在運用者看來，不必要詳細剖析CPU的內部電路，但對各有些的作業機制仍是應有足夠的了解。CPU的操控器操控CPU作業，由它讀取指令、解說指令及履行指令。但作業節奏由震動信號操控。運算器用于進行數字或邏輯運算，在操控器指揮下作業。寄存器參加運算，并存儲運算的中心成果，它也是在操控器指揮下作業。
CPU速度和內存容量是PLC的首要參數，它們決議著PLC的作業速度，IO數量及軟件容量等，因而約束著操控規模。
I/O模塊
PLC與電氣回路的接口，是經過輸入輸出有些（I/O）完結的。I/O模塊集成了PLC的I/O電路，其輸入暫存器反映輸入信號狀況，輸出點反映輸出鎖存器狀況。輸入模塊將電信號改換成數字信號進入PLC體系，輸出模塊相反。I/O分為開關量輸入（DI），開關量輸出（DO），模擬量輸入（AI），模擬量輸出（AO）等模塊。
常用的I/O分類如下：
開關量：按電壓水平分，有220VAC、110VAC、24VDC，按阻隔方法分，有繼電器阻隔和晶體管阻隔。
模擬量：按信號類型分，有電流型（4-20mA,0-20mA）、電壓型（0-10V,0-5V,-10-10V）等，按精度分，有12bit,14bit,16bit等。
除了上述通用IO外，還有特別IO模塊，如熱電阻、熱電偶、脈沖等模塊。
按I/O點數確定模塊標準及數量，I/O模塊可多可少，但其最大數受CPU所能辦理的根本裝備的才能，即受最大的底板或機架槽數約束。
電源模塊
ABB 900060 DDR Switch cable
ABB 3HAB2136-1 Teach pendant S3
ABB 3HAB2151-1 Teach pendant S3
ABB 3HAB2477-1 Floppy drive S2/S3
ABB 3HAB2480-1 Floppy drive S4
ABB 3HAB5386-1 Teach pendant S4
ABB 3HAC14441-9 CMOS-battery
ABB 3HNE00311-1 Teach pendant S4C
ABB 3HNE00313-1 Teach pendant S4C
ABB 4944016-2 Battery S3
ABB 4944026-2 Battery memory board S2
ABB YB161100-LH Teach pendant S2
ABB YB560100-EA Teach pendant S3
ABB YB560101-LA Power supply
ABB YT212002-BA Rectifier
ABB YT212002-C Rectifier
ABB YT212002-X Rectifier
ABB YB560103-CB DSQC236B DriveUnit
ABB YB560103-CC DSQC236C DriveUnit
ABB 3HAB2207-1 DSQC236D DriveUnit
ABB YB560103-CD DSQC236G DriveUnit
ABB 3HAB2207-1 DSQC236P DriveUnit
ABB YB560103-CE DSQC236T DriveUnit
ABB YB560 103-CL/5 DSQC241 PowerUnit
ABB 3HAB 2210-1 DSQC300 Robot Computer
ABB 3HAB 2216-1 DSQC314B PowerUnit
ABB 3HAB 2219-1 DSQC316 Main Computer
ABB 3HAB 2220-1 DSQC317 6MB Card
ABB 3HAB 2236-1 DSQC321 4MB Card
ABB 3HAB 5956-1 DSQC323 8MB Card
ABB 3HAB 5957-1 DSQC324 16MB Card
ABB 3HAB 2241-1 DSQC325 Main Computer
ABB 3HAB 2242-1 DSQC326 Robot Computer
ABB 3HAB7229-1 DSQC328 I/O Card
ABB 3HAB 6182-1 DSQC335 Robot Computer
ABB 3HAB8101-3/05D DSQC345B DriveUnit
ABB 3HAB8101-3/08C DSQC345C DriveUnit
ABB 3HAB8101-7/01C DSQC346C DriveUnit
ABB 3HAB8101-8 DSQC346G DriveUnit
ABB cable DSQC351 Interbus-S
ABB 3HAC 0373-1 DSQC361 Main Computer
ABB 3HAC3180-1 DSQC373 Robot Computer
ABB 900054 1Gb SD-card S3/S4 DDR
ABB 900056 1Gb SD-card S2 DDR
3HNE 00026 Teach Pendant
3HNE 00312-1 Teach Pendant
3HNE 00313 Teach Pendant
CHAA 3560-AXA Teach Pendant
ABB 3HAB9271-1/01B DriveUnit Dummy DriveUnit Dummy
ABB 57510001-AA DSCA 114 Print out board
ABB 57520001-U DSCA 121 Communication board
ABB 57160001-A DSDI 110 Digital input board
ABB 57160001-K DSDO 110 Digital output board
ABB YB161102-AH DSDX 110 Digital in/output board
ABB 57160001-TP DSDX B001 digital in-output board
ABB 57360001-U DSMB 124 Semiconductor memory board
ABB 57360001-AN DSMB 125 Semiconductor memory board
ABB 57360001-HG DSMB 127 Memory board
ABB 57330001-N DSMC 110 Floppy disk controller
ABB YB161102-AK DSPA 110 Axis computer
ABB 57310256-AF DSPC 150 Central processor
ABB 57310256-BA DSPC 153 Expand. single board computer
ABB 57310001-GP DSPC 157 Expand. single board computer
ABB YB161102-AD DSQC 103 Resolver power board
ABB YB161102-AF DSQC 105 Display board
ABB YB161102-BA DSQC 110 Programming board
ABB YB161102-BS DSQC 115 Resolver power board + 2 analogue
ABB YB161102-BE DSQC 116 Power supply
ABB YB161102-BG DSQC 117 Resolver power board
ABB YB161102-BU DSQC 124 Terminal unit
ABB YB161102-BV DSQC 129 R/D board
ABB YB161102-CH DSQC 136 Safety board
ABB YB161102-CM DSQC 138 Terminal unit
ABB YB560103-AC DSQC 202 Robot computer
ABB YB560103-AS DSQC 208A External axis board
ABB YB560103-AL DSQC 209 Analogue I/O board
ABB YB560103-AM DSQC 210 Safety board
ABB YB560103-AN DSQC 211 Power supply
ABB YB560103-BF DSQC 215 Robot computer
ABB YB560103-AZ DSQC 220 Programming board
ABB YB560103-BD DSQC 223 PC Board digital I/O
ABB YB560103-BE DSQC 224 PC Board combi I/O
ABB YB560103-BK DSQC 227 Winchester interface
ABB YB560103-BD DSQC 228 Safety board
ABB YB560103-BN DSQC 230 Robot computer
ABB YB560103-BS DSQC 233 External axis board
ABB YB560103-BY DSQC 235A Rectifier
ABB YB560103-BZ DSQC 235B Rectifier
ABB YB560103-CA DSQC 236A Drive unit
DSQC 236B Drive
ABB YB560103-CC DSQC 236C Drive unit
ABB 3HAB2207-1 DSQC 236D Drive unit
ABB YB560103-CD DSQC 236G Drive unit
ABB 3HAB2245-1 DSQC 236H Drive unit
ABB 3HAA3563-AJA DSQC 236P Drive unit
ABB YB560103-CE DSQC 236T Drive unit
DSQC 239 Board - ABB RIO
ABB DSQC 241 Power supply
ABB YB560103-CM DSQC 242 Programming board
