西门子的S7-200的程序结构

  过程映像输入/输出（I/Q）、变量存储器V、内部存储器位M、定时器T、计数器C等属于全局变量。S7-200的程序组织单元(ProgramOrganizationalUnit，简称为POU)包括主程序、子程序和中断程序。每个POU均有自己的64字节局部变量，局部变量只能在它所在的POU中使用。与此相反，全局变量可以在各POU中使用。

  下面是子程序可以使用的局部变量：

  1)TEMP(临时变量)是暂时保存在局部数据区中的变量。只有在执行该POU时，定义的临时变量才被使用，POU执行完后，不再保存临时变量的数值。

  2)IN是由调用它的POU提供的输入参数。

  3)OUT是返回给调用它的POU的输出参数(子程序的执行结果)。

  4)IN_OUT是输入_输出参数，其初始值由调用它的POU传送给子程序，并用同一变量将子程序的执行结果返回给调用它的POU。

  主程序和中断程序的局部变量中只有临时变量TEMP。

  具有输入、输出参数和局部变量的子程序易于实现结构化编程，对于长期生产同类设备或生产线的厂家尤为有用。这些厂家的编程人员为设备的各组件或工艺功能编写了大量的通用的子程序。即使不知道子程序的内部代码，只要知道子程序的功能和输入、输出参数的意义，就可以通过程序之间的调用快速“组装”出满足不同用户要求的控制程序。就好像用数字集成电路芯片组成复杂的数字电路一样。

  子程序如果没有输入、输出参数，它和调用它的程序之间没有清晰的接口，很难实现结构化编程。

  子程序如果没有局部变量，它和调用它的程序之间只能通过全局变量来交换数据，子程序内部也只能使用全局变量。将子程序和中断程序移植到别的项目时，需要重新统一安排它们使用的全局变量，以保证不会出现地址冲突。当程序很复杂，子程序和中断程序很多时，这种重新分配地址的工作量非常大。

  如果子程序和中断程序有局部变量，并且它们内部只使用局部变量，不使用全局变量，因为与其他POU没有地址冲突，不需作任何改动，就可以将子程序移植到别的项目中去。

 NIB VEXTA C8384-9212H C83849212H STEPPING MOTOR 2 PHASE 1.8* / STEP 4.4A 2.5V
1 PC  VEXTA RKD514L-C servo drive Tested
1 PC Used AXHD15K VEXTA stepper driver
1 PC Used AXHD30K VEXTA stepper driver
1 PC Used VEXTA Dongfang Motor Vibration Damper D6CL-6.3F
1 PC Used Vexta Oriental Motor UDK5107N In Good Condition
1 PC Used Vexta PCB AXHD100K In Good Condition
1 PC Used Vexta UDK5114N In Good Condition
1 PC VEXTA RKD514L-C servo drive Tested
1 PC VEXTA Servo Drive RKD514L-A Tested
1 PC VEXTA Stepper Motor Driver RC-204A Tested
1 PCS   VEXTA stepper driver   CSD5814N   tested
1 PCS   VEXTA stepper driver  CSD2112-P   tested
1 PCS   VEXTA stepper driver  CSD2120-P   tested
1 PCS   VEXTA stepper driver  CSD2120P2   tested
1 PCS   VEXTA stepper driver  CSD5814N-P   tested
1 PCS   VEXTA stepper driver CMD2112P   tested
1 PCS   VEXTA stepper driver CSD5807N    tested
1 PCS   VEXTA stepper driver CSD5807N-P  tested
1 pcs  VEXTA   Motor SD5107P2  tested
1 pcs  VEXTA  Motor PK243A1-SG10  tested
1 pcs  VEXTA drive SD5107 board  Tested
1 PCS NEW IN BOX VEXTA Oriental Governor TMP-1
1 pcs used Dongfang VEXTA stepping motor driver 2-PHR5E DRIVER UD2115B
1 pcs VEXTA 2.8A CSD2120-P   stepper motor driver tested
1 pcs VEXTA 2.8A CSD2120-P stepper motor driver tested
1 pcs VEXTA CSD5807N-P 0.75A   stepper motor driver tested
1 pcs VEXTA CSD5807N-P 0.75A stepper motor driver tested
1 pcs VEXTA CSD5814N-P    stepper motor driver tested
1 pcs VEXTA CSD5814N-P stepper motor driver tested
1 pcs VEXTA drive SD5107 board Tested
1 PCS VEXTA five-phase stepper driver DFC5103P in good condition
1 PCS VEXTA five-phase stepper driver UDX5107N 0.75A 100V in good condition
1 pcs VEXTA Motor PK243A1-SG10 tested
1 pcs VEXTA Motor SD5107P2 tested
1 PCS VEXTA Oriental BLHD15K DC24V Brushless DC Motor Driver in good condition
1 PCS VEXTA Oriental driver AXHD15K in good condition
1 PCS VEXTA stepper driver CMD2112P tested
1 PCS VEXTA stepper driver CSD2109-P in good condition
1 PCS VEXTA stepper driver CSD2112-P tested
1 PCS VEXTA stepper driver CSD2120-P tested
1 PCS VEXTA stepper driver CSD2120P2 tested
1 PCS VEXTA stepper driver CSD5807N tested
1 PCS VEXTA stepper driver CSD5807N-P tested
1 PCS VEXTA stepper driver CSD5814N tested
1 PCS VEXTA stepper driver CSD5814N-P tested
1 product rating- C173376 Lot 4 Vexta PK266-01B 2-Phase 1.8°/Step Stepping Motor (DC1A, 7.4Ω)
1 product rating- GATES 3VX400 SUPER HC VEXTA POWERBAND BELT
1 product rating- ONE USED VEXTA PH265M-31
1 product rating- ONE Vexta 2-Phase Stepping Motor Model PK264-02A
1 product rating- Oriental Motor ASD18A-K Vexta AlphaStep Closed Loop Motor Driver
1 product rating- Oriental Motor ASD18A-K Vexta AlphaStep series Closed Loop Motor Driver
1 product rating- ORIENTAL MOTOR PH265M-31 / PH265M31 (USED TESTED CLEANED)
1 product rating- Oriental Motor PK264-02A Vexta Stepping Motor 2-Phase 2Amp 1.4Ω PK26402A
1 product rating- ORIENTAL MOTOR PK545-NB / PK545NB (USED TESTED CLEANED)
1 product rating- ORIENTAL MOTOR UDX5114N / UDX5114N (REPAIR EVALUATION ONLY)
1 product rating- ORIENTAL MOTOR VEXTA PK266-01B STEPPING MOTOR UNIPOLAR 2 PHASE
1 product rating- ORIENTAL VEXTA STEPPING MOTOR UNIT PK264-02A 2- PHASE DC 2A 1.8/STEP
1 product rating- Vexta (Oriental Motor Co.), Model PK266-01B, Stepping Motor, DC 1A, 7.4 Ohm
1 product rating- Vexta 2 Phase Stepping Motor - PH265M-31
1 product rating- Vexta 2 Phase Stepping Motor 1/8" Step PK266-01B
1 product rating- VEXTA 2phase Oriental stepper drive CSD2109-P
1 product rating- Vexta PH265M-31 2-Phase Stepping Motor, DC6V, 0.85A/Phase
1 product rating- VEXTA PH265M-31 Stepping Motor, 2 Phase 0.9 degrees Per Step 6 Volt DC
1 product rating- Vexta PK244PA 2-Phase Stepping Motor DC 1.2A
1 product rating- VEXTA PK266-01B Stepping Motor 2-Phase 1.8o/Step 1ADC 7.4Ohm PK266-01B *NEW*
1 product rating- Vexta Stepping Motor PK266-01B w/USDigital E3-2500-250-I-D-D-B Encoder
1 x Vexta PH266-02 2 Phase Stepping Stepper Motor 1.8 deg/step DC 6v  1.2 AMP
1 x Vexta PH266-02 2 Phase Stepping Stepper Motor 1.8 deg/step DC 6v 1.2 AMP
1.0 out of 5 stars.
182698 New-No Box, Oriental K0177-M Vexta Brushless DC Motor 60W, 2000r/min
193316 New-No Box, Vexta A5246-9412K Stepper Motor, 2 Phase, 2.1A
1Pair New VEXTA EIC4081 EIC4091 ZIP-15  #F4594 CY
1Pair New VEXTA EIC4081 EIC4091 ZIP-15 #F4594 CY
1Pair New VEXTA EIC4081 EIC4091 ZIP-15 #F4594 CY 
1PC   used Vexta 2-Phase Driver UDK2120 Tested
1PC  USED VEXTA MSP101 Driver
1pc  Used VEXTA MSP101 Driver Tested
1PC  Used VEXTA Oriental motor speed regulator SG8030J
1PC  Used VEXTA Oriental motor stepping PK566-NB
1PC NEW VEXTA  SBR11-ZP
1PC NEW vexta  SS22M-SSSD
1pc NEW VEXTA governor DSP501M
1PC NEW VEXTA SBR11-ZP
1PC NEW vexta SS22M-SSSD
1pc Omron Proximity Switch TL-N5ME2 10-30VDC 2M
1pc USED    VEXTA drives MSP101        #TT2
1pc used  VEXTA  CSD2112-P
1PC USED  VEXTA 2phase Oriental stepper drive CSD2109-P
1PC USED Eastern VEXTA drive CSD2112-P
1pc USED FOR VEXTA STEP MOTOR PK545-NBC-C25 ,Without wire #T86m YS
1PC Used Good VEXTA ASD13C-A #T94R YS yh
1PC Used Japan Eastern VEXTA 28 Series 1.8 degree 0.95A Double Out Axis #w2916wx
1pc USED Oriental Motor Super Vexta UDX5107N 5-Phase Stepping Motor Amplifier
1PC Used Oriental VEXTA five phase stepper drivers plate PMD03C tested
1pc USED Super Vexta 5-Phase Motor Driver Model UDX5107 Tested Good
1pc USED Super VEXTA UDX5114 5-PHASE Servo Driver Tested
1pc USED Super VEXTA UDX5114 5-PHASE Servo Driver Tested
1PC used Vexta 2-Phase Driver UDK2120 Tested
1PC USED VEXTA 2phase Oriental stepper drive CSD2109-P
1PC Used Vexta 2-Phase Stepping Motor Model PK264-02A Tested
1pc USED Vexta 5 phase Stepping Driver Motor DFC1507 Tested with Warranty
1PC USED VEXTA AXHD30K 24VDC Motor Driver Tested Good
1Pc Used Vexta AXUD40C ms
1PC Used VEXTA AXUD40C tested
1pc used VEXTA C7325-9012
1PC USED VEXTA CSD2109-P Oriental 2-phase Stepper Driver Tested Good 24-36V 1.4A
1pc used VEXTA CSD2112-P
1PC USED VEXTA CSD2120-P Oriental Stepper Motor Driver (CSD2120P) 2.8A Good
1PC Used VEXTA CSD5814N-P Oriental Stepper Driver (CSD5814NP)
1pc used VEXTA drive AXHD30K
1pc used VEXTA drive CSD5714B
1PC Used VEXTA drive MSP-1W
1PC Used VEXTA Driver ASD18B-K
1pc USED VEXTA drives MSP101 #TT2
1pc USED VEXTA drives MSP-2W
1pc USED VEXTA drives MSP-2W
1PC used Vexta Electric machinery 0GN60K
1PC used Vexta Electric machinery 0GN60K
1PC USED VEXTA MC-S0514-L
1PC USED VEXTA MC-S0514-L
1PC Used VEXTA Motor PK243-01B tested
1PC used VEXTA Motor PK566-NB  #fi
1PC used VEXTA Motor PK566-NB #fi
1PC USED VEXTA MSP101 Driver
1PC used VEXTA MSP101 Driver Tested
1PC used VEXTA MSP101 Driver Tested Free Shipping
1PC used Vexta MSP301N Speed Controller
1PC used Vexta MSP301N Speed Controller
1PC Used VEXTA Oriental drive CSD2112-P
1PC Used Vexta Oriental Motor 5 Phase Driver CSD5814N-P
1PC USED Vexta Oriental Motor CSD5814N-P  Drive card
1PC USED Vexta Oriental Motor CSD5814N-P Drive card
1PC used VEXTA Oriental Motor Drives ASD13C-A Tested
1PC used VEXTA Oriental Motor Drives ASD13C-A Tested
1PC Used Vexta Oriental Motor PK564AN-TG10 Stepping Motor Tested
1PC Used VEXTA Oriental motor speed regulator SG8030J
1PC Used VEXTA Oriental motor stepping PK566-NB
1PC USED Vexta Oriental Motor UDK5107N
1PC USED Vexta Oriental Motor UDK5107N
1PC USED VEXTA ORIENTAL SG8030J
1PC used VEXTA ORIENTAL SG8030J #fl
1PC USED VEXTA Oriental stepper drives MSP-2W
1PC Used Vexta Oriental Stepping Motor PK566-NA
1PC USED VEXTA PH265M-31
1PC Used VEXTA PH265M-31 tested
1PC Used VEXTA PK266-03A
1PC USED VEXTA PK545-NA-C21 5-phase Stepping Motor Tested
1PC USED VEXTA PK566AW Stepping Motor #T85M YS
1PC Used VEXTA Servo Driver RKD514L-C
1PC USED VEXTA SG8030J 24V #P2389 YL
1PC USED VEXTA stepper driver CMD2109P board type
1PC Used VEXTA Stepper Driver DFC5107P Tested Good Condition
1PC Used VEXTA Stepper Driver DFC5107P Tested Good Condition
1PC used VEXTA Stepper Driver PMD07U
1PC USED VEXTA Stepping driver CSD2112-P
1PC USED VEXTA Stepping driver CSD2112-P fast ship#XR
1PC USED VEXTA stepping driver PMD07U
1PC Used VEXTA Stepping motor motor PK266-03A
1Pc Used Vexta TMP-1 ic
1pc used VEXTA UDK5107N   #TT2
1pc used VEXTA UDK5107N #TT2
1PC used VEXTA UDX5114   #1
1PC used VEXTA UDX5114 #1
1pc VEXTA  5 phase stepper driver UDX5107N supporting PH569-A 10 lines  #F334 CY
1Pc Vexta 2IJ3GB-A Used nc
1PC VEXTA 2phase Oriental stepper drive CSD