為了克服DCS系統(tǒng)的技術(shù)瓶頸,進(jìn)一步滿足現(xiàn)場(chǎng)的需要,現(xiàn)場(chǎng)總線技術(shù)應(yīng)運(yùn)而生,它實(shí)際上是連接現(xiàn)場(chǎng)智能設(shè)備和自動(dòng)化控制設(shè)備的雙向串行、數(shù)字式、多節(jié)點(diǎn)通信網(wǎng)絡(luò),也被稱為現(xiàn)場(chǎng)底層設(shè)備控制網(wǎng)絡(luò)（INFRANET）。和Internet、Intranet等類型的信息網(wǎng)絡(luò)不同,控制網(wǎng)絡(luò)直接面向生產(chǎn)過(guò)程,因此要求很高的實(shí)時(shí)性、可靠性、資料完整性和可用性。為滿足這些特性,現(xiàn)場(chǎng)總線對(duì)標(biāo)準(zhǔn)的網(wǎng)絡(luò)協(xié)議作了簡(jiǎn)化,省略了一些中間層,只包括ISO/OSI7層模型中的3層：物理層、數(shù)據(jù)鏈路層和應(yīng)用層。
計(jì)算機(jī)及 網(wǎng)絡(luò)技術(shù)與控制系統(tǒng)的發(fā)展有著緊密的聯(lián)系。最早在50年代中后期，計(jì)算機(jī)就已經(jīng)被應(yīng)用到控制系統(tǒng)中。60年代初，出現(xiàn)了由計(jì)算機(jī)完全替代模擬控制的控制系統(tǒng)，被稱為直接數(shù)字控制（DirectDigitalControl,DDC）。70年代中期，隨著 微處理器的出現(xiàn)， 計(jì)算機(jī)控制系統(tǒng)進(jìn)入一個(gè)新的快速發(fā)展的時(shí)期，1975年世界上第一套以微處理為基礎(chǔ)的分散式計(jì)算機(jī)控制系統(tǒng)問(wèn)世，它以多臺(tái)微處理器共同 分散控制，并通過(guò) 數(shù)據(jù)通信網(wǎng)絡(luò)實(shí)現(xiàn) 集中管理，被稱為 集散控制系統(tǒng)（DistributedControlSystem, DCS）。
進(jìn)入80年代以后，人們利用微處理器和一些外圍電路構(gòu)成了數(shù)字式儀表以取代模擬儀表，這種DDC的控制方式提高了系統(tǒng)的控制精度和控制的靈活性，而且在多回路的巡回采樣及控制中具有傳統(tǒng)模擬儀表無(wú)法比擬的性能價(jià)格比。
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Bently Nevada Probe Proximity Vibration Sensor 8mm 12508-02-12-10?-02 (5499)
BENTLY NEVADA 81544-01 USPP 8154401
BENTLY NEVADA 330101-00-08-0?5-02-01 NSPP 33010100080502?01
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BENTLY NEVADA 19004-02-12-18?-02 USPP 1900402121802
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NEW Bently Nevada 7200 Vibration Monitor Meter Rack Ready Card Assembly 72101-04
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BENTLY NEVADA 78596-01D NSPP 7859601D
Bently Nevada Vibration Probe 8mm 21504-00-28-10?-02 (7641)
Rolls Royce Bently T Series11AC Lucas Alternator 23578
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NEW BENTLY NEVADA 83729-01T SIGNAL INPUT/QUAD RELAY CARD OPTION PLC MODULE 47516
Bently Nevada Proximitor Probe 330909-05-29-1?0-0200 NEW
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BENTLY NEVADA 330130-080-00-?00 USPP 3301300800000
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BENTLY NEVADA 82368-01 NSPP 8236801
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BENTLY NEVADA 90125 9000 SERIES VIBRATION MONITOR BOARD CARD MODULE 46314
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BENTLY NEVADA 78432-02 USPP 7843202
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BENTLY NEVADA 18745-04 5MM PROXIMITOR 7200 SERIES PROXIMITY SENSOR SWITCH 59103
BENTLY NEVADA 3300 XL 8MM PROBE 330101-00-60-1?0-02-05
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BENTLY NEVADA PROXIMITOR SENSOR 330100-90-00 *NEW*
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BENTLY NEVADA 30004-02-12-18?-02 NSPP 3000402121802
NEW BENTLY NEVADA 330900 PROXIMITOR SENSOR 330900-50-05
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BENTLY NEVADA 18745-01 7200 PROXIMITOR PROXIMITY SENSOR 5MM -18 TO -24V DC 55419
BENTLY NEVADA 14386-03 7200 SERIES PROXIMITOR I/O MODULE 24V DC 46471
BENTLY NEVADA 24145-02 ACCELROMETER MODULE INTERFACE BNC 24V DC 46458
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