IC693ACC303IC693ACC303

當(dāng)CPU處理前臺(tái)任務(wù)時(shí)，USB的傳輸可在后臺(tái)進(jìn)行；后臺(tái)中斷服務(wù)程序和前臺(tái)主程序循環(huán)之間的數(shù)據(jù)交換可以通過(guò)事件標(biāo)志和數(shù)據(jù)緩沖區(qū)來(lái)實(shí)現(xiàn)。當(dāng)PDIUSBD12從USB收到一個(gè)數(shù)據(jù)包，即對(duì)CPU產(chǎn)生一個(gè)中斷請(qǐng)求，CPU立刻響應(yīng)中斷。在中斷服務(wù)程序中，固件將數(shù)據(jù)包從PDIUSBD12內(nèi)部緩沖區(qū)移到循環(huán)數(shù)據(jù)緩沖區(qū)，并將PDIUSBD12的內(nèi)部緩沖區(qū)清零，以便接收新的數(shù)據(jù)包，使CPU可以繼續(xù)執(zhí)行當(dāng)前的前臺(tái)任務(wù)直到完成。本文利用PDIUSBD12的端點(diǎn)1進(jìn)行命令的傳輸和應(yīng)答，端點(diǎn)1每次接收計(jì)算機(jī)發(fā)送過(guò)來(lái)的8 B指令，其指令格式如表2所示。例如，接收到十六進(jìn)制碼52 01 00 03 00 07 00 50，表示讀24C01器件從03字節(jié)開(kāi)始的7個(gè)字節(jié)的數(shù)據(jù)。52H為R的ASCII碼，57H為W的ASCII碼。端點(diǎn)2用于數(shù)據(jù)的傳輸。

PLC的發(fā)展趨勢(shì)
    隨著PLC應(yīng)用領(lǐng)域日益擴(kuò)大，PLC技術(shù)及其產(chǎn)品結(jié)構(gòu)都在不斷改進(jìn)，功能日益強(qiáng)大，性價(jià)比越來(lái)越高。

    （1）、在產(chǎn)品規(guī)模方面，向兩極發(fā)展。一方面，大力發(fā)展速度更快、性價(jià)比更高的小型和超小型PLC。以適應(yīng)單機(jī)及小型自動(dòng)控制的需要。另一方面，向高速度、大容量、技術(shù)完善的大型PLC方向發(fā)展。隨著復(fù)雜系統(tǒng)控制的要求越來(lái)越高和微處理器與計(jì)算機(jī)技術(shù)的不斷發(fā)展，人們對(duì)PLC的信息處理速度要求也越來(lái)越高，要求用戶存儲(chǔ)器容量也越來(lái)越大。
    （2）、向通信網(wǎng)絡(luò)化發(fā)展
    PLC網(wǎng)絡(luò)控制是當(dāng)前控制系統(tǒng)和PLC技術(shù)發(fā)展的潮流。PLC與PLC之間的聯(lián)網(wǎng)通信、PLC與上位計(jì)算機(jī)的聯(lián)網(wǎng)通信已得到廣泛應(yīng)用。目前，PLC制造商都在發(fā)展自己的通信模塊和通信軟件以加強(qiáng)PLC的聯(lián)網(wǎng)能力。各PLC制造商之間也在協(xié)商通用的通信標(biāo)準(zhǔn)，以構(gòu)成更大的網(wǎng)絡(luò)系統(tǒng)。PLC已成為集散控制系統(tǒng)（DCS）*的組成部分。
 

鄭娟萍

廈門(mén)仲鑫航自動(dòng)化設(shè)備有限公司  

 （3）、向模塊化、智能化發(fā)展
    為滿足工業(yè)自動(dòng)化各種控制系統(tǒng)的需要，近年來(lái)，PLC廠家先后開(kāi)發(fā)了不少新器件和模塊，如智能I/O模塊、溫度控制模塊和專(zhuān)門(mén)用于檢測(cè)PLC外部故障的智能模塊等，這些模塊的開(kāi)發(fā)和應(yīng)用不僅增強(qiáng)了功能，擴(kuò)展了PLC的應(yīng)用范圍，還提高了系統(tǒng)的可靠性。
    （4）、編程語(yǔ)言和編程工具的多樣化和標(biāo)準(zhǔn)化
    多種編程語(yǔ)言的并存、互補(bǔ)與發(fā)展是PLC軟件進(jìn)步的一種趨勢(shì)。 PLC廠家在使硬件及編程工具換代頻繁、豐富多樣、功能提高的同時(shí)，日益向MAP(制造自動(dòng)化協(xié)議)靠攏，使PLC的基本部件，包括輸入輸出模塊、通信協(xié)議、編程語(yǔ)言和編程工具等方面的技術(shù)規(guī)范化和標(biāo)準(zhǔn)化。

Ashcroft Model: 250-3074 Guage.  New Old Stock.  No Box  

Ashcroft Test Guage.  0 - 300 PSI. No Model Number  

Ashcroft Type 1008 316 SS Guage, 1/4" NPT, 63mm  

HPS MKS100312906-W NW50 AL CLAMP W/WASHER NEW  

Marsh:  J2440 General Service Gauge.  2.0 STB-B, 1/8M, 0/15 PSI.  New Old Stock 

MARSH J7654P 63MM SEVB 1/4 NPT 0-200PSI KPA GAUGE.  New Old Stock  

Ashcroft: 35-1009AW-02L-1000# General Service Guage.  New Old Stock 

Sensotec: 060-3147-01 GM Digital Display / Signal Conditioner, In Altered Box  

 Marshalltown Instruments Model: G23868 Press. Gauge.  New Old Stock  

Weiss Instruments: 9VU35 INDUSTRIAL GLASS THERMOMETER.  New Old Stock  *W2

Dwyer 3000 Series, Model: 3025 Photohelic Guage  

Sensotec / Honeywell Model: 060-H919-04.  Order Code: FPG2DN,2P5B6M  

Hydrocraft: HC1V-002S Liquid Filled Guage.  -30 in Hg to +30 PSI.  New Old Stk  

MKS Instruments Model: 621A Signal Conditioner.  PN: 621A11TBFH.  Genly Used  J 

Marsh / Bellofram: J4648 Guage. 2.5 STD, 1/4 NPT  

Custom Controls Sensor Inc. Model: 604P12 Pressure Switch.  3000 PSIG  

SENSOTEC 41/8750-04-02 LOAD CELL RANGE: 100 LBS 10.0 VDC  W

Viatran Model: 5715BCSTFYMZU Pressure Transmitter.  Range:  0 - 10000 PSI  W

Aschcroft Model: 25W1001TH 01B XUC Brass Guage.  2? Case.   New Old Stock    J

ROBERTSHAW UNI-LINE 2420-001 1 1/2" GAUGE QTY 2 NEW  

MKS Instruments Type: 600A Partial Pressure Transducer 

Pacific Scientific / Precision Model: G425FSD04S Guage.  New Old Stock   R   

Eugene Ernst Products / EEP: Clear No. 500 Standard Glass Guage.  New Old Stock 

Wika: 0 - 10,000 PSI Liquid Filled Gauge.  316 SS Tube and Connection.   No PN  

NoShok Model: 25.120.100. PSI.FPT.? NPT  Control Guage.  New Old Stock 

Ametek / USG Model: 70MDD  Pressure Guage.   New Old Stock  

T-Hydronics: TH-MF Pressure Transducer.  P/N: 005168-7.  Range: 0-7500 PSIG   W

Process Level Technology MAG-GAGE, MG with Float and  MGS-500EX   

MKS Instruments: 122AA-00001AB Pressure Transducer 

MARSHALL TOWN GG-25100 L4 GG25100L4 100PSI 1/2" GUAGE  

Patriot 65998-SP100-9410000G Pressure Transducer.  0 - 10000 PSIG.  Used  

Sensotec Model: AG-200, P/N: 060-9965-23 ACCU-GAGE Controller   W

Matheson Regulator Assembly w/ 4384 and 3455 Valves  

MKS / Baratron: 122A-11063  Pressure Transducer.  10 TORR.  Input:  +/- 15VDC  

2-1/2" DRY 1/2 NPT BRASS LOWER 0-100 PSI/KPA/BAR GUAGE 

MKS / HPS Products Model: V-100-IM-MR-NV Valve.  Nw100 Valve   

Dillon Quantrol Smart S-Beam.  Part Number: 49753-0055. Capacity: 550 lbf   W

SENSOTEC 41/8937-01-01 LOAD CELL RANGE 10000 LBS 10.0 VDC   W

ASHCROFT 25W1001TH 01B XUC PANEL MOUNT GAUGE NEW  

MKS / HPS Division Model:  NW50 AL Clamp w/ Washer  

WEKSLER MODEL: BY12YPT4LW Pressure Gauge 2.5" (New Old Stock) *

(8) SPAN / TYLAN 0-4000 PSI Pressure Gauge, new =

SI Span Instruments: IPS122 Press. Guage w/Control Box 

Kulite Semiconductor: HKS-375-5000SG  Pressure Transducer.   Unused. Short Wire 

Marshalltown Instruments: Y1211 Industrial Thermometer.    New Old Stock  

Viatran Model: 5715BCSNHTFYAZU  Pressure Transmitter.  Range:  0 - 3000 PSI  W

Viatran Model: 5715BH6X2960 Pressure Transmitter.  Range:  0 - 7500 PSI  W

SENSOTEC Z/8809-03 20000 PSIG 10.0 VDC 2.9 MV/V   W

Sensotec Model: 060-6831-00 Load Cell.   W

MKS / Baratron: 122B-14670  Pressure Transducer 

Entran Model: ELF-500-56B-5, "EL Type" Load Cell  

ASHCROFT 8080000 THERMOMETER 8544-152 60 TO 260 F DRESSER IND TYPE A AISLE BB  

2.5" Dry, 1/4 NPT, Brass Pressure Guages NEW 

MKS Instruments Model 652B-DD  Exhaust Throttle Valve.   

Honeywell Sensotec P/N: 060-K107-01 Non-Aplified Transducer.  Model: WPK  W

Kulite Semiconductor: BME-1100-1000A-A-4-1 Pressure Transducer.  New Old Stock  

Victor Supply Company Model:  SR250D Welding Guage   

Kulite Semiconductor: HKS-375-5000SG  Pressure Transducer.  New Old Stock  

WIKA TYPE: 213.53 2.5 1000PSI 9767126 1/2" GUAGE.  New Old Stock   

Viatran Model: 345BHGCMX251 Pressure Transducer w/ Cable.  Range: 0-7500 PSIG  W

Leeds & Northrup: 2610-100-12-2-01-300-802-809 Pressure Transmitter. New Old Stk

Ashcroft Test Guage, Temerature Compensated. No Mdl #  

Interface LBM Compression Load Button Model: LBM-5K with TEDS Installed   

Interface LBM Compression Load Button Model: LBM-10K-468 with TEDS Installed   

Interface LBM Compression Load Button Model: LBM-20K with TEDS Installed   

Aschcroft Industrial Duralife Gauge, Type: 1009. New Old Stock  

MKS Instruments Type: TC-1A Thermocouple Vacuum Guage  

MKS Instruments Type: TC-1A Thermocouple Vacuum Guage  

MKS / HPS Model: 162-0016T Standard Pneumatic Single Stage Unheated Valve  W2 

Marsh: J4020 Guage.  2.5 STD 1/8" NPT.  30X 300 INHGXPSI & KPA.  New Old Stock  

Transducer Techniques Model: DPM 3  Control Panel  W2

Transducer Techniques Model: DPM-3 Plug & Play,Control Panel.  IEEE 1451.4  W2

Wika: 232.53 Guage.  P/N: 9768327.  2.5", 100PSI, ?" CBM/FF.  New Old Stock   

Kulite Semiconductor XTS-1-190-2000A Press. Transducer.  New Old Stock  

MKS Instruments Model 244C-1-VP0 Pressure/Flow Cntlr.

MKS / Baratron: 127AA-000.1C Pressure Transducer.  1 TORR.  Input:  +/- 15VDC  

Datametrics Barocel Pressure Sensor, PN: 600A-10T-R12- 

Ashcroft Model: 601010A-04L 0/15#  & 0/100 General Service Guage.  ? NPT Lower W

Transducer Techniques: LBO-30K Low Profile Compression Load Cell.  30K Lbs  

McDaniel Controls FGI Glycerin Filled Pressure Guage  

LDS SC-7C WHITEY 10EK907 5.55 X 10-7 ATM HELIUM LEAK  

LDS SC-7C WHITEY 10EK907 5.91 X 10-7 ATM HELIUM LEAK  

Winter's 0 - 100 PSI & KPA Code 904 Guage.  2.5 X ? NPT.  New Old Stock 

T-HYDRONICS MODEL: A005168-7.5K PRESSURE TRANSDUCER *W2

Dwyer Cat. 2-5001 Minihelic II Differential Pressure Guage.  Cat. #:  N23T   W

Dwyer Cat. N44K Minihelic II Differential Pressure Guage.   W

Magnehelic: 2002C Pressure Guage.  0 - 2 Inches of Water.  15 PSIG Max. Press  W

Eugene Ernst Prod. / EEP: Clear No. 500 Std Glass Guage.  OD: 8?. New Old Stock 

Ashcroft Model: 12D Metal Case Thermometer.  50 - 300° F.  New Old Stock No Bo 

MKS Baratron Model: 122BA-00100DB Pressure Transducer 

(2) DWYER series 1800 Pressure Switch, new =

Omega Engineering Model: PX602 Thin Film Pressure Sensor   W2

WIKA 8610007 3133890 TRANSMITTER S-10 17955838 NEW   

AMETEK P844U PRESSURE GAUGE 30 PSI NEW IN BOX  

Omega Engineering Model: PIX314-050A5V General Pressure Transmitter   W

Spir Star: 5/4HT High Pressure Hose.  1.5 Feet, Max PSI: 15000. 1/4 NPT Male   W

Viatran Model: 345BPSDNYM Pressure Transducer.  Range: 0-15000 PSIG 

Heise / Dresser Model: CMM-125153 0 - 10,000 PSI Test / Pressure Guage  W

Cronatron CW2004 Heavy Duty 2 Stage Press. Reg. New   

SI SPAN INSTRUMENTS IPS 122 TYPE 1 GUAGE 12 WATT NEW  

Druck Model PTX 510 Pressure Transducer.  5000 PSI, 9 - 30Vdc 

Rosemount Model: 3051 Pressure Transmitter.  TA3A2B21AB4E8M5Q4.  800PSIA.    W2

STANDARD METER LAB LFE: AH-0103-0000 O204 LASER GUAGE  

STANDARD METER LAB LFE: AH-0103-0000 O204 PHOTOCURRENT 

AMETEK DUPONT S2204 FILTER KIT QTY (5) NEW  

MKS PARTIAL PRESSURE TRANSDUCER TYPE 600A PPT-1A-100FC 

Marshalltown Instruments: G10172. Gauge.  4?,  ? Bottom Conn.  New Old Stock  

Marsh Model: J7220RP GAUGE *W2

Sensotec:  060-6827-04 Inline Amplifier.  Input: 18-28V DC.  Out: +/- 10 VDC   

Weiss Instruments: LF25S-1 Glycerine Filled Gauge.  

BS&S Safety Systems Ruture Disk (Bursting Disc), P/N: CH-0-000-2-000.    W

MKS / Baratron: 122B-14670  Pressure Transducer 

NoShok Model: 25.400.1500 PSI 1/4 Bottom Control Guage.  New Old Stock 

UTHE Technology:  27PT  Standard Wedge Transducer.  Freq: 64.0.  New Old Stock 

Kulite Semiconductor: BME-1100-1000A-A-X-1 Pressure Transducer.  New Old Stock  

Numatics Model: 214-194 Liquid Filled Pressure Guage.  New Old Stock.   

MKS Type 247C Instruction Manual, PN: 195-110354A-7/87 

Ametek / USG Model: 146002 Pressure Guages. 60 PSI, 1/8 NPT,  New Old Stock  

BRC Model: W101 4" Gauge   

Victor Model:  SR4K Inert Gas Weld Gauge.  5500 PSIG.  Good Used Stock    

Rosemount Model: 1151DP3E22  Pressure Transmitter.  Spares Unused Old Stock   

TRANE AMETEK GAG 0105 GAG0105 1000PSI 153619 GAUGE  

Viatran Model: 571AZ2ZSTFYA2U Pressure Transmitter.  Range:  0 - 1500 PSI  W

MKS / NGS  PPT Residual Gas Analyzer, PPT-1A-100FC 

ASHCROFT 20W1005 Steel Polycarbonate Brass Gauge.   New Old Stock  

Ashcroft Model: 1001 XUC Guage, 1/4" NPT  

Ametek 1980 Pressure Guage.  New in box

MKS Instruments Model: 919 Hot Cathode Controller  

MKS Instruments: 227AA-00001-SPFTG-8VCO  Transducer 

Sensotec Model: AG-200, P/N: 060-9965-23 ACCU-GAGE Controller Good Used Stock  

Helium Leak Testing, Inc / QHe Model: HLT-7DT Leak Detector.  S/N: 2386  

Helium Leak Testing, Inc / QHe Model: HLT-7DT Leak Detector.  S/N: 2387  

Helium Leak Testing, Inc / QHe Model:  0981  Leak Detector.  S/N:  LLE9027  

Pressure Transducer: GP:50 Pressure Transducer.  Part #: 311-B. 0 - 20 PSIV  

MKS Instruments: 227AA-00001A Pressure Transducer 

Helium Leak Testing, Inc / QHe Model:  SC-8D  Leak Detector.  S/N:  EBBB6007  

Helium Leak Testing, Inc / QHe Model:  SC-8D  Leak Detector.  S/N: 8836  

Western Accu-Trol Model: RHP-2-4 Compressed Gas Regulator    

DC MILLIAMPERES 0-1 2031-4842001 GAUGE PLASTIC NEW