IC693ACC302IC693ACC302
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。
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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。
Honeywell Model: VP531A10205 Pneumatic Unitary Valve
Bank of 2 Numatics Model 08RS100J w/ Flexiblok
Turn-Act Val-U-Act Model: VA-00-21-3-000 Value Operator Valve
Numatics: 3FC2 Inline Aluminum 3/8" Flow Control Valve. New Old Stock. No Box
Koganei Model: CS9HA Sensor
Lot of Humphrey Model: 8-D2EV-1/2 Pneumatic Cylinders. Qty. 2. New Old Stock
Fastenal Model: 442065 Seal Union, 1/4 ODX 1/4 NPT. New Old Stock
Pisco Tube Model: N434UQ04-011 Flat Pneumatic Tube. New Old Stock
Clippard Model: 3BDS-4 Brass Cylinder. New Old Stock
NORGREN S-33016 MOSIER AIR VALVE USED
SMC Model: NCDA1B200-0300 Pneumatic Cylinder. 2IN. Bore, 3In Stoke W
SMC Model: NCDA1B200-0200 Pneumatic Cylinder. 2IN. Bore, 2In Stoke W
SMC Model: NCDA1B200-0600 Pneumatic Cylinder. 2IN. Bore, 6In Stoke W
Humphrey Model: 8-DB-3/4 Pneumatic Cylinder. New Old Stock H
Humphrey Model: 7-D-2 5/8 Pneumatic Cylinder. New Old Stock H
Fabco-Air Model: E-5-XDR Cylinder. New Old Stock
Humphrey Model: 7-D-2 Pneumatic Cylinder. New Old Stock H
Humphrey Model: 7-D2EY-1 Pneumatic Cylinder. New Old Stock H
Humphrey Model: 7-D-5 Pneumatic Cylinder. New Old Stock H
SINGER 239A 140/290 #L 7/8 125 G 239-191 REGULATOR NEW
Humphrey Model: 8-DP-3 ? Pneumatic Cylinder. New Old Stock H
SMC Model: MGCLB50-125-R-XC18 Pneumatic Cylinder. *W
SMC Pneumatics Model: CDUK20-30D with Two SMC D-97 Sensors O
Precision Dynamics Model: G3114 Solenoid Valve. 24VDC, .65W & 40 MOPD
Arrow Pneumatics Model: F300-02 Air Water Seperator. New Old Stock. No Box
Angar Scientific Model: 409214 Solenoid Valve. 24VDC, 60 PSI
Angar Scientific Model: 409220 Solenoid Valve. 24VDC, 60 PSI
Brunswick / Technetics Model: 409214 Solenoid Valve. 24VDC, 60 PSI
Humphrey Model: 6-D-5 Pneumatic Cylinder. New Old Stock H
Humphrey Model: 8-D2EY-1 Pneumatic Cylinder. New Old Stock H
Numatics Model: 081SS500M000061 Solenoid Valve. 24 VDC, .26A, 150 PSIG Air W
Numatics Model: 082SA415M Solenoid Valve. 24 VDC, .26A, 150 PSIG Air W
SMC Model: NCDA1B150-1000 Pneumatic Cylinder. 1IN. Bore, 10In Stoke W
Numatics Model: 081SS400M1 Solenoid Valve. 24 VDC, .26A, 150 PSIG Air W
SMC Cylinder Model: ZSE30-01-65 PRESSURE Switch * W
Numatics Model: 031RD700O Pull-To-Adjust Manifold Valve W
SMC Model: SS5Y5-42-02-02T Fitting. *W
Numatics Model: 081SA400M Valve Mounted to Manifold
SMC Cylinder Model: CDQ2A50-10DM Cylinder/ Actuators *W
Numatics FlexiBlok with: (3) 082SA415M Valves and Two Filters on Manifold
SMC Model: NCDQ2A20-50DM Cylinder/ Actuator
NUMATICS: 152SS602M000061 SOLENOID VALVE W/ (2) 225-372B W2
Numatics: 153SS43AM000061 Solenoid Valve Ass'y w/ (2) 225-372B & Manifold W2
SMC Model: NAMC 310 Exhaust Cleaner W
Lot of Kuroda PCC235-NB-D24**, 24V DC Valves, Qty. 2. Unused Old Stock
Bank of Predyne 3D2016 Valves Mount to Brass Plate
SMC Cylinder Model: NCME125-0200 Cylinder.
Fabco-Air "The Pancake Line" Model: F-721-X Round Cylinder
Numatics Mdl: L01SA4594 Cylinder w/226-127B Manifold
SMC Model: MGCLB20-100 Pneumatic Cylinder. *W
Numatics Model: M11SA441M000060 Air Operated Solenoid Valve. 12VDC, 1.8W
Bosch Rexroth Model: 0-842-900-300 Latch Stop Gate
Parker Model: XR057-370FT-AP23M-A Rotary Actuator
Clippard Minimatic: 18D-9 1 1/8" Bore Heavy Duty Cylin
Humphrey Model: 7-D-? Pneumatic Cylinder. New Old Stock H
Parker: XR057-370FT-AP23M-A Rotary Actuator, Used
Humphrey Model: 8-D2EY-? Pneumatic Cylinder. New Old Stock H
SMC Model: MGPL40N-50 Pneumatic Cylinder. *W
Parker Model: D1VW4CNYCF 72 Control Valve with Parker D61VW1C4NYCF 72
Humphrey Model: HJDAS 50 X 4 4" Stroke Air Cylinder
Fabco-Air Model: J7X "Mini Pancake" Cylinder
Numatics Flexiblok with 081SA4004011Z61 + 225-239B
Lot of Compact Air Products Valve, 5. See List Below
Barry Controls SLM-6A High Capacity Mount, STABL-LEVL
Plasmatech TFE Teflon Fitting Model: 02F6S28
MASTER PNEUMATIC MRS100 Silencer Re-clas-sifier, =
Ross Model: 2773A4075 Solenoid Lockout Valve w/ Norgren Quietaire Muffler
The Mack Corporation Model: 630-2 Low Profile Actuator
SMC Cylinder Model: CDQ2A80-25DM-F7, PWZ Cylinder/ Actuators *W2
SMC Pneumatics Model: AW111 Relief Regulator w/ Guage
American Cylinder: 437DVS-2.00 Cylinder. 7/16" Bore, 2" Stroke. New Old Stk
SMC Pneumatics Model: VT301-V Solenoid Valve.
Numatics Model: 236-384B Two Directional Air Valve. K
Bosch Model: 0820402046 Pneumatic Directional Valve. Gently Used
SMC Model: NCDA1R200-0500 Pneumatic Cylinder. * W2
Lot of Barnes Distribution: KP23980 Push-To-Connects. Qty. 5. New Old Stk
SMC Pneumatics Model: AR20-N02-Z Pneumatic Air Regulator with Gauge
Humphrey Model: HA180-4E1 Solenoid Valve
Lot of Camozzi 1511 Push On Fittings-Male Studs. 3/8" Thread. Qty. 10. New O
SMC: Model: NVFS4300-5FZ Pilot Solenoid, 20 - 145 PSI
Rexroth Pneumatik Model: 572-400-747-0 Solenoid. 115V. New Old Stock. No Box
SMC Cylinder Model: NCGBN20-0100 Cylinder. New Old Stock
SMC: Model: NARBF4000-A Interface Regulator w/ Guage. 7 - 145 PSI
SMC Model: NCDA1B200-1000. 2IN. Bore, 10In Stoke w/ SMC NJ07 Joint Float
SMC Model: NCDA1B150-600 Cylinder with SMC NJ07 Joint Float
Humphrey Model: 3E1 24V DC Air Solenoid. Used Gently
Lot of Pisco Model: POC4-M5M Push In Fittings. Qty. 10. New Old Stock.
