西門子的S7-200的程序結構
過程映像輸入/輸出（I/Q）、變量存儲器V、內部存儲器位M、定時器T、計數(shù)器C等屬于全局變量。S7-200的程序組織單元(ProgramOrganizationalUnit，簡稱為POU)包括主程序、子程序和中斷程序。每個POU均有自己的64字節(jié)局部變量，局部變量只能在它所在的POU中使用。與此相反，全局變量可以在各POU中使用。
下面是子程序可以使用的局部變量：
1)TEMP(臨時變量)是暫時保存在局部數(shù)據(jù)區(qū)中的變量。只有在執(zhí)行該POU時，定義的臨時變量才被使用，POU執(zhí)行完后，不再保存臨時變量的數(shù)值。
2)IN是由調用它的POU提供的輸入?yún)?shù)。
3)OUT是返回給調用它的POU的輸出參數(shù)(子程序的執(zhí)行結果)。
4)IN_OUT是輸入_輸出參數(shù)，其初始值由調用它的POU傳送給子程序，并用同一變量將子程序的執(zhí)行結果返回給調用它的POU。
主程序和中斷程序的局部變量中只有臨時變量TEMP。
具有輸入、輸出參數(shù)和局部變量的子程序易于實現(xiàn)結構化編程，對于長期生產(chǎn)同類設備或生產(chǎn)線的廠家尤為有用。這些廠家的編程人員為設備的各組件或工藝功能編寫了大量的通用的子程序。即使不知道子程序的內部代碼，只要知道子程序的功能和輸入、輸出參數(shù)的意義，就可以通過程序之間的調用快速“組裝”出滿足不同用戶要求的控制程序。就好像用數(shù)字集成電路芯片組成復雜的數(shù)字電路一樣。
子程序如果沒有輸入、輸出參數(shù)，它和調用它的程序之間沒有清晰的接口，很難實現(xiàn)結構化編程。
子程序如果沒有局部變量，它和調用它的程序之間只能通過全局變量來交換數(shù)據(jù)，子程序內部也只能使用全局變量。將子程序和中斷程序移植到別的項目時，需要重新統(tǒng)一安排它們使用的全局變量，以保證不會出現(xiàn)地址沖突。當程序很復雜，子程序和中斷程序很多時，這種重新分配地址的工作量非常大。
如果子程序和中斷程序有局部變量，并且它們內部只使用局部變量，不使用全局變量，因為與其他POU沒有地址沖突，不需作任何改動，就可以將子程序移植到別的項目中去。
IDEC IZBARL IBRC-6012R RELAY BARRIER 16VDC 14mA 250VAC
G79601 Shimadzu SCL-10AVP HPLC System Controller
Enlarge
Shimadzu HPLC System: Freight/ Ground Shipping Possible
SHIMADZU VP HPLC DETECTOR AUTOSAMPLER CHROMATOGRAPH
Shimadzu SCL-10A VP System Controller
Shimadzu SPD-M10Avp HPLC UV/VIS Diode Array DAD
Shimadzu UV-1201 UV-Vis Spectrophotomet?er UV1201
Shimadzu SIL-10A XL HPLC Autosampler
Shimadzu HPLC System: Freight/ Ground Shipping Possible
Shimadzu 10A & VP Series DAD HPLC System
Shimadzu SCL-10A VP System Controller S-R
Shimadzu UV-Visable Recording Spectrophotomet?er UV160U
Shimadzu SPD-10A(vp) Prep Flow Cell
Shimadzu Liquid Chromatograph LC-4A 115VAC 10A 50/60 HZ
Shimadzu RF-540 Spectrofluoroph?otometer & DR-3 Recorder
Shimadzu SCL-10A HPLC System Controller Lab Waters S-R
SHIMADZU MODEL LC-6A LIQUID CHROMATOGRAPH Unit Used
Shimadzu UV-260 UV/VIS Doublebeam-Spec?trometer UV-260
Shimadzu LC10-AT VP HPLC Pump Liquid Chromatograph
Shimadzu LC10-AT VP HPLC Pump Liquid Chromatograph
Shimadzu TMP2003LMC turbo pump
turbo pump, AMAT pump,
SHIMADZU MODEL LC-6A LIQUID CHROMATOGRAPH
Shimadzu SCL-10A System Controller HPLC VP SCL10A LC UV
SHIMADZU UV1601 SPECTROPHOTOMET?ER TESTED
SHIMADZU LC-600 DUAL PUMP LIQUID CHROMATOGRAPH
Shimadzu Chromatograph LC-10AD CDD-6A SCL-10A SIL-10A
SHIMADZU GC17AAF WITH FID DETECTOR SOLD AS IS
Shimadzu SIL-10A Syringe Auto Injector HPLC Cooler Rack
Shimadzu SCL-10A System Controller
Expedited shipping available
Shimadzu Total Organic Carbon Analyzer TOC-4000
MOUNTING BRACKET FOR SHIMADZU AOC AUTOSAMPLER TRAY
Shimadzu FRC-10A Fraction Collector S-R
Shimadzu LC-10AD vp SCL-10A vp FCV-14AH Subcontrol LOT
Shimadzu Flame Photometric Detector
Shimadzu AA680U Atomic Absorption Flame Emission Spec
Shimadzu SIL-10A AutoInjector Autosampler LC SCL 10A VP
SHIMADZU SCL-10A SYSTEM CONTROLLER # 3219
Shimadzu Syringe Pump SIL-10A Auto Injector HPLC LC VP
Shimadzu SCL 10-A System Controller S-R
G79602 Shimadzu LC-10ADVP HPLC Liquid Chromatograph
Enlarge
Shimadzu FCV-10-AL-VP Low Pressure Gradient Valve S-R
Shimadzu UV-160U UV-VIS Recording Spectrophotomet?er
G79603 Shimadzu DGU-14A HPLC Degasser
Enlarge
Shimadzu VP Series HPLC
Shimadzu UV-2101PC Scanning Spectrophotomet?er UV2101PC
Includes CPS-260 Cell Positioner
G79604 Shimadzu 228-34736-91 Reservoir Tray
Enlarge
Shimadzu LC10-AT VP HPLC Pump Liquid Chromatograph
SHIMADZU SCL-6B System Controller Chromatograph HPLC
Shimadzu AA680U Atomic Absorption Flame Emission Spec?
Enlarge
SHIMADZU UV-VISIBLE RECORDING SPECTROPHOTOMET?ER
Shimadzu IR-460 DR-11 Cat No 204-08700-01 U-S
Shimadzu LC10-AT VP HPLC Pump Liquid Chromatograph
Shimadzu SIL-10AP AutoInjector SIL-10A Autosampler LC
Shimadzu Auto Injector SIL-6B w/ SCL-6B System Control
SHIMADZU TOC-5000 Total Organic Carbon Analyzer
with Data System-- Tested-Working?-Guaranteed!
One-day shipping available
Enlarge
Shimadzu LC-10ADvp HPLC Pump
Shimadzu RF-535 Fluorescence Detector HPLC Monitor
SHIMADZU MODEL LC-6A LIQUID CHROMATOGRAPH
Shimadzu RF-551 Spectrofluorome??tric Detector
Shimadzu SIL-10AXL autoinjector,sy?ringe pump, FCV-10AL
Shimadzu Spectrophotomet?er DR-15 RF-5000u
SHIMADZU UV-1601 PC UV-VISIBLE SPECTROPHOTOMET?ER
Shimadzu GC-14A GAS CHROMATOGRAPH USED SPL FID install
Shimadzu HPLC HDU-1 Liquid Chromatograph
SHIMADZU RACK FOR SIL-10ADVP (AND OTHER) AUTOSAMPLER
Shimadzu FCV-10AL Degasser Pump Unit Used
Shimadzu UV160U Recording Spectrophotomet?er UV-160U
Shimadzu LC10-AT VP HPLC Pump Liquid Chromatograph
SHIMADZU XRD-6000 X-RAY DIFFRACTOMETER NICE
SHIMADZU UV-160 UV VISIBLE RECORDING SPECTROPHOTOMET?ER
Shimadzu CTO -6A Column Oven HPLC Lab Use
Shimadzu SCL 10A HPLC System Controller
Shimadzu SIL-10A HPLC Auto Injector Sampler Cooler Rack
SHIMADZU SPD-6AV UV-VIS SPECTROPHOTOMET?RIC DETECTOR
SHIMADZU LC-600 LIQUID CHROMATOGRAPH
SHIMADZU UV-1601 PC SPECTROPHOTOMET?ER W/ CPS 240A
Nice Shimadzu CTO-10ASVP CTO-20AS VP Column Oven
Make me an OFFER-I have other Shimadzu Equipment listed
Enlarge
Shimadzu Visable Recording Spectrophotomet?er UV-160U
SHIMADZU RF-530 SPECTROFLUOROPH?OTOMETER MONITOR
Shimadzu HPLC cooler cooling unit sample
GC Shimadzu Split/Splitless Liner 5 pk Restek 20956-213
Shimadzu LC-10AT Liquid Chromatograph HPLC Flow Pump
SHIMADZU AUTO INJECTOR MODEL# ADC-17!
Shimadzu PC-12D-A Assy Board, 222-00978-92, ST3-15-8
Shimadzu TOC-5000A Total Organic Carbon Analyzer
?Shimadzu RF-1501 Spectrophotomet?er Micro oly wil█Fluor
Shimadzu Centrifugal Particle Size Analyzer SA-CP3
Shimadzu GC-14A All Purpose Gas Chromatograph System
Shimadzu Sipper 160 With Accessories And Carry Case
Shimadzu FRC-10A Fraction Collector for HPLC
Shimadzu TCC-240A Temperature Controller
LOT OF 2 SHIMADZU CONTROLLERS MODEL# CFC-14PM!
Shimadzu ELECTROCHEMICAL DETECTOR HPLC L-ECD-6A
Shimadzu Liquid Chromatography Pump Model LC-6A
Shimadzu RF-551 PC Spectrofluorome?tric HPLC Detector
Shimadzu RF-535 Fluorescence Detector HPLC
RF5301PC Shimadzu Spectrofluoroph?otometer 381 hours use
SAVE $14,000 Includes Computer, Flow Thru HPLC cell
Shimadzu HPLC degasser degassing unit degas DGU-3A
Shimadzu RF-535 Lab HPLC Monitor Fluorescence Detector
Shimadzu SCL-10A System Controller
SHIMADZU SPECTROPHOTOMET?ER UV-160
Altex Shimadzu 901 HPLC Chromatograph Integrator
Shimadzu SIL-HTa LC Autosampler SILHTa SILHTc HTc HT
Shimadzu UV-160 Spectrophotomet?er CPS-260 Controller Z
Shimadzu SIL-2A AutoSampler SIL-2AS Control Unit Used
SHIMADZU LC-600 Dual Pump HPLC Liquid Chromatograph
Shimadzu UV-260 UV-Visible Recording Spectrophotomet?er
Shimadzu SCL-6B System Controller
Shimadzu SIL-10AF Autosampler
SHIMADZU SCL-6A DETECTOR WITH AUTO INJECTOR SIL-6A
Shimadzu SPD 6A UV Spectrophotomet?ric Detector HPLC UV
Shimadzu GC Autoinjector&Vi?al Carousel AOC 20i,20s EUC
|
在線咨詢 
在線客服：0571-87774297
