梯形图的编程方式是指根据功能表图设计出梯形图的方法。为了适应各厂家的PLC在编程元件、指令功能和表示方法上的差异，下面主要介绍使用通用指令的编程方式、以转换为中心的编程方式、使用STL指令的编程方式和仿STL指令的编程方式。
为了便于分析，我们假设刚开始执行用户程序时，系统已处于初始步（用初始化脉冲M8002将初始步置位），代表其余各步的编程元件均为OFF，为转换的实现做好了准备。
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1．使用通用指令的编程方式
编程时用辅助继电器来代表步。某一步为活动步时，对应的辅助继电器为“1”状态，转换实现时，该转换的后续步变为活动步。由于转换条件大都是短信号，即它存在的时间比它激活的后续步为活动步的时间短，因此应使用有记忆（保持）功能的电路来控制代表步的辅助继电器。属于这类的电路有“起保停电路”和具有相同功能的使用SET、RST指令的电路。
如图5-27a所示Mi-1、Mi和Mi+l是功能表图中顺序相连的3步，Xi是步Mi之前的转换条件。
图5-27 使用通用指令的编程方式示意图
编程的关键是找出它的起动条件和停止条件。根据转换实现的基本规则，转换实现的条件是它的前级步为活动步，并且满足相应的转换条件，所以步Mi变为活动步的条件是Mi-1为活动步，并且转换条件Xi＝1，在梯形图中则应将Mi-1和Xi的常开触点串联后作为控制Mi的起动电路，如图5-27b所示。当Mi和Xi+1均为“l”状态时，步Mi+1变为活动步，这时步Mi应变为不活动步，因此可以将Mi+1=1作为使Mi变为“0”状态的条件，即将Mi+1的常闭触点与Mi的线圈串联。也可用SET、RST指令来代替“起保停电路”，如图5-27c所示。
这种编程方式仅仅使用与触点和线圈有关的指令，任何一种PLC的指令系统都有这一类指令，所以称为使用通用指令的编程方式，可以适用于任意型号的PLC。
如图5-28所示是根据液压滑台系统的功能表图（见图5-26b）使用通用指令编写的梯形图。开始运行时应将M300置为“1”状态，否则系统无法工作，故将M8002的常开触点作为M300置为“1”条件。M300的前级步为M303，后续步为M301。由于步是根据输出状态的变化来划分的，所以梯形图中输出部分的编程极为简单，可以分为两种情况来处理：
1）某一输出继电器仅在某一步中为“1”状态，如Y1和Y2就属于这种情况，可以将Y1线圈与M303线圈并联，Y2线圈与M302线圈并联。看起来用这些输出继电器来代表该步（如用Y1代替M303），可以节省一些编程元件，但PLC的辅助继电器数量是充足、够用的，且多用编程元件并不增加硬件费用，所以一般情况下全部用辅助继电器来代表各步，具有概念清楚、编程规范、梯形图易于阅读和容易查错的优点。
2）某一输出继电器在几步中都为“1”状态，应将代表各有关步的辅助继电器的常开触点并联后，驱动该输出继电器的线圈。如Y0在快进、工进步均为“1”状态，所以将M301和M302的常开触点并联后控制Y0的线圈。注意，为了避免出现双线圈现象，不能将Y0线圈分别与M301和M302的线圈并联。
Torrington Sealed Cam Yok Roller Bearing YCRSC-32 YCRSC32 New
NEW ENDURO BEARING 30209
NEW TIMKEN TAPERED BEARING RACE 47620
NEW DODGE FLANGE BEARING SC 1-7/16
NEW MRC BEARING 5205CZZ-H501 5205CZZH501
New NBR Flange Bearing With NO Collar HC208-24 HC20824 FS208
New Fafnir Shielded Bearing 5207WD
Torrington Bearing NKJ12/16A NKJ1216A NK16/16A NK1616A New
HYATT PRECISION BALL & ROLLER BEARING 5202 NIB
NEW FAFNIR BEARING 304PP
NEW ConSOLIDATED THRUST BALL BEARING D-11 D11
FAG Self Aligning Ball Bearing 223/2310 2232310 New
NEW FAG 6208.C3 BALL BEARING 6208C3
Conveyor Roller Bearing MRK-80x2/6204 6204Z 3"OD Lot 4
NEW NTN BALL BEARING 60052C3 6005ZZC3/L627 6005ZZC3L627
NEW TIMKEN BEARING OUTER RACE 472D INNER RACE NA484
NEW MCGILL NEEDLE ROLLER BEARING MR-24 MR24
AMI Asahi Pillow Block Bearing MUC205FD MUC205-16 MUC20516 New
NEW KBC 6301Z BEARING 6301ZZC3G14
NEW SKF BEARING 7205 BECBY 7205BECBY
NEW FAG ADAPTER SLEEVE H 206 H206 "LOT OF 3"
NEW CARQUEST TAPERED ROLLER BEARING 07204 4T-07204 4T07204
NEW IKO CAM FOLLOWER BEARING CF10UUM
New AMI 2 Bolt Flange Bearing KHPFL204
NEW DODGE FLANGE BEARING LFSC100NL 124625
NEW JAF BALL BEARING 5304-2RS 53042RS
NEW BROWNING INSERT BEARING SLS-112 SLS112 3/4"
NEW NICE BEARING 1616 DS TNTG18 1616DSTNTG18
Gates PowerGrip V-Belt 270H150 New
NEW REXNORD ROLLER CARTRIDGE BEARING 5115
SKF Angular Contact Bearing 7308 BECBY 7308BECBY New
NEW TIMKEN 18620B TAPERED ROLLER BEARING RACE
SKF ROLLER BEARING 6004-2Z/C3GJN 60042ZC3GJN NEW
REXNORD 2 BOLT PILLOW BLOCK C251 0811 NIB
NEW SKF BEARING 6301-2ZJEM 63012ZJEM
NEW PEER BEARING 77R16 5664 77R165664
NEW NSK 6007N BEARING 25Z986D7
MRC R8FF BEARING R8-FF R8FF M31 H503 NEW
McGill Cam Follower Camfollower CFE 5/8 SB CFE58SB New
NEW MRC ROLLER BALL BEARING 38FF10 H001 38FF10H001
NEW SEALMASTER BEARING 720953 15/16" SK-1471 W/ COLLAR
RHP SELF-LUBE FLANGE BEARING SFT-25 SFT-3 1025 25 G NEW
PTI Shielded Roller Ball Bearing 1652 Z 1652Z Lot of 2 New
Torrington Inner Race Bearing IR-081212 IR081212 MS-51962-2 MS519622 New
NTN Tapered Roller Bearing 4T-15125 4FL29 NEW
NEW URB ROLLER BALL BEARING 1310
NEW INA IR25X3020.5 BEARING IR25X30205
NEW NSK SINGLE ROW RADIAL BALL BEARING 6206VVC3 6206V
SKF Self Aligning Double Row Ball Bearing 1215 KJ 1215KJ 1215K 75X13025MM New
AMI BEARING INSERT UC210-31 UC21031 NIB
NTN Rubber Sealed Ball Bearing 6205LLBC3/EM 6205LLBC3EM 6205C3 6205LB New
NEW "LOT OF 2" TIMKEN TAPERED ROLLER BEARING LM11910
NEW RHP INSERT BEARING 1035-1 3/16G 10351316G
MRC 310S ROLLER BEARING NEW
NEW ELGES BEARING GE 19 ZO GE19ZO
NEW ConSO THRUST BEARING 51107X
NEW FAFNIR BEARING 304K
Fafnir Ball Bearing 9105KDD 9105KDD C2 9105KDDC2 New
INA Needle Roller Bearing NCS 1412 A NCS1412A New
(2) Torrington Cam Follower Camfollower Bearing CR-14 CR14 7/8" New Lot of Two
NEW NICE 1633 DCTN BEARING 1633 1633DCTN
NEW FAFNIR 304PP BEARING 304-PP
NEW BROWNING BEARING LS-116 LS116
TRW MRC 202SFF4 (0019) BEARING NEW
NEW FAFNIR BEARING KSP10 FS 428 KSP10 FS428 KSP10FS428
SealMaster Seal Master Pillow Block Bearing EMP-31T EMP31T 1-15/16" Bore New
NEW GBC GENERAL BEARING CORP. BALL BEARING 21507-88-300 2150788300 16070C ON PKG
MRC Single Groove Radial Ball Bearing 309S New
NEW NSK 1202 SELF ALIGNING BALL BEARING
Timken Tapered Roller Bearing 582 New
NEW TYSON TAPERED ROLLER BEARING 07100
Hoover S-3604 Ball Bearing S3604 New
NEW NTN NEEDLE BEARING RNAO-1022x10x RNAO1022x10x
NDH Double Row Ball Bearing 1 # 55502 55502 5202 New
Farfnir Torrington Insert Bearing w/ Collar GRA100RRB+COL GRA100RRB New
Hub City Hubcity 2 Bolt Flange Bearing w/ Collar FB230X1/2 FB230 X 1/2 1/2" Bore
CUTLER HAMMER POW-R-LINE 4000A 4000 AMP 480/277V SWITCHBOARD BREAKER PANELBOARD
NEW NDH 1211TS 1211 TS 1211-TS CYLINDRICAL ROLLER BEARING
NEW NO NAME 22312W33C3 22312 W33 C3 ROLLER BEARING
NEW ConTINENTAL WEST BI-DIRECTIonAL PRECISION BEARING 1/CW 48 1/CW48 1CW48 OPN
NEW GENERAL BEARING ROLLER BEARING 23261-88-300 2326188300 3038DC
Westinghouse Heater 966472 AH1.5 New
BIMBA MRS-041.5-D STAINLESS S/S 5 3/4" - 7 1/4" AIR PNEUMATIC CYLINDER NEW
NEW FAFNIR BEARING 9109KG
NEW SMT BEARING SR-20 SR20
MRC Double Row Ball Bearing 5209M Made in USA 45X85MM New
NEW DODGE LFTSC100 MOD FLANGE BEARING SIZE 1" BORE SC 1-205 LFTSC100
NEW TORRINGTON / INGERSOLL RAND NTA-815 THRUST BEARING NTA815
Justrite Dual Action Drum Vent 8-005 8005 Non-metallic New
NTN Bearing 526207U
SKF ADAPTER SLEEVE H 206 H206
NEW SKF ADAPTER H305
FEDERAL MOGUL 15243 BEARING NEW
NEW ConSOLIDATED PRECISION BEARING 95432
Igus DrylLin T Linear Rail Guide Rail Car TW-01-20 TW0120 New
Consolidated Cam Follower Bearing CRSB-14 CRSB14 New
NEW RCBD BEARING 62072RSC3
NEW KILLIAN BEARING F350-13 F35013
NEW TIMKEN FAFNIR BEARING 204PP P204PP
NEW NKB BALL BEARING INSERT UC 204-20MM UC20420MM UC204
NEW HLU PILLOW BLOCK BEARING NAPL204-12 NAPL20412 NA204-12 NA20412
NEW SNR BEARING 6007.ZZJ30D43A50 6007J30D43 6007ZZJ30D43A50
HBC Rubber Sealed Ball Bearing S60112RS S6011RS New
SKF Ringcamf Cam Follower IR 25X32X22 IR25X32X22 New
Timken Tapered Roller Bearing Cup and Cone 3720 3778-MM 3778MM New
Fafnir G1014KRRB + COL AG Farm Bearing W/ Collar New
NEW IBI PILLOW BLOCK BEARING HCAK204-12 NA204-12U
link-Belt Insert Bearing U 215 D U215D 15/16" Bore New
NEW NO NAME LAU1/2 INTERCHANGABLE HUB BORE 1/4" BORE
FAFNIR BALL BEARING S10P S10P C3 S10PC3 NIB
NEW AMI BEARING UCC202
SealMaster Insert Bearing SL-10 SL10 New
NEW MRC BEARING 202FS5
CASCADE 55F-FPS-A149P1 5500LB LIFT TRUCK CLASS II SIDE SHIFT FORK POSITIonER NEW
PEER Flange Bearing UCFT201-8 UCFT2018 New
Browning 4020 X 5/8 Sprocket 4020-5/8 4020 5/8 New
NEW MRC BEARING 206SFFC 206SFFC H401
Timken Inner Race IR-1012-OH IR1012OH New
NEW TIMKEN TAPERED ROLLER BEARING LM48510
NEW SPHERCO ROD END BEARING TRE5
NEW ANDREWS 08Y42 BALL BEARING
NTA THRUST BEARING NTA-2435 NTA2435 4L NEW
Nice Roller Ball Bearing No 703 No703 New
IKO CAM FOLLOWER CR 26UU CR26UU NIB
NEW BOSTON GEAR KEYED BORE SPUR GEAR NB80 072905 5/8" BORE 3/16" KW
NSK BEARING 6305VVC3 6305V NIB
NSK 6008TCG12P4 Super Precision Bearing 6008TCG12P4 New
Gulf Adapter Sleeve H-206x25 H206x25 H20625
NEW FAFNIR BALL BEARING PS3K
Dodge Aluminum Bearing Seal LER103 New
NEW ANDREWS 909 THRUST BEARING
Fafnir Torrington Sealed Ball Bearing 302KDD 302KDD C1 Lot of 2 New
NEW DEPARTURE HYATT BEARING Z993L09
Fafnir Roller Ball Bearing 203KD5 NEW
NEW HEPCO JA-10-C LINEAR DOUBLE BEARING JA10C
Fafnir 2MM9103WI DUL Super Precision Bearing Set 2MM9103WIDUL New
NEW SKF ROLLER BALL BEARING 6209 M212 6209M212
MRC Single Row Ball Bearing 207 SFFC 207SFFC New
5 New McNeil Akron Spring Extension 8 Coil 1-3/4 Q14614
NEW TIMKEN TAPERED ROLLER BEARING W/RACE 32206 91H50 X-32206 32206
NEW MRC BEARING 115KSZZ
NEW MRC BEARING 7212 7212DU
Asahi Insert Bearing UC208 New
NEW INCOM SPROCKET 35B25 1/2" BORE
Asahi Insert Bearing UC208 New
NEW INCOM SPROCKET 35B25 1/2" BORE
NEW FLEXCO NYLON COVERED STEEL CABLE HINGE PIN 38008 NC-36-1 1/4" DIAMETER NC361
NTN PILLOW BLOCK BEARING HP206 UC206 NEW
NEW INA NEEDLE BEARING SCE610PP CPNO: 408676
NEW INCOM SPROCKET 40B12 1/2" BORE
McGill Caged Needle Roller Bearing MR-12-SS MR12SS New
NEW NO NAME BEARING 608RS "LOT OF 4"
SKF 4 Bolt Flange Bearing w/ Collar FY 1.7/16 FM VCJ 1 7/16 VF-23 E VF4E-123 New
RBI 1654ZZ BEARING NEW
NEW MRC BEARING 306 MF 306MF
NEW SKF BEARING RNU 204 RNU204
NSK Needle Bearing LB3200B2RSRSTNG P New
NEW MRC BEARING 104 KSZZ 104KSZZ
NEW CARTER CNB-28-S CAM FOLLOWER CNB28S
Torrington Bearing Inner Ring IR-212616 IR212616 MS51962-17 New
TORRINGTON NEEDLE BEARING JT-1211 JT1211 NIB
New MRC Bearing 112KSFF-0024 112KSFF-0024C3 Steel ABEC1
SKF Sealed Ball Bearing 630Z/C3 630ZC3 630Z C3 New
No Name Single Row Ball Bearing 9RS MXS New
NEW MARTIN SPLIT TAPER BUSHING 3020 2-7/16" 2 7/16" 2716
(10) IKO Inner Race IRB 1012 OII IRB1012OII Lot of 10 New
Nachi Sealed Rubber Ball Bearing 6300NSE C3 6300NSEC3 New
NEW FAFNIR BEARING 9103 K C1 9103KC1
NEW LOT OF 2 KYK BEARING SSR4A-ZZ SSR4AZZ
SIEMENS HF361R 30A 30 A AMP 600V TYPE 3R FUSIBLE SAFETY DISConNECT SWITCH NEW
NEW FAFNIR SUPER PRECISION BEARING MM311K CR MM311KCR
Fafnir Roller Ball Bearing 214KDD NEW
FEDERAL-MOGUL BEARING 5205-KSSE 5205KSSE 5205CZ NIB
NEW MCGILL MI-19 INNER RACE BEARING MI19
No Name Spherical Roller Bearing 1204 New
NEW TIMKEN 1220 TAPERED OUTER RACE BEARING
SKF Ball Bearing 108 TN9 108TN9 New
Timken Bearing Cone Outer Race 373 New
NEW FAFNIR ROLLER BEARING PM9105K
RBC BEARING IR7154 IR-7154 C15 NIB
NEW KBC RUBBER SEALED BEARING 6012D
McGill Inner Race Bearing MI-27 MI 27 MI27 New
NEW INA BEARING IR8X12X12
NEW INA FLANGE BEARING RME35 01ME07 GE35KRRB
NEW SNR 6004 BALL BEARING 6004 F82
NEW Hi-Light USA Pillow Block Bearing SAPL208-24G
SKF BJ2-4014 Bearing BJ24014
Fafnir 9111KG Ball Bearing 9111-KG New
NEW MRC 5303SBKF BEARING TRW 5303 SBKF
INA BK3016 Needle Bearing BK 3016 New
NEW MRC BEARING 203S 0058 203S0058
SCHATZ BR9905 BALL BEARING NEW