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。

Allen Bradley SLC500-10 Slot Rack w/Proc 1747-L542/C &

Norgren Smart Pumps / Vacuum System - VMS 2110 24 V

Fanuc AC Servo Motor A06B-0127-B175

Allen-Bradley 1794-OB16P Flex I/O Output Module

Olsun 45 KVA 480 HV / Dry type Class AA Transformer
415Y/240-120 LV / 3 Phase

Goodyear FHP 4L280 Power Transmission Belt

Fanuc AC Servo Motor A06B-0153-B675

PILZ Pnoz 11 Safety Relay - Emergency Stop Relay

FANUC A16B-1212-0871/?12C POWER SUPPLY

Allen Bradley 1785-L40B/D Controller w/NP5 Kit

Allen-Bradley 1794-ADN Flex I/O DeviceNet Adapter

Allen Bradley AB 104-B110NZ243 Series A Contactor
Reversing Starter

ALLEN BRADLEY 500-DOD920 New In Box / 115-120 V

Honeywell Temperature Controller L456A 1008 NIB
2-Wire 250V Max - 5 Ft copper capiliary 

NIB Honeywell Serviceline Pneumatic Thermostat 
TP970A 2038 4 (Direct acting, range 60-90F)

Allen-Bradley 1794-IB10x086 Flex I/O Combo Module

Allen-Bradley 1794-IB16 Flex I/O Input Module w/TB3Base

Reliance Electric Variable Speed Drive - 125 HP 
pulled from operating Machining center

Fanuc A16B-2201-0891/?03A Ethernet Remote PCB 

Fanuc A05B-2316-C105 3 Slot Back Plane

Fanuc AC Servo Motor A06B-0356-B756

Fanuc Robotics - Brake Release Unit / 6 axis capability

FANUC A16B-3200-0040/?04C MAIN CPU PCB MODULE

FANUC A16B-1212-0931/?03B EMERGENCY STOP CONTROL
BOARD

B74 GATES HI-POWER II VBELT

GATES Part # 3740 Truflex Belt 21/32"x 74" 17x1880mm

FANUC Servo Amplifier Unit A06B-6089-H105

GATES Part # 3740 {Truflex Belt 5L 21/32" x 74"}

CONTROL TECHNIQUES 9500-8603 QUANTUM III DC DRIVE 
15-30 HP

Moog Brushless Sevro Motor / Model 306-131A - NEW

Allen Bradley PowerFlex 70 AC Drive2HP 20AD3P4A3AYNNNN?N

NIB Honeywell Heavy duty Heating/Cooling Thermostat
T6051A 1016

Square D Reversing Starter 8702 Type SDO-2 -New In Box

Square D 1S1FIS 1 KVA General Purpose Transformer Used

Allen Bradley AB 104-A75NZ243 Series A Contactor
Reversing Starter

Honeywell Ultraviolet Flame Amplifier - 7800 Series NIB
R7849 A 1023 - Solid State plug in amplifier

Allen Bradley AB 104-B180ND3 Series A Contactor
Reversing Starter

NIB Honeywell Sailswitch - 43A 1003 1 (2wire / 250Vmax)

Allen Bradley 1747-L511/B SLC 5/01 CPU 1747L511 / B

Allen Bradley 1756-DHRIO/B Logix DH+/RIO Communication

Allen Bradley 1747-L541/B SLC 500 5/04 1747L541

Allen Bradley 1747-L542/B SLC 5/04 CPU 1747L542 / B

Reliance 0-51874 Module Static Seq SCCA

Reliance 0-48652 PC Board Meter Calibration

Reliance 0-48652-25 PC Board

Reliance 0-48654 PC Board- AC Tach Rectifier

Reliance 0-49017-83 Card Pack

Reliance 0-51375 PC Board

Reliance 0-51418-4 PC Board

Reliance 0-51419 PC Board Gate Coupling

Reliance 0-51421-3 RC Network

Reliance 0-51425-1 Rectifier - AC Tach

Reliance 0-51426 PC Board- Field Loss

Reliance 0-51444 Driver Board

Reliance 0-51445 Controller Board

Reliance 0-51446 PC Board

Reliance 0-51447-3A PC Board - PC Network- 460V

Reliance 0-51486-24 PC Board

Reliance 0-51486-39 PC Board

Reliance 0-51486-56 PC Board ETR - 14 Pin

Reliance 0-51811-1 Tester Card- Voltmeter- TSTB

Reliance 0-51829-2 PC Board Linear Voltage- LVTC

Reliance 0-51831 PC Board Current Voltage CVTB

Reliance 0-51831-1 PC Board Current Voltage CVTB

Reliance 0-51831-3 PC Board Current Voltage CVTD

Reliance 0-51839-4 PC Board Relay Card IRCE

Reliance 0-51845-1 PC Board Power Supply PRSB

Reliance 0-51846-25A PC Board

Reliance 0-51847 Voltage Detector Board VLDB

Reliance 0-51848-1 PC Board

Reliance 0-51849 PC Board Gate Driver GBCA

Reliance 0-51851-5 PC Board Control Regulator

Reliance 0-51851-6 PC Board Control Regulator- CRCG

Reliance 0-51862-1 PC Board Universal Sum AMP

Reliance 0-51865 (CLDA) PC Board- Current Loop Drive

Reliance 0-51865-1 (CLDB) PC Board- Current Loop Drive

Reliance 0-51865-9 Module Current Loop DRV-CLDK

Reliance 0-51874-2 PC Board Static Sequence SSCC

Reliance 0-51881-1 Circuit Card Ext Term CNTR- ETCB

Reliance 0-51884 LSCA Moldule LOG SIG COND

Reliance 0-51890-6 PC Board DPSG

Reliance 0-51893-2 Field Controller - FCCC

Reliance 0-51893-3 PC Board- Field Exciter FCCD

Reliance 0-51899-2 Control Module Extender Card

Reliance 0-51901-A Armature Reg.

Reliance 0-51902 Driver Card

Reliance 0-51902-5 PC Board

Reliance 0-51903-A Power Supply

Reliance 0-52012 PC Board Gate Driver MaxPak

Reliance 0-52014 PC Board Timed Voltage Reference

Reliance 0-52824 Current Loop Regulator

Reliance 0-54349-2 PC Board Phase