描述
?FCS的關(guān)鍵要點(diǎn)有三點(diǎn)
(1)FCS系統(tǒng)的核心是總線協(xié)議,即總線標(biāo)準(zhǔn)
前面的章節(jié)已經(jīng)敘述,一種類型的總線,只要其總線協(xié)議一經(jīng)確定,相關(guān)的關(guān)鍵技術(shù)與有關(guān)的設(shè)備也就被確定。就其總線協(xié)議的基本原理而言,各類總線都是一樣的,都以解決雙向串行數(shù)字化通訊傳輸為基本依據(jù)。但由于各種原因,各類總線的總線協(xié)議存在很大的差異。
為了使現(xiàn)場總線滿足可互操作性要求,使其成為真正的開放系統(tǒng),在IEC國際標(biāo)準(zhǔn),現(xiàn)場總線通訊協(xié)議模型的用戶層中,就明確規(guī)定用戶層具有裝置描述功能。為了實(shí)現(xiàn)互操作,每個(gè)現(xiàn)場總線裝置都用裝置描述DD來描述。DD能夠認(rèn)為是裝置的一個(gè)驅(qū)動器,它包括所有必要的參數(shù)描述和主站所需的操作步驟。由于DD包括描述裝置通信所需的所有信息,并且與主站無關(guān),所以可以使現(xiàn)場裝置實(shí)現(xiàn)真正的互操作性。
實(shí)際情況是否如上述一致,回答是否定的。目前通過的現(xiàn)場總線國際標(biāo)準(zhǔn)含8種類型,而原IEO國際標(biāo)準(zhǔn)只是8種類型之一,與其它7種類型總線的地位是平等的。其它7種總線,不論其市場占有率有多少,每個(gè)總線協(xié)議都有一套軟件、硬件的支撐。它們能夠形成系統(tǒng),形成產(chǎn)品,而原IEC現(xiàn)場總線國際標(biāo)準(zhǔn),是一個(gè)既無軟件支撐也無硬件支撐的空架子。所以,要實(shí)現(xiàn)這些總線的相互兼容和互操作,就目前狀態(tài)而言,幾乎是不可能的。
通過上述,我們是否可以得出這樣一種映象:開放的現(xiàn)場總線控制系統(tǒng)的互操作性,就一個(gè)特定類型的現(xiàn)場總線而言,只要遵循該類型現(xiàn)場總線的總線協(xié)議,對其產(chǎn)品是開放的,并具有互操作性。換句話說,不論什么廠家的產(chǎn)品,也不一家是該現(xiàn)場總線公司的產(chǎn)品,只要遵循該總線的總線協(xié)議,產(chǎn)品之間是開放的,并具有互操作性,就可以組成總線網(wǎng)絡(luò)。
產(chǎn)品承諾:
保?證?全新原裝進(jìn)口,
保?證?安全準(zhǔn)時(shí)發(fā)貨,
保?證售后服務(wù)質(zhì)量,
優(yōu)勢價(jià)格,大量現(xiàn)貨。
主營DCS系統(tǒng)配件
機(jī)器人系統(tǒng)配件
大型伺服系統(tǒng)配件
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DYNATEC 510-6-P12-24 GLUE MACHINE USED*
GIANT LOT OF FUSES,GOULD SHAWMUT ,FUSETRON,BUSS,?
GOULDS ITT 1X1 1/4-6 COMMERCIAL WATER PUMP 1/2 HP, NEW
RELIANCE ELECTRIC 3RA2004 SERVO DRIVE USED
RELIANCE ELECTRIC BRUSHLESS AC SERVO CONTROLLER, USED
GRACO 205395, 50:1 FIREBALL BARRELL 425 AIR PUMP, USED
MAGNETEK L717 GP+ 10 HP E PLUS ADJUSTABLE SPEED
RELIANCE ELECTRIC 3RA2002 SERVO DRIVE USED
TEST GUAGE CART – 3 GAUGES, 3 DRAWERS, USED
RELIANCE ELECTRIC 3RA2001 SERVO DRIVE USED
RELIANCE ELECTRIC 3RA2008U SERVO CONTROLLER USED
WESTINGHOUSE LD3600WK 600A CIRCUIT BREAKER USED
LIGHTNIN ND-4A MIXER, USED
AIR DRAULICS 10002510 CYCLINDER ,USED
VALMET PIC-200/100-170?-31488 SS PNEUMATIC CYLINDER, NEW
WESTINGHOUSE HKD3400F CIRCUIT BREAKER USED
VIKING HL4125 HYDRAULIC PUMP, 1 5/8x 11/16 SHAFT, USED
VON RUDEN 90-464 RATIO 1:1:1 GEAR BOX, USED
ROSEMOUNT ANALYTICAL pH MODEL 1003 UNILOC DIVISION,NEW
GENERAL ELECTRIC E10F2 1HP ELECTRIC MOTOR NEW
EFDYN MASA 2 X 6 PS HV 4598 SHOCK ABSORBER NEW
GENERAL ELECTRIC 5KC49PN0446X 1 HP ELECTRIC MOTOR, NEW
ELECTROMOTIVE SBPN-6-WH SWITCH NEW
RELIANCE ELECTRIC 3RA2004 SERVO DRIVE USED
ALLEN-BRADLEY 2192F-BJC-24J MOTOR CONTROL CTR UNIT USED
ALLEN-BRADLEY 2192F-BJC-24-11?0 MOTOR CTR UNIT USED
ALLEN-BRADLEY 2154B-AAB-38 MOTOR CTRL CTR USED
ALLEN-BRADLEY 2112B-BDBD-24J-?98-106-107 MOTOR CTRL CTR
ALLEN-BRADLEY 2112B-BDBD-1-4G?-24J-98-106-107 MOTOR CTR
WESTINGHOUSE JDB3225W 225A CIRCUIT BREAKER/JDB 25K USED
BOSTON GEAR 88KRF724-408-87?-J MOTOR USED
GENERAL ELECTRIC DS3827BS6 THYRISTOR, NEW
HYTROL 4AC 20-1 RH GEAR REDUCER NEW
KLOCKNER-MOELLE?R N 11-400-CNA CIRCUIT BREAKER USED
NIBCO WD-3110-0 VALVE NEW
FIFE CSP-01-06 ESU01 SENSOR USED
TOP TECH TT-E75-3SP2 3/4 HP ELECTRIC MOTOR , NEW
IDT PERIPHERAL CONTROL UNIT POWER SUPPLY USED
ALLEN-BRADLEY 2192F-D23444O/3?-2E MOTOR CTRL CTR USED
LOT OF 6 OMRON G3PA-210B SOLID STATE RELAYS, USED
ALLEN-BRADLEY 1771-AB CHASSIS/WITH MODULES USED
FASCO E2204 1/3 HP ELECTRIC MOTOR , NEW
GENERAL ELECTRIC L737BS 1/4 HP ELECTRIC MOTOR, NEW
RELIANCE/TIGEAR 7916130DB 1.39HP GEARMOTOR USED
GENERAL ELECTRIC L736CS 1/4HP MOTOR NEW
DODGE TIGEAR MR34619 1HP GEAR BOX, USED
NIHON SEIKI BN-6041-63-30L PNEUMATIC CYLINDER, NEW
EATON IDT 92-00314-09 UNIVERSAL PCU, USED
ALLEN-BRADLEY 2192F-U4-26J MOTOR CONTROL CTR UNIT USED
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RELIANCE ELECTRIC 3RA2002 SERVO DRIVE USED
HIMMELSTEIN 6-201 TRANSDUCER USED
ALLEN-BRADLEY 1771-P2 POWER SUPPLY USED
TELEMECANIQUE LB1 LB03P MOTOR STARTER USED
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KLOCKNER MOELLER DIL1M STARTER USED
ALLEN-BRADLEY 700-RTA10L100A1 RELAY USED
ALLEN-BRADLEY 1771-P2 POWER SUPPLY, USED
LOT OF 2/ LEVITON 2336 FLANGED OUTLET NEW
WESTINGHOUSE FD-K 100A CIRCUIT BREAKER USED
SHARK/RELIANCE ELECTRIC 45C922 SLOT RACK USED
WARNER ELECTRIC MC4 PRECISION TORK, USED
SMC NAQ5000 VALVE USED
SMC NAR825-N12 VALVE USED
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3 ALLEN-BRADLEY 1794-ASB FLEX I/O POWER SUPPLY, USED
SIEMENS 1P GES7 221-1EF00-0XA0 MODULE USED
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