So, of course, these desktops and laptops were armored in enclosures that separated them from the heat, cold, shock, vibration, moisture, dirt, corrosives, electrical noise, and other threats always so common on the plant floor. These protections allowed users to gain PCs’ data-processing capabilities, while sheltering their information, software, and the hardware that conveyed them.
Much has changed since PCs arrived on the plant floor, however, and even more is changing now. The very nature and definition of PCs has evolved, so that they’re often unrecognizable from the PCs of old. Sure, there are still numerous traditionally protected IPCs, but the line separating them from other control and automation devices is completely blurred, if not entirely gone. This evolution makes it even more important now for users to take care in selecting and implementing the most appropriate solution for their application.
“We’ve used and implemented industrial PCs for 20 years, and my perception of today’s controls market is that a large percentage of industrial applications are using low-cost, white-box PCs, and that many are working just fine and achieving long lifespans,” says Rick Caldwell, president of SCADAware Inc., a system integrator in Bloomington, Ill. “In general manufacturing, these are usually Dells or equivalent PCs that are partially or poorly enclosed, and often not in an enclosure at all.
“Of course, there are times when PCs can’t serve alone, and where they still need to be in a professional enclosure. However, much of the former IPC market has dried up, and isn’t what it was. Users are much more willing to use regular PCs in industrial setting because IPC systems that used to cost $12,000 in the mid-1990s are now selling for $400. So, the costs are such that people aren’t afraid to use PCs because it’s still cheap to buy a second one.”
In fact, some industrial applications, such as steel production, may replace as many as a third of their PCs per year, according to Phil Aponte, Siemens’ HMI product marketing manager. “This is costly, but it’s better than risking a critical, onsite failure,” he says. “Some users have had to shutdown their facilities because they used off-the-shelf computers when they shouldn’t have done it. This is where IPCS can help.”
Bjoern Falke, Phoenix Contact’s automation marketing manager, adds that IPCs also historically offer legacy connection options, such as ISA bus and parallel port, industrial-grade mounting options, and touchscreens to eliminate the need for a keyboard and easily change machine parameters. “The entire IPC design needs to be able to withstand the shock and vibration, as well as the EMI noise levels, found in an industrial setting,” he says. “Besides high immunity to electrical noise, users mostly need a dust-proof, water-tight front-bezel, probably IP65, or an entirely dust-proof, such as IP50 or higher. For applications exposed to a high amount of vibration or shock, a traditional rotating hard drive now can be replaced by a non-rotating media.”
Morphing Forms
Despite declining prices, or perhaps partially because of them, many PCs’ forms, functions, power, data storage, networking capabilities, and other once-essential characteristics are often totally different now. Naturally, all of this evolution is finding its way into industrial PCs (IPCs), whose developers are adding many innovations of their own.
“Industrial PCs now come in many more useful form factors to meet the needs of each application, whether it’s displaying data, collecting it, or interfacing with users,” says Ann Ke, Wonderware’s IPC product manager. “However, what they all still have in common is a need to withstand industrial environments, so the production lines and processes they’re linked to don’t break down. Even whether you need a hard drive really depends on the application. Certain lower-end operations can just use a flash card, while doing HMI on the plant floor, collecting data, or running a SQL database or historian really needs a hard drive. Solid-state drives are available, which Wonderware has as well, but they still cost more, though they might be worthwhile for some applications.”
Typical environmental stresses for IPCs include temperature, which usually is countered with heaters below 0 ºC and with ventilation above 50 ºC. Next, an IPC’s internal components are rated to withstand certain levels of shock and vibration, and then more shock-absorbing protection is added to each system. For example, the silicon padding that Ke reports is added externally to the hard drives of Wonderware’s Industrial Tablet and Touch Panel computers reportedly protects them from on-edge drops. Similar barrier-type protections are added to prevent intrusion by water, chemicals, and other harsh substances, and testing determines their two-digit ingress protection (IP) ratings (see sidebar).
“In my mind, an IPC is a 12-15 in. panel-mounted computer with an enclosed front and back end that can sit anywhere,” says Caldwell. “Now, an IPC can be everything from a 4 x 4-in., diskless, DIN rail-mounted computing device to an entire Dell PC tower.”
These shifting definitions of IPCs can make it harder for users to find the right computer for their application, but it also gives them far more choices and potentially useful solutions and savings then in the past. “Industrial PCs are an equal or better replacement for PLC in a lot of industrial applications,” adds Falke. “Users sometimes prefer the security of PLCs due to their proprietary software, which can’t easily be corrupted by viruses or other PC software. Phoenix Contact addresses those applications with its new Steeplechase VLC-programmed, embedded controllers, such as the S-MAX VLC, that offer the security of a PLC with the speed and connection options of a PC.”
Nipun Mathur, National Instruments’ (NI) DAQ product manager, adds that, “Ten years ago, industrial PCs just displayed control and I/O tasks on an HMI, but then they began getting ruggedized and enclosed in 19-in. rack for use on the plant-floor, which moved them closer to PLCs. Meanwhile, PLCs became more open, and added faster processors, advanced analytics, and control algorithms, which pushed them toward the process automation controllers (PACs) and IPCs,” says “Now, the hardened laptop or blackbox on a 19-in. rack concept has been broken out into all new areas. So, while the PLC automated tasks for more efficiency, more advanced control and plant monitoring requires a platform that runs both high-speed control and real-time analytics, and that’s what a PC can do well.”
For example, ABCO Automation reports it recently used NI’s PC-based PACs to develop a 14-station assembly and verification conveyor line and a 10-station final testing line for an automotive sensor manufacturer. To help the line produce its mandated one part every six seconds, NI’s LabVIEW Data Socket was integrated with Rockwell Automation’s Allen-Bradley RSLinx OPC server, which allowed NI’s PAC hardware to work better with traditional PLCs, and provide seamless control and data monitoring. NI adds its new ability to speak to A-B’s hardware saved it valuable programming and integration time on ABCO’s job.
In addition to evolving in the direction of PLCs and carrying our their functions, IPCs also can serve independently as headless network servers, collect data from machines, and pass it up to enterprise levels, according to Aponte. “We have one user that mounted our Microbox T computer in a confined space for automatic, material-handling control because he needed an IPC to control drives and motors, but still be close enough to his application’s actuators. “This was a job that PLCs did in the past because they were the real-time devices and PC were not, but dual-core Intel processors are allowing much more PLC-like control by industrial PCs.”
Don’t Move
Probably the most significant recent change in industrial PC technology is the increasing use of Flash memory and cards. Because these components have no moving parts, they’re much less vulnerable to many of the environmental stresses that can plague fast-spinning hard drives or their related cooling fans. Logically, less vulnerability inside a device means less need for protection outside a device. “The users’ preference is naturally to get rid of hard drives, fans, and any other moving media,” says Aponte.
Beckhoff Automation's CX1000 embedded PC helps manage bus couplers monitoring Shanghai's growing wastewater treatment system.
For example, the Shanghai Water Environment Investment Co. recently added Beckhoff Automation’s CX1000 embedded PC to help manage Beckhoff’s bus couplers, which already were monitoring its growing wastewater treatment system in the city’s Xu Jia Hui district (see Figure 1). “The use of fanless, non-rotating PC components, and its embedded operating system are the basis for CX1000’s stability and reliability,” says Huang Cheng, Shanghai Water’s manager. “In our experience, this PC-based, software PLC not only offers the functionality of a conventional PLC, but can also deal with far higher data quantities than a conventional solution.”
Mathur adds that NI’s staffers recently threw one its Compact RIO PACs off the 9th floor of its headquarters, while the device was in the process of acquiring data, and that it still functioned properly. Compact RIO also uses Flash data storage and has no rotating parts.
“Fanless PCs allow for more protection and higher NEMA/IP ratings because no air needs to be moved out of the PC’s enclosure. This means the PC’s housing can be completely sealed,” says Falke. “This type of PC can be mounted directly in a machine, such as on a pendant arm, and eliminates the need for an industrial enclosure to house the PC. Phoenix Contact’s Vehicle Mount Terminals (VMT) are examples of these fanless, direct machine-mount PCs.”
At a time when there are so many IPC forms factors, it’s even more important now that so many are running Microsoft Windows software, according to Graham Harris, Beckhoff’s president. “Windows gives good data processing, file sharing, communications with .Net environments, and with CE for real-time controls, which doesn’t need a real-time kernel like a PLC,” says Harris. “This is another case of software being applied via the necessary hardware. As the saying goes—‘Software defines, and hardware implements.’ ”
At a Distance
Besides decreasing the need for protection by eliminating moving parts, developers also are breaking up traditional IPCs into separate functions. These can be prioritized, allowing some more vulnerable, less easily protected functions to be moved away from hazardous areas, which can greatly reduce costs. This also means that more resources can be devoted to protecting functions that must remain in those areas.
For instance, Wonderware recently introduced its Box PC, which has a processor and hard drive, but no display. It’s designed for machine builders, who want to mount their displays away from their PC units. This allows the PC to be located in a machine panel with PLCs and I/Os, but allows the operator to be situated elsewhere.
Similarly, Ke adds that Wonderware also recently launched its Thin Client computer, which allows users to view and access its InTouch software or Client Server HMI at the terminal/node, while actually working off a server that can be located remotely. “Everything runs on the server, and the thin client just shows up as a session on it,” explains Ke.
Bettering Boards
Aponte adds that industrial PCs are adversely affected by the greater speed of development in the mainstream PC realm. “The span of motherboards and other PC product lifecycles are very important in how industrial PC are able to develop,” says Aponte. “Typical PC models usually change every three to six months, but industrial and automation application usually demand PLCs with a minimum 10-year lifecycle. The computer industry can’t provide this, so IPCs usually have three to five-year lifecycles.
“For instance, we have automotive production PCs running Microsoft NT, which will soon be unsupported,” says Aponte. “However, the user can’t upgrade to XP, so Siemens took over ownership of this solution, and will provide long-term support of NT on this IPC.”
Aponte adds that he’s seeing IPC technology surfacing in Siemens’ Microbox T embedded XP platform, which creates images of common industrial ports, and runs in a fanless, diskless, DIN rail-mountable in hardware format. Microbox T reportedly provides motion functions that were previously only available in a PLC, while the newly introduced Microbox RTX also offers soft PLC control and visualization.
“Standard IPC and PLC technologies now allow users to buy software from many places, and so we can provide pre-installed, fanless, diskless bundles that eliminate the most failure-prone hard drive and heating problems of traditional IPCs, as well as allowing smaller enclosures” adds Aponte. “We basically put the PC’s functions onto an embedded XP image, which provides electronic write files, and also prevents the addition of unauthorized programs. In fact, even if this software was lost, you could just plug in a new compact Flash card.
While diskless and fanless IPCs now get most of the attention, systems receiving a lot of varied, non-repetitive analog data may still need to use one or more hard drives, according to Derrick Lovado, Kontron’s embedded systems product manager. Besides rugged chassis, some box-type or rackmount IPCs now have hot-swappable fans, redundant power, and multiple hard drives arranged in a redundant, array, inexpensive disk (RAID) system, which is governed by a RAID controller.
“The typical Level 5 RAID system mostly uses three or four disks, and stripes data across all of them,” says Lovado. “This is extremely fast, and gives each drive the data from the other. This means you can recreate any data lost by one drive because the others know what it should posess. These systems are very inexpensive now because the drives cost much less.” He adds that Kontron is releasing in August its new Industrial Silent Server, a rack-mount IPC with an ATX motherboard or passive backplane.
In addition, Stealth Computer Corp. reports that simply implementing the appropriate computer board can deliver essential advantages. For instance, conventional PCs and IPCs locate most of their electronics on one large motherboard or main board, and replacing it requires completely disassembling and removing all cards and cables from the system. Downtimes range from 30 minutes to several hours, and frequent model and device driver changes and scarce replacement parts can increase delays even more. ogy changes literally on a monthly basis, it is sometimes impossible to find an exact replacement. Another concern is the availability of expansion slots because many motherboards don’t have as many ISA/PCI slots as they did in the past.
Stealth adds that single-board computers (SBCs) contain all the functions of conventional motherboards, but are designed as single plug-in caerds, which look similar to a standard ISA/ PCI cards. These SBCs plug directly into the IPCs passive backplane, which simply combines ISA/PCI expansion slots into which the SBC and other cards are inserted. Available backplane configurations typically have two to 20 slots or more.
In addition, Stealth adds SBCs often have built-in watchdog timers that can cause a reset if they determine that the system has either hung up or is no longer executing the correct code sequence of code. In electrically noisy environments, for example, a power glitch may corrupt the program counter, stack pointer, or data in RAM. This means the PC’s software could crash, even if the code is bug free. This is precisely the sort of transient failure that watchdogs will catch.
Environmental Protection Definitions
NEMA and CSA Enclosure Types
In its “Basics of Explosion Protection” whitepaper, R. Stahl covers many of the environmental issues that must be considered by users evaluating protection for workstations, enclosures, and industrial PCs. These types originate from the National Electrical Manufacturers Association (NEMA) and the Canadian Standards Association.
- Type 1 are for indoor use, and protect against limited amounts of falling dirt. This type is not specifically identified in CSA’s standard.
- Type 2 are for indoor use, and protect against limited amounts of falling water and dirt.
- Type 3 are for outdoor use, and protect against rain, sleet, windblown dust, and damage from external ice formation. Type 3R must also have a drain hole. Type 3S must also have external mechanisms that can operate when laden with ice.
- Type 4 are for indoor or outdoor use, and protect against windblown dust and rain, splashing and hose-directed water, and damage from external ice formation. Type 4X must also protect against corrosion.
- Type 5 are for indoor use, and protect against settling airborne dust, falling dirt, and dripping non-corrosive liquids.
- Type 6 are for indoor or outdoor use, and protection against hose-directed water, entry of water during occasional temporary submersion at a limited depth, and damage from external ice formation. Type 6P must also protect against entry of water during prolonged submersion at a limited depth.
- Type 12 are for indoor use, and protect against circulating dust, falling dirt, and dripping non-corrosive liquids. Type 12K must offer the same protection for enclosures with knockouts.
- Type 13 enclosures are for indoor use, and protect against dust, spraying water, oil, and non-corrosive coolants.
Ingress Protection Codes
The International Electrotechnical Commission (IEC) uses the term “ingress protection” (IP) to identify the environmental protection of a device. This is defined in IEC’s 60529 standard. This chart in Stahl’s whitepaper shows how the two-digit IP classification codes are used. Basically, the IP system designates the degree of protection provided by a device against ingress of dust and water.
First IP Digit is the degree of protection against solid objects
- 0 non-protected
- 1 protected against a solid object greater than 50 mm, such as a hand
- 2 protected against a solid object greater than 12mm, such as a finger
- 3 protected against a solid object greater than 2.5mm, such as wire or a tool
- 4 protected against a solid object greater than 1.0 mm, such as wire or thin strip
- 5 dust-protected, and prevents ingress of dust sufficient to cause harm
- 6 dust tight; no dust ingress
Second IP Digit is the degree of protection against water
- 0 non-protected
- 1 protected against water dripping vertically, such as condensation
- 2 protected against dripping water when tilted up to 15°
- 3 protected against water spraying at an angle up to 60°
- 4 protected against water splashing from any direction
- 5 protected against jets of water from any direction
- 6 protection against heavy seas or powerful jets of water
- 7 protected against harmful ingress of water when immersed between 150mm and 1 meter
- 8 protected against submersion, and suitable for continuous immersion in water
