PLC是以微处理器为基础，综合了计算机技术、自动控制技术和通信技术，用面向控制过程面向用户的“自然语言”编程，适应工业环境，简单易懂、操作方便、可靠性高的新一代通用工业控制装置。PLC是在继电器顺序控制基础上发展起来的以微处理器为核心的通用自动控制装置。

可编程序控制器是一种数字运算操作电子系统，专为在工业环境下应用而设计。它采用了可编程序的存储器，用来在其内部存储执行逻辑运算、顺序控制、定时、计数和算术运算等操作指令，并通过数字的、模拟的输入和输出，控制各种类型的机械或生产过程。可编程序控制器及其有关的外围设备，都应按易于与工业控制系统形成一个整体、易于扩充其功能的原则设计。

PLC产品种类繁多，其规格和性能也各不相同。对于PLC，通常根据其结构形式的不同、功能的差异和I/O点数的多少等进行大致分类。

按结构形式分类

根据PLC的结构形式，可将PLC分为整体式和模块式两类。

整体式PLC

整体式PLC是将电源、CPU、I/O接口等部件都集中装在一个机箱内，如图所示。具有结构紧凑、体积小、价格低的特点。小型PLC一般采用这种整体式结构。整体式PLC由不同I/O点数的基本单元（又称主机）和扩展单元组成，基本单元内有CPU、I/O接口、与I/O扩展单元相连的扩展口以及与编程器或EPROM写入器相连的接口等；扩展单元内只有I/O和电源等，而没有CPU。基本单元和扩展单元之间一般用扁平电缆连接。整体式PLC一般还可配备特殊功能单元，如模拟量单元、位置控制单元等，使其功能得以扩展。

2）模块式PLC

模块式PLC将PLC的各组成部分分别做成若干个单独的模块，如CPU模块、I/O模块、电源模块（有的含在CPU模块中）以及各种功能模块。模块式PLC由框架或基板和各种模块组成，模块装在框架或基板的插座上，如图所示。这种模块式PLC的特点是配置灵活，可根据需要选配不同规模的系统，而且装配方便，便于扩展和维修。大、中型PLC一般采用模块式结构。

还有一些PLC将整体式和模块式的特点结合起来，构成所谓的叠装式PLC。叠装式PLC的CPU、电源、I/O接口等也是各自独立的模块，但它们之间是靠电缆进行连接的，并且各模块可以一层层地叠装。这样，不但系统可以灵活配置，还可做得体积小巧。

2.2.按功能分类

根据PLC的功能不同，可将PLC分为低档、中档、。

WITTENSTEIN GEARBOX ALPHA V-DRV 063 40:1, VDH063-MF1-40-041-OG1MPLB4530K
Wittenstein Alpha VDS 050-MF1-7 -931-0F Servo Worm Gearhead Ratio 7
Wittenstein Alpha TP-050S-MF1-10 Planetary Gear Reducer 10:1 Ratio TP050SMF110
Wittenstein Alpha SPK-075-MF2-5-131-000 Gear Box SPK075MF25131000 1326AB-B430
WITTENSTEIN ALPHA SP-100S-MF2-16-0E1-2S 16:1 PLANETARY GEAR REDUCER B422173
Wittenstein Alpha SP-075S-MF1-7-OE1-2S Multi-Stage Gearhead Ratio i=7
WITTENSTEIN ALPHA SP075S-MC2-16 -1C1-2K-PS1
Wittenstein Alpha SP-075-MF1-2-131-000 Right Angle GearHead SP075MF12131000 
Wittenstein Alpha SP-060S-MF1-10-0C1-2S Gear Reducer 10:1 SP060SMF1100C12S 
WITTENSTEIN ALPHA SP 140S-MC1-5-1K1-2K-PS1
WITTENSTEIN ALPHA SP 140S-MC1-3 -1K1-2K PS1
WITTENSTEIN ALPHA SP 100X-MC1-7-0G1-2K-KF 7:1 GEAR REDUCER D287303
WITTENSTEIN ALPHA SP 100S-MF2-28-1E1-2S 24MM 32MM 28:1 GEARHEAD REDUCER B464293
WITTENSTEIN ALPHA SP 100S-MC1-3 - 0K0-2K Getriebe Planetengetriebe NEU
Wittenstein Alpha SP 075S-MF1-3-1E1-2S Gearhead 3:1 Ratio 103mm Frame Size
Wittenstein Alpha SP 060S-MF1-5-1B1-2S Gearhead 5:1 Ratio 70mm Frame Size
Wittenstein Alpha SP 060S-MF1-3-1C1-2S Gearhead 3:1 Ratio 70mm Frame
Wittenstein Alpha SP 060S-MF1-3-1B1-2S Gearhead 3:1 Ratio 70mm Frame Size
Wittenstein Alpha SP 060S-MF1-10-181-125 Gearhead 10:1 Ratio 70mm Frame
Wittenstein Alpha SK+100S-MF2-50 Right Angle Gear Head Reducer
WITTENSTEIN ALPHA SK+ 140S-MF1-7 -1K1-P&G
Wittenstein Alpha SK+ 100S-MF1-5 -2H1-1K Getriebe Winkelgetriebe Umlenkgetriebe
Wittenstein Alpha Right-Angle Gear Reducer, 40:1 Ratio
WITTENSTEIN ALPHA RIGHT ANGLE 42 PLANETARY GEAR REDUCER TPK 025-MF3-42-031-000
WITTENSTEIN ALPHA RATIO 7 PLANETARY GEARHEAD SP 140-MF1-7 -421-000
WITTENSTEIN ALPHA RATIO 5 PLANETARY GEARHEAD SP 140-MF1-5 -421-000
Wittenstein Alpha Planetengetriebe TP 010-MF2-91-031-000 -  -
Wittenstein alpha Planetengetriebe SP075S-MC2-70-0C1-2K Getriebe #7484
Wittenstein alpha Planetengetriebe SP 060S-MF2-16-0B1-2S Getriebe #7830
Wittenstein Alpha LPK070-M03-25 Servo Planetary Gearhead 25:1 Ratio - 
Wittenstein Alpha LPK 090-M02-3-111 Right-Angled Gearhead 3:1 Ratio
Wittenstein Alpha LPK 070-M03-25-111 Right Angle Gear Reducer 25:1 Ratio
Wittenstein Alpha LP-050S-MF1-10-1B1-3S Gearhead LP050SMF1101B13S 
WITTENSTEIN alpha LP 155-MO2-50-111-000
Wittenstein Alpha LP 120-M02-16-111-000 Servo Gear Head Reducer
WITTENSTEIN ALPHA LP 090-M01-3-111-001 GEAR REDUCER, 
WITTENSTEIN ALPHA LP 070-M02-15-111-000  GEAR HEAD LP070M0215111000
Wittenstein Alpha LP 070-M01-7-111-000 Gearhead 7:1 Ratio 70mm Frame Size
WITTENSTEIN ALPHA LP 070-M01-10-111-000 10:1 GEAR REDUCER POWER TRANSMISSION
Wittenstein Alpha HG+ 100S-MF1-10-6H1-1K00 Right Angle Planetary Gear Reducer
Wittenstein Alpha Gmbh LP070-M01-7-111-000 Gearhead LP070M017111000 
Wittenstein Alpha Getriebe TP 050S-MF2-16 OK1-25 --
Wittenstein alpha getriebe SP 140S-MF1-10 -011-25
Wittenstein Alpha Getriebe Kegelradgetriebe SK 060S-MF2-20-1B1-1S10 mit Motor
Wittenstein ALPHA Getriebe alpheno 040-1 i=4 --
WITTENSTEIN alpha Getribe SK.140S-MF 1-3 - 1K1
WITTENSTEIN ALPHA GEARHEAD SP 140S-MF1-7 NNB
WITTENSTEIN ALPHA GEARBOX SP 140S-MF2-16 -1K0-2S
WITTENSTEIN ALPHA GEARBOX SK-1405-MF1-4-0K-1K00 **
Wittenstein Alpha Gearbox
Wittenstein Alpha Gearbox
Wittenstein Alpha Gear Head with shaft. LP 050S-MF1-10-1B1-3S (4 units)
Wittenstein Alpha Gear Box Reducer LPK-090-M02-3-111 Ratio 3:1 Right Angle
WITTENSTEIN ALPHA 7:1 RATIO PLANETARY GEAR REDUCER SP 140S-MF1-7-0K1-2S
Wittenstein alpha 1000mm Mod 2 performance class rack
WITTENSTEIN ALPHA 10:1 RATIO PLANETARY GEAR REDUCER SP 060S-MF1-10-0B1-2S
WITTENSTEIN ALPHA 090-MO1-10-111-000 RATIO:10 10000967 GEAR REDUCER
Wittenstein Alpha -- SP 060S-MF1-5-1B1-2S -- High Speed Gear Reducer ()
Wittenstein Alpha -- SP 060S-MF1-5-1B1-2S -- High Speed Gear Reducer ()
WITTENSTEIN alpha - Planetengetriebe SP MF-Version i=4 - SP 140S-MF1-4 -4K1-2S
Wittenstein / alpha Planetengetriebe SP075S-MF1-5-1G0-2S OVP
Wittenstein / alpha Planetengetriebe SP 075S-MF1-10-0E0-2S OVP
Wittenstein / alpha Planetengetriebe SP 075S-MF1-10-0E0-2S NOV
Wittenstein / alpha Planetengetriebe SP 075S-MF1-10-0E0-2S GEB
Wittenstein / alpha Getriebe HG+ 075S-MF2-20-6C1-1S10 20034772 OVP
WIREMASTER FIT-221-1/8 TUBING, HEATSHRINK,IN=RL, 45 FT ALPHA WIRE
WIRE, YEL, 32AWG, 7/40AWG, 30.5M MPN: 2840/7 YL005 ALPHA WIRE
WIRE, YEL, 28AWG, 7/36AWG, 30.5M MPN: 3048 YL005 ALPHA WIRE
WIRE, YEL, 28AWG, 19/40AWG, 30.5M MPN: 2842/19 YL005 ALPHA WIRE
WIRE, YEL, 26AWG, 7/34AWG, 30.5M MPN: 5853 YL005 ALPHA WIRE
WIRE, YEL, 24AWG, 7/32AWG, 30.5M MPN: 3050 YL005 ALPHA WIRE
WIRE, YEL, 22AWG, 7/30AWG, 30.5M MPN: 3251 YL005 ALPHA WIRE
WIRE, YEL, 22AWG, 19/34AWG, 30.5M MPN: 5855 YL005 ALPHA WIRE
WIRE, YEL, 20AWG, 10/30AWG, 30.5M MPN: 3053 YL005 ALPHA WIRE
WIRE, YEL, 18AWG, 16/30AWG, 30.5M MPN: 1555 YL005 ALPHA WIRE
WIRE, YEL, 16AWG, 19/29AWG, 30.5M MPN: 5858 YL005 ALPHA WIRE
WIRE, WHT, 32AWG, 7/40AWG, 30.5M MPN: 2840/7 WH005 ALPHA WIRE
WIRE, WHT, 30AWG, 7/38AWG, 30.5M MPN: 1851 WH005 ALPHA WIRE
WIRE, WHT, 28AWG, 7/36AWG, 30.5M MPN: 3048 WH005 ALPHA WIRE
WIRE, WHT, 28AWG, 7/36AWG, 30.5M MPN: 2842/7 WH005 ALPHA WIRE
WIRE, WHT, 28AWG, 7/36AWG, 30.5M MPN: 1852 WH005 ALPHA WIRE
WIRE, WHT, 28AWG, 19/40AWG, 30.5M MPN: 2842/19 WH005 ALPHA WIRE
WIRE, WHT, 26AWG, 7/34AWG, 30.5M MPN: 1853 WH005 ALPHA WIRE
WIRE, WHT, 26AWG, 19/38AWG, 30.5M MPN: 2843/19 WH005 ALPHA WIRE
WIRE, WHT, 24AWG, 7/32AWG, 30.5M MPN: 1550 WH005 ALPHA WIRE
WIRE, WHT, 22AWG, 7/30AWG, 30.5M MPN: 5855/7 WH005 ALPHA WIRE
WIRE, WHT, 22AWG, 1/22AWG, 30.5M MPN: 1561 WH005 ALPHA WIRE
WIRE, WHT, 20AWG, 10/30AWG, 30.5M MPN: 3053 WH005 ALPHA WIRE
WIRE, WHT, 20AWG, 1/20AWG, 30.5M MPN: 2856/1 WH005 ALPHA WIRE
WIRE, WHT, 18AWG, 16/30AWG, 30.5M MPN: 3055 WH005 ALPHA WIRE
WIRE, WHT, 12AWG, 19/25AWG, 30.5M MPN: 5859/12 WH005 ALPHA WIRE
WIRE, WHT, 10AWG, 105/30AWG, 30.5M MPN: 3081 WH005 ALPHA WIRE
WIRE, VLT, 28AWG, 7/36AWG, 30.5M MPN: 2842/7 VI005 ALPHA WIRE
WIRE, VLT, 20AWG, 10/30AWG, 30.5M MPN: 3053 VI005 ALPHA WIRE
WIRE, UL1429, 26AWG, BLUE, 304.8M MPN: 7053 BL001 ALPHA WIRE
WIRE, UL1213, 30AWG, ORANGE, 30.5M MPN: 5851 OR005 ALPHA WIRE
WIRE, UL1213, 26AWG, WHITE, 304.8M MPN: 5853 WH001 ALPHA WIRE
WIRE, UL1213, 24AWG, WHITE, 304.8M MPN: 5854/7 WH001 ALPHA WIRE
WIRE, UL1213, 20AWG, RED, 304.8M MPN: 5856 RD001 ALPHA WIRE
WIRE, UL1061, 24AWG, YELLOW, 305M MPN: 3250 YL001 ALPHA WIRE
WIRE, UL1061, 20AWG, BLACK, 305M MPN: 3252 BK001 ALPHA WIRE
WIRE, UL1015, 24AWG, ORANGE, 305M MPN: 3070 OR001 ALPHA WIRE
WIRE, UL1015, 24AWG, BLACK, 305M MPN: 3070 BK001 ALPHA WIRE
WIRE, UL1015, 22AWG, YELLOW, 305M MPN: 3071 YL001 ALPHA WIRE
WIRE, UL1015, 20AWG, RED, 305M MPN: 3073 RD001 ALPHA WIRE
WIRE, UL1015, 20AWG, BROWN, 305M MPN: 3073 BR001 ALPHA WIRE
WIRE, UL1015, 18AWG, BLACK, 305M MPN: 3075 BK001 ALPHA WIRE
WIRE, UL1015, 16AWG, GRN/YEL, 305M MPN: 3077 GY001 ALPHA WIRE
WIRE, UL1007, 28AWG, GREEN, 305M MPN: 3048 GR001 ALPHA WIRE
WIRE, UL1007, 20AWG, GREY, 305M MPN: 3053 SL001 ALPHA WIRE
WIRE, UL1007, 20AWG, BROWN, 305M MPN: 3053 BR001 ALPHA WIRE