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。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年世界上套以微處理為基礎(chǔ)的分散式計(jì)算機(jī)控制系統(tǒng)問世，它以多臺(tái)微處理器共同分散控制，并通過數(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)
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。
現(xiàn)場(chǎng)總線在發(fā)展的初,各個(gè)公司都提出自己的現(xiàn)場(chǎng)總線協(xié)議。IEC組織于1999年12月31日投票,確定了8大總線作為國(guó)際現(xiàn)場(chǎng)總線標(biāo)準(zhǔn),其中包括CANBus、ProfitBus、InterBus-S、ModBus、FOUNDA-TIONFieldbus等等。而在此基礎(chǔ)上形成了新的現(xiàn)場(chǎng)總線控制系統(tǒng)（FieldbusControlSystemFCS）。它綜合了數(shù)字通信技術(shù)、計(jì)算機(jī)技術(shù)、自動(dòng)控制技術(shù)、網(wǎng)絡(luò)技術(shù)和智能儀表等多種技術(shù)手段,從根本上突破了傳統(tǒng)的“點(diǎn)對(duì)點(diǎn)”式的模擬信號(hào)或數(shù)字———模擬信號(hào)控制的局限性,構(gòu)成一種全分散、全數(shù)字化、智能、雙向、互連、多變量、多接點(diǎn)的通信與控制系統(tǒng)。相應(yīng)的控制網(wǎng)絡(luò)結(jié)構(gòu)也發(fā)生了較大的變化。FCS的典型結(jié)構(gòu)分為3層：設(shè)備層、控制層和信息層。
雖然現(xiàn)場(chǎng)總線技術(shù)發(fā)展非常迅速,但也存在許多問題,制約其應(yīng)用范圍的進(jìn)一步擴(kuò)大。
TB Woods Volkmann 72350G1 Adjustable-Speed AC Drive
TB WOODS WF2C4005-0B NSFP WF2C400503
TB WOODS WF2C4005-0D NSFP WF2C40050D
TB WOODS WF2C4075-0A NSFP WF2C40750A
TB WOODS WF2C4150-0D NSFP WF2C41500D
TB WOODS WFC-2020-OCHT USPP WFC2020OCHT
TB Woods WFC4010-0AHT High Torque E-Trac Drive 10hp 17.7kVA 460V WOW
TB WOODS WFC4010-0CHT 10HP 460VAC AC DRIVE XLNT
TB WOODS WFC4010-0CHT USPP WFC40100CHT
TB WOODS WFC4015-0CHT AC INVERTER DRIVE 15HP 28.4A XLNT
TB WOODS WFC4015-0CHT USPP WFC40150CHT
TB WOODS WFC4020-0CHT 380-460VAC 20HP
TB WOODS WFC4020-0CHT USPP WFC40200CHT
TB WOODS WFC4025-0C NSFP WFC40250C
TB WOODS WFC4030-0C USPP WFC40300C
TB WOODS WFC4040-0CHT USPP WFC40400CHT
TB WOODS WFC-4050-0CHT USPP WFC40500CHT
TB Woods WFC5010-0C AC Drive 10HP 575V WOW
TB WOODS X2C4010-0B USPP X2C40100B
TB WOODS X2C4015-0B NSFP X2C40150B
TB WOODS X4C4030-0C USPP X4C40300C
TB43225AF14 General Electric / GE Molded Case Reconditioned
TB63500 General Electric / GE Molded Case Reconditioned
TB63600 General Electric / GE Molded Case Reconditioned
TB83500 General Electric / GE Molded Case Reconditioned
TB83600 General Electric / GE Molded Case Reconditioned
TB83800 General Electric / GE Molded Case Reconditioned
TBEA GC-5KTL PV inverter
T-Berd 950 Communications Analyzer
TBFC WESTINGHOUSE THREE PHASE MOTORS AS-IS
TBFC WESTINGHOUSE THREE PHASE MOTORS REMANUFACTURED
TBG6539N TOSHIBA 3-PHASE FULL-WAVE SINE-WAVE PWM BRUSHLESS MOTOR CONTROL 5440pcs
TCI-002 USPP
TCI HARMONIC GUARD
TCI High Performance Output Filter KMG8A 480V 3P ( )
TCM1.1-04 INDRAMAT DRIVES REMANUFACTURED
T-COM 220A+ Dual DS-1 Line & Channel Monitor Test Set
T-Com Model 235-A Telecommunications T-1 Analyzer w/Leads, Manual, Case
TDA1.1-100-3-L00 INDRAMAT DRIVES AS-IS
TDA1.3-100-3-D INDRAMAT SERVO AMPLIFIER REMANUFACTURED
TDA1.3-100-3-D01 INDRAMAT SERVO AMPLIFIER REMANUFACTURED
T-Damper, 2 Blade, Beck Actuator, 14 inch
T-Damper, 2 Blade, electric actuator, 18 inch
T-Damper, Bettis Actuators, 12 inch
TDC module 6DD1600-0AK0 good in condition for industry use
TDI DLR-400-15-2500
TDI DLVP50-300-3000A
TDI DYNALOAD RBL488 50-1000-4000 Electronic Load 50V 1000AMP 4000W
TDI Dynaload RBL488 50-150-800 800W Digital Power Load Test Tester Pulse Shaping
TDI Dynaload Transistor Devices RBL 488-50-1000-4000 Manufacturer Refurbished
TDI DYNALOAD WCL232 50-1200-12000 Master WCL ELECTRONIC LOAD
TDI DYNALOAD WCL232 50-1200-12000 Master WCL WCL232-50-1.2K-12K
TDI Dynaload WCL488-100-1000-12000 Electronic Load
TDI Dynaload WCL488-50-1200-12000 Electronic Load
TDI MCL488
TDI Power Dynaload WCL-Water-Cooled WCS 400-1000-12000 Electronic DC Load Bank
TDI RBL100-600-4000
TDI RBL400-300-2000
TDI RBL488-100-300-2000
TDI RBL488-400-600-4000
TDI RBL488-50-1000-4000 Dynaload, 10, 20 or 50 Volts, 100, 500, 1000 Amps, 4KW
TDI RBL488-600-40-800 Load Cell 600V 40A 800W
TDI SPS5610-1
TDI Transistor Device Electronic Load RBL488 50V,400A,2000Watts
TDI TRANSISTOR DEVICES RBL1000-100-3000 Electronic Load 0-1000V 0-100A 3000W
TDI WCL488-100-1000-12000
TDI WCS-100-1000-12000
TDK MSE181H DC POWER SUPPLY
TDK-Lambda DC Power Supply GEN 200-75-LAN-3P208-1683
TDK-Lambda DC Power Supply GEN 125-80-LAN-3P400 Semitool 73147-77
TDK-Lambda GEN 20-165 / Agilent N8734A
TDK-Lambda GEN 20-165
