IC693ACC303IC693ACC303

當CPU處理前臺任務時，USB的傳輸可在后臺進行；后臺中斷服務程序和前臺主程序循環之間的數據交換可以通過事件標志和數據緩沖區來實現。當PDIUSBD12從USB收到一個數據包，即對CPU產生一個中斷請求，CPU立刻響應中斷。在中斷服務程序中，固件將數據包從PDIUSBD12內部緩沖區移到循環數據緩沖區，并將PDIUSBD12的內部緩沖區清零，以便接收新的數據包，使CPU可以繼續執行當前的前臺任務直到完成。本文利用PDIUSBD12的端點1進行命令的傳輸和應答，端點1每次接收計算機發送過來的8 B指令，其指令格式如表2所示。例如，接收到十六進制碼52 01 00 03 00 07 00 50，表示讀24C01器件從03字節開始的7個字節的數據。52H為R的ASCII碼，57H為W的ASCII碼。端點2用于數據的傳輸。

PLC的發展趨勢
    隨著PLC應用領域日益擴大，PLC技術及其產品結構都在不斷改進，功能日益強大，性價比越來越高。

    （1）、在產品規模方面，向兩極發展。一方面，大力發展速度更快、性價比更高的小型和超小型PLC。以適應單機及小型自動控制的需要。另一方面，向高速度、大容量、技術完善的大型PLC方向發展。隨著復雜系統控制的要求越來越高和微處理器與計算機技術的不斷發展，人們對PLC的信息處理速度要求也越來越高，要求用戶存儲器容量也越來越大。
    （2）、向通信網絡化發展
    PLC網絡控制是當前控制系統和PLC技術發展的潮流。PLC與PLC之間的聯網通信、PLC與上位計算機的聯網通信已得到廣泛應用。目前，PLC制造商都在發展自己的通信模塊和通信軟件以加強PLC的聯網能力。各PLC制造商之間也在協商通用的通信標準，以構成更大的網絡系統。PLC已成為集散控制系統（DCS）*的組成部分。
 

鄭娟萍

廈門仲鑫航自動化設備有限公司  

 （3）、向模塊化、智能化發展
    為滿足工業自動化各種控制系統的需要，近年來，PLC廠家先后開發了不少新器件和模塊，如智能I/O模塊、溫度控制模塊和專門用于檢測PLC外部故障的智能模塊等，這些模塊的開發和應用不僅增強了功能，擴展了PLC的應用范圍，還提高了系統的可靠性。
    （4）、編程語言和編程工具的多樣化和標準化
    多種編程語言的并存、互補與發展是PLC軟件進步的一種趨勢。 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，日益向MAP(制造自動化協議)靠攏，使PLC的基本部件，包括輸入輸出模塊、通信協議、編程語言和編程工具等方面的技術規范化和標準化。

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