expensive. These are all positive. Also, today's thin clients are much more powerful than what we had 20 years ago. A user can access not only the HMI or control code, with proper access she can also make necessary changes. Depending upon set up, she could also send e-mails and update an Excel spreadsheet. Although controlled in a central location, users maintain local access to necessary tools.
Wonderware has accessed this in two ways. Microsoft Windows 2000 offers an enhanced Terminal Services enabling thin client computing. See July and September 2000 articles in Control Engineering. Expect to see other software companies add this to their portfolios.
A Wonderware integrator has developed a thin client platform used by Wonderware along with a growing number of other companies. ACP showed an enhanced version of ThinManager at ISA last August.
Of course, another type of 'thin client' has been out for about a year-browsers. Most HMI software companies have 'Web-enabled' the software so that views, and even some interaction, are possible anywhere over the network (intra- or inter-) via Internet Explorer or Netscape Navigator. Just like in other area of control, your options keep growing.
Are you considering some kind of thin client architecture? What kind? Let me know at firstname.lastname@example.org . I'll share the results in a future edition.
In Control Engineering November and December:
CNC Technology integrates with machine control
Software integration across sites
Product Focus on Flowmeters
Look for annual Operator Interface Terminal reader survey and round up in December
Products to watch
Rockwell Automation 's Entek Enpac handheld data collector and signal analyzer provides maintenance personnel with a machinery condition monitoring tool. It is compatible with a variety of machines.
Made2Manage provides e-business applications to allow companies to better interact with their value change. The latest release adds integrated Bill of Materials and routings, a customer relationship management toolbar, VBA, and options for physical inventory tags.
Further in the realm of handheld computing tools, Psion Teklogix has the Teklogix 7520 Windows CE-based computer that supports IEEE 802.11b wireless systems with an IP67 rating. Exor is jumping on the 'Palm' bandwagon with the 'ePalm' series handheld HMI display with keypad. It provides eight lines of 20 characters each and weighs in at 4.7 lbs.
Camstar has released InSite version 2.0. This enterprise management application provides multi-plant manufacturers the ability to control underlying process modeling and data definitions for individual plants from a central location while allowing for localization and plant-specific configurations.
Formosa USA 's newest addition is a 15.1-in. active TFT LCD XGA display rated NEMA 4/12.
Azonix ProPanel line now runs on Intel processors up to 600 MHz with vibration resistance to 1G peak to peak in a 10-500 Hz operating frequency range and shock resistance boosted to 5Gs for 10 ms duration across three dimensions.
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