IC693ACC302IC693ACC302
当CPU处理前台任务时，USB的传输可在后台进行；后台中断服务程序和前台主程序循环之间的数据交换可以通过事件标志和数据缓冲区来实现。当PDIUSBD12从USB收到一个数据包，即对CPU产生一个中断请求，CPU立刻响应中断。在中断服务程序中，固件将数据包从PDIUSBD12内部缓冲区移到循环数据缓冲区，并将PDIUSBD12的内部缓冲区清零，以便接收新的数据包，使CPU可以继续执行当前的前台任务直到完成。本文利用PDIUSBD12的端点1进行命令的传输和应答，端点1每次接收计算机发送过来的8 B指令，其指令格式如表2所示。例如，接收到十六进制码52 01 00 03 00 07 00 50，表示读24C01器件从03字节开始的7个字节的数据。52H为R的ASCII码，57H为W的ASCII码。端点2用于数据的传输。
PLC的发展趋势
随着PLC应用领域日益扩大，PLC技术及其产品结构都在不断改进，功能日益强大，性价比越来越高。
（1）、在产品规模方面，向两极发展。一方面，大力发展速度更快、性价比更高的小型和超小型PLC。以适应单机及小型自动控制的需要。另一方面，向高速度、大容量、技术完善的大型PLC方向发展。随着复杂系统控制的要求越来越高和微处理器与计算机技术的不断发展，人们对PLC的信息处理速度要求也越来越高，要求用户存储器容量也越来越大。
（2）、向通信网络化发展
PLC网络控制是当前控制系统和PLC技术发展的潮流。PLC与PLC之间的联网通信、PLC与上位计算机的联网通信已得到广泛应用。目前，PLC制造商都在发展自己的通信模块和通信软件以加强PLC的联网能力。各PLC制造商之间也在协商通用的通信标准，以构成更大的网络系统。PLC已成为集散控制系统（DCS）*的组成部分。
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厦门仲鑫航自动化设备有限公司
（3）、向模块化、智能化发展
为满足工业自动化各种控制系统的需要，近年来，PLC厂家先后开发了不少新器件和模块，如智能I/O模块、温度控制模块和专门用于检测PLC外部故障的智能模块等，这些模块的开发和应用不仅增强了功能，扩展了PLC的应用范围，还提高了系统的可靠性。
（4）、编程语言和编程工具的多样化和标准化
多种编程语言的并存、互补与发展是PLC软件进步的一种趋势。 PLC厂家在使硬件及编程工具换代频繁、丰富多样、功能提高的同时，日益向MAP(制造自动化协议)靠拢，使PLC的基本部件，包括输入输出模块、通信协议、编程语言和编程工具等方面的技术规范化和标准化。
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.
