(二) 用戶程序履行時期
在用戶程序履行時期，PLC老是按由上而下的次第順次地掃描用戶程序(梯形圖)。在掃描每一條梯形圖時，又老是先掃描梯形圖左邊的由各觸點構成的操控線路，并按先左后右、先上后下的次第對由觸點構成的操控線路進行邏輯運算，然后依據(jù)邏輯運算的成果，改寫該邏輯線圈在體系RAM存儲區(qū)中對應位的狀況；或許改寫該輸出線圈在I/O映象區(qū)中對應位的狀況；或許斷定是不是要履行該梯形圖所規(guī)則的特別功用指令。
即，在用戶程序履行進程中，只需輸入點在I/O映象區(qū)內(nèi)的狀況和數(shù)據(jù)不會發(fā)作改變，而別的輸出點和軟設備在I/O映象區(qū)或體系RAM存儲區(qū)內(nèi)的狀況和數(shù)據(jù)都有也許發(fā)作改變，并且排在上面的梯形圖，其程序履行成果會對排在下面的凡是用到這些線圈或數(shù)據(jù)的梯形圖起作用；相反，排在下面的梯形圖，其被改寫的邏輯線圈的狀況或數(shù)據(jù)只能到下一個掃描周期才干對排在其上面的程序起作用。
(三) 輸出改寫時期
當掃描用戶程序完畢后，PLC就進入輸出改寫時期。在此時期，CPU依照I/O映象區(qū)內(nèi)對應的狀況和數(shù)據(jù)改寫一切的輸出鎖存電路，再經(jīng)輸出電路驅(qū)動相應的外設。這時，才是PLC的真實輸出
同樣的若干條梯形圖，其擺放次第不一樣，履行的成果也不一樣。別的，選用掃描用戶程序的運轉成果與繼電器操控設備的硬邏輯并行運轉的成果有所區(qū)別。當然，假如掃描周期所占用的時刻對全部運轉來說能夠疏忽，那么二者之間就沒有什么區(qū)別了。
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
