当然，并不是一切的PLC都有上述那么多类的指令，也不是有的PLC仅有上述几类指令。以上仅仅指出几个比方，阐明要从哪几个方面了解PLC指令，从中也可大致看出指令的多少及功用将怎么影响PLC的功用。
除了指令，为进行通讯，PLC还有相应的协议与通讯指令或指令，这些也反映了PLC的功用。
5.6支撑软件
为了便于编制PLC程序，大都PLC厂家都开发有关核算机支撑软件。
从本质上讲，PLC所能辨认的仅仅机器言语。它之所以能运用一些助记符言语、梯形图言语、流程图言语，以致高档言语，全赖为运用这些言语而开发的各种软件。

KEBA AR-181
KEBA CU312/E
KEBA CU313
KEBA CU313
KEBA CU313A
KEBA DI325
KEBA DI325
KEBA DI325
KEBA DO321
KEBA DO321
KEBA DO321
KEBA DO321/B
KEBA EC100S
KEBA PS244
KEBA SI232
KEBA TT 081  02203-7614
KENSINGTON WFH4C
KEPCO 4882-27
KEPCO BOP20-20M
KEYENCE ML-P2
KIDDE FENWAL 12-E27121-020-05
KNIEL CP15.6311-052-02
KOGANEI CS4HB
MOTOROLA MVME5100
MOTOROLA MVME5500
MOTOROLA MVME712/M
MOTOROLA MVME712M
MOTOROLA TMCP700 W33378F
MOTOROLA XVME-674
MOTOROLA XVME-957
MOTOROLA MVME147-013
MOTOROLA MVME162PA-344E
MOX MX603-0308-613
M-SYSTEM MD2202-D32-X-P
MTL 2213
MYKROLIS FC-280SAV
NACHI BUY222
NAICH AUX111
NATIONAL INSTRUMENTS SCXI-1163R
NATIONALA MM-4M-R
Natural?MicroSystems?NMS CG6500C 8E1/8T1 背板
NEC 136-551733-B-02
NEC 136-551735-D-04
NEC 136-551973-A-01   1月26日
NEC 136-553623-A-01
NEC FC  9821X
NEC FC-9821X
NEC G8NXAA5G
NEC NEC风扇
NEC PC-9821XB10
NEC PU-S24
NEC RSA-983/D
NEC SC-UPCIN-3
NI PCI-6031E
NI SCXI-1100
NI SCXI-1100
NI SCXI-1126
NIKON KBA-00650 4S007-320-A LC-SIG4
NMB-MAT 2410ML-05W-B50
NMS CG6060/32-4TE1
NOVELLUS 02-113640-00
OBERG INDUSTRIES F-DMDM-PM-110E
OKUMA ER-FC-2048D
OLEC 64VB412V02
OLYMPUS OTV-S7H-NA-12E
OMRON C200HG PA204S
OMRON C200H-ID217
OMRON C200H-OD219
OMRON C200HW-BC031
OMRON C200HW-NC113
OMRON E2G-M18KN10-WS-C1 2M
OMRON F350
OMRON F350-CEOV2
OMRON H3CR-A8E
OMRON HL-5000
OMRON HL-5030
OMRON MY-4J
ONLINE 56SAM-NEX
OPTIMATE OM1510
OPTIMATE OP-620
OPTO 22 SNAP-AITM-2
OPTO 22 SNAP-IDC5D
OTHER/其他 白棉
oxboro E69F-BI2-MS
OXIDE 0020-31655
PACFFFC PC832-001-T
PACIFIC SCIENTIFIC PC832-001-N
PACIFIC SCIENTIFIC T60-1001-C8-1A
PALCLEAN JD-BXG
PAPST TYP7114N/2
PARKER XPR10VT-4P3
PCCOOLER/超频三 CPU风扇
PELCO PA30-0065-00-A1
PHILIPS PR1613
PHOENIX FLMC10BASE-T/FO G850
PHOENIX HDFK4
PHOENIX IBS 24BK-I/O-T
PHOENIX PLC-BSC-24DC/21
PHOENIX QUINT PS-100-240AC/24DC/10
PHOENIX QUINT-PS-100-240AC/10
PHOENIX QUINT-PS-100-240AC/24DC/10
PHOENIX ST-SI-UK4
PHOENIX ST-SI-UK4
PHOENIX UK3N
PHOENIX UK4-T
PHOENIX UK6N
PHOENIX UT 4-HE SI
PHOENIX UT 4-MTD
PHOENIX UT 6-HE SI
PHOENIX IBS PCI SC/I-T
PILLAR INDUSTRIES AB7006-1
PILZ P1U-1NB
PILZ PZE3 V22 24VDC
PIONEER MAGNETICS PM1253AL-6-3-Z03
POLYSPEDE PRD2-200
POTTER&BRUMFIELD SDAS-01-7Y2S1024
POWER-ONE MAP55-1024
PROSOFT 1454-9F
PROSOFT 5601-RIO-MCM
Prosoft MVI56E-MCMR
PROSOFT MVI56-GSC
PROSOFT MVI69-PDPMV1
PROTECH SYSTEMS PBI-6SA
PRT PSA300R-81
PRT PSA300R-PFC
RADISYS EPC-16
RADISYS EPC-5 w/ EXM-13
RADISYS EXP-MX200
RELIANCE 0-51378-25
RELIANCE 0-56966-2
RELIANCE 0-57510
RELIANCE 0-57C400-A
RELIANCE 0-57C401-2
RELIANCE 0-57C402-C
RELIANCE 0-57C404-1E
RELIANCE 0-57C405-C
RELIANCE 0-57C406-E
RELIANCE 0-57C407-4H
RELIANCE 0-57C408-B
RELIANCE 0-57C411-2
RELIANCE 0-60002-6
RELIANCE 0-60010-E
RELIANCE 0-60031-5
RELIANCE 45C220B
RELIANCE 57C404C
RELIANCE 57C404C
RELIANCE 57C435
RELIANCE 803.65.00 BOARD
RELIANCE 805405-1R
RELIANCE DSA-MTR-600
RELIANCE E243
RELIANCE E372-013-404
RELIANCE F-4030-O-H00AA
RELIANCE H2310240032X512
RELIANCE S240-1A8
RELIANCE ELECTRIC 57C431
RELIANCE ELECTRIC 57C493
RELIANCE ELECTRIC WR-D4004
REXROTH 0608 801 006
REXROTH 608701018
REXROTH 608720040
REXROTH 608720040
REXROTH 608800048