Moxa white paper---Embedded Computing for Industrial Embedded Computing for Industrial Applications


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Moxa white paper---Embedded Computing for Industrial Embedded Computing for Industrial Applications

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Moxa white paper---Embedded Computing for Industrial Embedded Computing for Industrial Applications

  1. 1. Moxa White Paper Embedded Computing for IndustrialApplicationsReleased on May 1, 2008Copyright © 2008 Moxa Inc. All rights reserved.Moxa manufactures one of the world’s leading brands of device networking solutions. Products include industrialembedded computers, industrial Ethernet switches, serial device servers, multiport serial boards, embeddeddevice servers, and remote I/O products. Our products are key components of many networking applications,including industrial automation, manufacturing, POS, and medical treatment facilities.How to contact MoxaTel: 1-714-528-6777Fax: 1-714-528-6778Web: www.moxa.comEmail: info@moxa.comThis document was produced by the Moxa Technical WritingCenter (TWC). Please send your comments or suggestionsabout this or other Moxa documents to Hsu, Moxa Project Managerandrew.hsu@moxa.comIt’s safe to say that everyone knows what a computer is.However, that said, many people remain blissfully unaware ofthe distinction between a general-purpose computer, and aso-called “embedded computer.” General-purpose computers,such as the typical office PC, are used to run a variety ofprograms and applications. For example, most people have atone time or another used word processing software,spreadsheet programs, email utilities, or any of the thousandsof computer games available on the market. In contrast,embedded computers are designed to handle a specificapplication, such as monitoring a security door, reporting thestatus of sensors for a control system, or managing trafficlights at a busy intersection.There are two main advantages to using embedded computers.The first is a big reduction in cost. The second is that they areeasy to deploy. In fact, both advantages are related to the sizeof the embedded computer. Since embedded computers tendto be much smaller than general-purpose computers, and donot require purchasing a monitor, keyboard, and mouse, thecost is quite a bit less than for a general-purpose computersystem. The reduced size also makes it easier to deployembedded computers at a large number of remote locations.The location of your application can have a big effect on thetype of equipment you purchase, and this is also true ofembedded computers. A simple example is an entry gateapplication. If the entrance is a door located inside an air
  2. 2. Moxa White Paper Embedded Computing for IndustrialApplicationsCopyright © 2008 Moxa Inc. Page 2 of 6conditioned building, then the embedded computer only needsto function reliably in a narrow temperature band and at arelatively low humidity. On the other hand, if the entrance islocated outdoors, you may need to use an embedded computerguaranteed to operate reliably in extremely cold temperatures(e.g., as low as -35°C), and in extremely hot temperatures(e.g., as high as +70°C).For embedded applications subject to harsh environmentalconditions, you should look for embedded computers that meetall of the following specifications:Ready access: A robust design and remote managementcapability are a must to reduce maintenance costs andensure that the embedded computer operates reliably.Reliable communication: For applications that require adistributed system architecture, be sure to use embeddedcomputers that offer a choice of interfaces and supportsecure transmission protocols.Fit for harsh environments: Many industrial applicationscall for a DIN-rail form factor and wide operatingtemperature support. For buses and installation on machineswith moving parts, an anti-vibration guarantee must also beconsidered.Versatile expansion options: Embedded computers with arich variety of expansion slots, memory options, andcommunication ports give system integrators more optionswhen designing new systems and when reusing existingequipment for other applications.Efficient management: Being able to install embeddedcomputers quickly and easily is essential when dealing withlarge systems. In addition, a remote management capabilityincreases the reliability of your system, and makes it easy toconfigure and update firmware and software.The Move towards Greater VersatilityEven though embedded computers do not require a monitor,keyboard, and mouse, they still need some means of
  3. 3. Moxa White Paper Embedded Computing for IndustrialApplicationsCopyright © 2008 Moxa Inc. Page 3 of 6communicating with other devices in the system. At the bareminimum, the computers should have one or two serial portsfor connecting to external devices. However, for the embeddedcomputer to be a viable component of a modern controlsystem, it should also be able to connect to a number of otherinterface types:Serial Communication Interfaces (SCI): RS-232,RS-422, and RS-485 are the standard serial interfaces forindustrial applications.Universal Serial Bus (USB): Although theRS-232/422/485 interfaces are still the norm for industrialapplications, USB is starting to make inroads.Networks: Ethernet is now pervasive in the office and homeenvironments, and is being used more and more in industrialsettings. In addition, some industrial applications use theCAN (Control Area Network) protocol.Discrete IO: Large-scale control systems make liberal useof General Purpose Input/Output (GPIO) technology.Analog to Digital/Digital to Analog (ADC/DAC): Thecapability to convert analog signals to digital signals and viceversa is a requirement for many industrial applications.Wireless Communication Interface: Industrialapplications located in hard-to-wire settings can benefit byusing wireless connections to transmit data over a network.WWAN(Cellular Network)WLAN(Short RangeTransmission)GSM/GPRS/CDMA +3G/UMTS/HSDPAWLAN 802.11 a/b/g WLAN 802.11 b/g+
  4. 4. Moxa White Paper Embedded Computing for IndustrialApplicationsCopyright © 2008 Moxa Inc. Page 4 of 6Embedded Computers for Harsh EnvironmentsIn contrast to secure, temperature-regulated officeenvironments, harsh environment applications needequipment with a rugged design. Your embedded computersshould have a robust and compact metal housing, use few (ifany) cables, and use no moving parts such as hard discs andcooling fans. Hard disks, in particular, crash or fail relativelyoften, which makes using flash memory an attractivealternative. In addition, anti-vibration and anti-shock featurescan improve the stability of systems used on buses, trucks,trains, and other moving objects.Wide Temperature DesignA wide operating temperature design is a key factor forapplications that run in critical, outdoor environments, sincetemperatures could range from as low as -35°C to as high as+70°C. For this reason, you should choose embeddedcomputers made from high quality components thatgenerate less heat, and have a long MTBF. If you have doubtsabout a computer’s ability to work reliably in cold and hottemperatures, be sure to ask the manufacturer to providethe proper verification and certification documents.Isolation ProtectionElectronic equipment can benefit from using optical isolationtechnology to protect against ground voltage loops and otherelectrical disturbances. The isolator works by converting anelectrical signal into a light signal, which is transmitted across ashort gap in the electronics. When the light signal reaches theother side of the gap, it is converted back into an electricalsignal. The gap that’s created in the electronic circuit is oftenplaced between a transmitter and receiver.A common problem for many RS-485 applications is groundloop currents that flow through the ground line when groundvoltage levels differ between connected devices. To eliminatethis problem, some RS-485 products come with up to 2 KV of
  5. 5. Moxa White Paper Embedded Computing for IndustrialApplicationsCopyright © 2008 Moxa Inc. Page 5 of 6optical isolation protection.If the RS-485 network covers a fairly long distance, isolationprotection keeps the RS-485 devices’ interface componentsfrom getting fried. You should look for products that offer atleast 2 KV of optical isolation protection.Customer-friendly FeaturesFor time-to-market considerations, embedded computersshould be much more than just a hardware box that requiresextensive installations and configurations. Look for thefollowing important features when deciding what type ofembedded computer to purchase for your industrialapplications:Ready-to-run operating system: Most system integratorsand other embedded computer users now look for computerswith a pre-installed operating system, drivers, file systems,and common applications such as Open VPN or IPsec VPN.Protocol conversion: Embedded computers must oftenconnect to a variety of devices that don’t always use thesame communication protocol. For this reason, you shouldlook for suppliers that provide convenient protocolconversion software to ease the task of passing data backIsolator isinstalledhereHigher Voltage Lower VoltageGround LoopComputerRoomSerialDevice15 m to 1 km serial connectionGround is charged
  6. 6. Moxa White Paper Embedded Computing for IndustrialApplicationsCopyright © 2008 Moxa Inc. Page 6 of 6and forth between different devices.Remote access: Mangers of many existing systems are stillfaced with the nightmare of needing to send engineers onsiteto manage their embedded computers. A simple way to turnthis nightmare into a memorable dream is to use embeddedcomputers that are accessible remotely over an Ethernet orcellular network. In addition, efficient online devicemanagement tools can save engineers many hours offrustration.SummaryIn this paper, we explained the basic difference between ageneral-purpose computer and embedded computer, andhighlighted the features that embedded computers shouldhave when used for industrial applications. The most importantfeatures are:• Wide temperature design• Isolation protection• Customer-friendly features• Ready-to-run operating system• Protocol conversion softwareNOTE: Moxa provides a rich selection of embedded computers for industrial applications.For details, check our website at, or contact the author, Andrew Hsu, document is provided for information purposes only, and the contents hereof are subject to change withoutnotice. This document is not warranted to be error-free, nor subject to any other warranties or conditions,whether expressed orally or implied by law, including implied warranties and conditions of merchantability, orfitness for a particular purpose. We specifically disclaim any liability with respect to this document and nocontractual obligations are formed either directly or indirectly by this document. This document may not bereproduced or transmitted in any form for any purpose, without our prior written permission.