開關,路由器,集線器,網關,連接器和其他以太網硬件已被通過工業化的手段變得易于生產制造。
工業以太網硬件可以不用在圍欄中就能承受大負荷,允許較短的電纜在簡易的分布式(勝于集中式設計)設計中運行,這要比在商業水準的以太網開關,路由器,集線器,網關和接線器上運行更可靠。工業額定電壓(如NEMA 4x 或IP67更高)應用在以太網硬件中,意味著設備可以處理極致溫度(如-40到85 °C)甚至是處理液體和塵土,以及性能維修而達到更長的使用年限。
如果商業以太網設備都是可靠且性能良好的,則足以利用其可靠性。此外,較高的工業設計成本將會平均減少,阻止過程中斷以及數據損失,綜上全部取決于應用。例如,西科系統有限公司,著名的互聯網設備供應商,是行業企業中完成嚴峻工業環境挑戰的公司之一。西科與霍尼韋爾、羅克韋爾自動化達成了穩步協議,共同在應用過程和離散制造操作過程中最大程度地理解客戶需求。
工業包裝
奧普圖高級技術顧問Tom Edwards承認:包裝也能夠創造奇跡。此舉使得以太網硬件更適合于工業環境。許多不需要支架的設備尤其適合工業安裝,如果在這些設置類型中其可以被保護不再經受來自正常的撞擊和刮傷。許多工業設備的額外費用就是包裝費,把硬件放入合適的19-架里,這樣雖然產生費用但是可以避免硬件受損。
Tyco Electronics產品經理Greg Paukert說“為了使以太網設備工業化,Tyco Electronics公司使用的都是緊湊的耐沖擊塑料和橡膠原料,密封效果非常好,可阻止來自多種化學物品的侵蝕,包括水,產品使用的性能周期可達10年到20年。
“當人們在考慮工業額定電壓時,他們考慮更多的是硬件能否在非常惡劣的環境下操作,”AutomationDirect 通信產品部經理C hris Harris說,各種各樣的標準將應用于以太網工業環境中。
Harris說:“工業以太網硬件可在極端的溫度條件下進行操作,符合電涌(IEEE-472),極限振動(IEC 68-2-6)和在危險區域[UL 1604, CSA C22.2/213 (Class 1, Div. 2)]。”
Moxa技術公司產品營銷經理Eddie Lee說,設計差異意味著工業以太網開關的說明書中描述的通常是現行等級設備額定功率的2倍到3倍。擁有Class 1, Div. 2的額定功率的工業以太網可在存在可燃氣體或化學粒子存在的危險區域中操作,如在油氣中,半導體中,紙漿和其它市場。
施耐德在北美的自動化產品經理Richard Hutton說:“開關的頻率是多大通常很重要,如果一個開關或是電纜被頻繁的接通,那就要求更多粗糙的連接點或是設備。
信號干擾
Beckhoff自動化I/O系統產品經理Skip Hansen解釋說:“變頻驅動器通常與感應加熱器的噪音可能要伴隨著焊接工。使用的開關應具備安裝在控制盒或是單獨固定的能力。單獨固定的情況下,開關要出具證明通過IP67級保護。”
Phoenix Contact自動化美國業務部產品經理Larry Komarek說:“其它產生工業電氣噪音的設備還包括:螺線管,發動機和過程控制器。工業以太網設備是按照IEC1000-4系列說明書設計的,比商業設備所產生的噪音要低2倍到3倍,商用設備則是按照EN 55024 和50082-1說明書設計的。(待續)
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Who Puts the ‘Industrial’ in Ethernet?
Switches, routers, hubs, gateways, connectors, and other Ethernet hardware have been industrially hardened to take what manufacturing can dish out.
Industrial Ethernet hardware can take plant-floor punishment without pampering in enclosures, allowing shorter cable runs with simpler distributed (rather than centralized) designs, and higher reliability than commercial-level Ethernet switches, routers, hubs, gateways, and connectors. Industrial ratings (such as NEMA 4x or IP67 and beyond) applied to Ethernet hardware mean that equipment can handle temperature extremes (as much as -40 to 85 °C), and even liquid and dust, and maintain reliable performance for years instead of months.
If commercial Ethernet devices are reliably enclosed and cooled, that might be enough to preserve reliability. Beyond that, higher costs for industrial design will cut down on mean time between failures, possibly preventing a process interruption or data loss. It all depends on the application. Cisco Systems Inc., for instance, while well-known in various network application spaces, is among companies that realize that industrial environments pose rugged challenges. Cisco forged agreements with Honeywell and Rockwell Automation, who have greater understanding of customer needs in process and discrete manufacturing operations.
Industrial wrapping
Enclosures can work wonders, admits Tom Edwards, senior technical advisor, Opto 22. Edwards contends that installation is mainly “what makes Ethernet hardware suitable for industrial environments…. Most of the off-the-shelf equipment is perfectly suitable for industrial installation if it can be protected from the normal bumps and scrapes ... in these types of settings. Most of the extra cost of ‘industrial’ equipment is the packaging added to keep it from being damaged and to make it fit in a 19-in. rack.”
To make an Ethernet device industrial, says Greg Paukert, product manager, Tyco Electronics, using impact resistant plastics and rubber materials “seals against many chemicals including water to give the product a 10- to 20-year performance life.” Connectors that use a positive locking coupling system ensure the interconnection is “fully-engaged and properly mated,” Paukert adds.
When people think of industrial grade, they think of hardware that can operate under the harshest conditions, says Chris Harris, communications product manager, AutomationDirect. Various standards apply to making Ethernet industrial.
“Industrial hardware is expected to operate properly even when subjected to extreme temperatures, power surges (IEEE-472), extreme vibration (IEC 68-2-6), and when in hazardous locations UL 1604, CSA C22.2/213 (Class 1, Div. 2),” Harris says.
Signal interference
Design differences, says Eddie Lee, national product sales manager, Moxa Technologies Inc., mean that “specifications of industrial Ethernet switches usually are two to three times stronger than the ratings found in comparable office grade equipment.” The Class 1, Div. 2 rating for industrial Ethernet switches allows operation in hazardous locations where combustible gases or particles may be present, Lee says, such as in oil and gas, semiconductor, pulp and paper, and other markets.
How often a switch is exposed also makes a difference, says, Richard Hutton, automation product manager, Schneider Electric North America. “If a switch or cable is being accessed frequently, a more rugged connection point or device is required.”
Skip Hansen, I/O systems product manager, Beckhoff Automation, explains that a “noisy environment may be one with welders, variable frequency drives (VFDs) and induction heaters. The switches used should have the ability to be mounted in a control cabinet or stand alone. In the case of stand-alone, switches certified to the IP67 protection class should be considered.”
Other contributors to industrial electrical noise include solenoids, motors, and motion controls, says Larry Komarek, Phoenix Contact automation product manager, Americas Business Unit. “Industrial Ethernet devices designed to the IEC 61000-4 series of specifications have two to three times higher electrical noise immunity than commercial devices, which are typically designed to the EN 55024 and 50082-1 specifications,” Komarek says. Paukert from Tyco says expects more use of “shielded, plated plastic receptacles for >20dB down shield effectiveness.”[/COLOR]
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