PLC基本组成包括中央处理器(CPU)、存储器、输入/输出接口(缩写为I/O，包括输入接口、输出接口、外部设备接口、扩展接口等)、外部设备编程器及电源模块组成，见图1。PLC内部各组成单元之间通过电源总线、控制总线、地址总线和数据总线连接，外部则根据实际控制对象配置相应设备与控制装置构成PLC控制系统。
Vickers Vane Pump 35V25A 1A22R #55825
Mould Tek Circuit Board CAC-AGRFDR-2-A-9/95 #14793
(8061) Allen Bradley Input Module 1771-IQB
(L4) 1 SQUARE D CIRCUIT BREAKER Q
Red Lion Controls APLCK, 11 to 14 VDC, Real Time Clock / Elapsed Time Indicator
Armstrong H-1252 3/4" Drive, 1 5/8", 12 Point Hi Tension Socket
Brunson 381 Series Alignment Telescope; No Eyepiece, includes Case
(5241) United Electric Pressure Switch 3-30 Psid 316SS 1/2" J400KS147B
Hcx8316G014Mo15380 ValveHcx8316G44V15380 Solenoid Valve
Parker 71315SN2ENJ1N0C111P3 Valve Skinner T66674
Barber Colman SPC/Network Module 80SAV-00 #15922
RELIANCE **
Siemens Slot Rack 6ES5 155-3UA11 Scratch & Dent #48324
(U2) 1 CROUSE-HINDS AFUL-1 MINE SIGNAL SWITCH
Hytrol Roller Gate Conveyor Conveyor137 #56137
Uson, Calibrated Leak Rate 3 ssc-min @ 3 Psig, Includes Case
(6245) Vickers Pressure Reducing Valve DGMX2-3-PP-CW-B-40
(RR7-1) 1 NIB TELEMECANIQUE XU2P18PP340DLR PHOTOELECTRIC SENSOR
(9792) Cutler Hammer Photoelectric Head E51DP3
Barber Colman Sequence Hydraulic PC Board A #19679
(7119) Vaccon Variable Vacuum Pump 1/4" Id Vdf150 Nip
Bulldog Electric Products Switch Plug Switch Plug118 #56118
ARRA WG119P1 (WR-119) 7.05 to 10.0 GHz, Offset Core, Waveguide Load-Termination
(X5-22) 1 PANALARM B MODULE CALIBRATOR
Fanuc Pulse Encoder AV531 #71630
Sanyo Denki Servo Amplifier 65AA030PXR13 #11193
Allen Bradley Versa View 200R 6155R-NP2KH Ser A #80149
Weinschel 9426, DC to 1.0 GHz, 0 to 15 dB, 1W, SMA, 50 ohm, Variable Attenuator
Whitey Ball Valve SS-67TSW24P #64771