描述
FCS的关键要点有三点
(1)FCS系统的核心是总线协议,即总线标准
前面的章节已经叙述,一种类型的总线,只要其总线协议一经确定,相关的关键技术与有关的设备也就被确定。就其总线协议的基本原理而言,各类总线都是一样的,都以解决双向串行数字化通讯传输为基本依据。但由于各种原因,各类总线的总线协议存在很大的差异。
为了使现场总线满足可互操作性要求,使其成为真正的开放系统,在IEC国际标准,现场总线通讯协议模型的用户层中,就明确规定用户层具有装置描述功能。为了实现互操作,每个现场总线装置都用装置描述DD来描述。DD能够认为是装置的一个驱动器,它包括所有必要的参数描述和主站所需的操作步骤。由于DD包括描述装置通信所需的所有信息,并且与主站无关,所以可以使现场装置实现真正的互操作性。
实际情况是否如上述一致,回答是否定的。目前通过的现场总线国际标准含8种类型,而原IEO国际标准只是8种类型之一,与其它7种类型总线的地位是平等的。其它7种总线,不论其市场占有率有多少,每个总线协议都有一套软件、硬件的支撑。它们能够形成系统,形成产品,而原IEC现场总线国际标准,是一个既无软件支撑也无硬件支撑的空架子。所以,要实现这些总线的相互兼容和互操作,就目前状态而言,几乎是不可能的。
通过上述,我们是否可以得出这样一种映象:开放的现场总线控制系统的互操作性,就一个特定类型的现场总线而言,只要遵循该类型现场总线的总线协议,对其产品是开放的,并具有互操作性。换句话说,不论什么厂家的产品,也不一家是该现场总线公司的产品,只要遵循该总线的总线协议,产品之间是开放的,并具有互操作性,就可以组成总线网络。
产品承诺:
保 证 全新原装进口,
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主营DCS系统配件
机器人系统配件
大型伺服系统配件
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YORK ROTARY SCREW COMPRESSOR W/YORK ISN CODEPAK
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-24-110 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-MOELLER 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
E G D MFG SS20 2×2 INDL SHOCK ABSORBER CYLINDER, NEW
ALLEN-BRADLEY 160-BA01NSF1P1 STARTER USED
ALLEN-BRADLEY 1771-ARC REMOTE I/O ADAPTER MODULE
LOT OF 4/ OMRON D4A-2501N LIMIT SWITCH USED
INDUSTRIAL CONTROL CFM61 SWITCH NEW
HBM PLC-XX200 LOAD CELL, NEW*
GE DS3820HSM HEAT SINK, NEW
WESTINGHOUSE JDB3225W CIRCUIT BREAKER USED
ACOPIAN A24MT350 DC POWER SUPPLY USED
RELIANCE ELECTRIC 3RA2002 SERVO DRIVE USED
RELIANCE ELECTRIC 3RA2002 SERVO DRIVE USED
HIMMELSTEIN 6-201 TRANSDUCER USED
ALLEN-BRADLEY 1771-P2 POWER SUPPLY USED
TELEMECANIQUE LB1 LB03P MOTOR STARTER USED
LOT OF 2/ ALLEN-BRADLEY 509-B0D STARTER USED
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
SMC VP7-8-FG-S VALVE USED
3 ALLEN-BRADLEY 1794-ASB FLEX I/O POWER SUPPLY, USED
SIEMENS 1P GES7 221-1EF00-0XA0 MODULE USED
SIEMENS 1P GES7 222-1EF00-0XA0 MODULE USED
SMC RSH50-30BL CYLINDER NEW
VERSA VIS-2302 PNEUMATIC VALVE, NEW
SMC NVFS2200-1F PNEUMATIC VALVE, NEW
SMC NVFS2100-5FZ PNEUMATIC VALVE, NEW
SMC NVS4114-0009D PNEUMATIC VALVE, new
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SMC VFS2200-5FZ PNEUMATIC VALVE,NEW
SMC NVFS2100-1F PNEUMATIC VALVE, NEW
NORGREN S-A03205C CYCLINDER USED
PIAB XLC60 3301044 VACUUM PUMP,USED
SMC XTO-1239 VALVE NEW
ABB GCB0432 R2 DRIVE USED
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