独立型PLC又称外装型或通用型PLC。对数控机床而言，独立型PLC独立于CNC装置，具有完备的硬件结构和软件功能，能够独立完成规定的控制任务。采用独立型PLC的数控系统框图（如图1所示）。
图1 独立型PLC的CNC系统框图
独立型PLC具有如下特点
(1)独立型PLC具有CPU及其控制电路，系统程序存储器、用户程序存储器、输入／输出接口电路、与编程器等外部设备通信的接口和电源等基本功能结构SYSTEMbase E-G900-05-4605(A) MULTI-8/LPCI MULTI8LPCI
TOYO I/F BOARD-4-(A) P1A00371 I/F BOARD4(A) P1A00371
TPC UC24 RF4-04G RF-04D RF404G RF04D
USHIO INC / FR-4 SEK-K / PB0068
VOX TECHNOLOGIES SBC BOARD SUPERQ965
XPAC 32 CH D/I I-87040W
XPAC 32 CH D/O I-87041W
FUJIKIN DIAPHRAGMSOFT-SEAL DIAPHRAGMSOFTSEAL
IMAGING TECHNOLOGY PCVISION R-B L8 5300-000
[TEST VIDEO] YASKAWA SERVOPACK SGDA-02BS
3COM ETHERlink XL PCI 3C900-COMBO 03-0108-002
ALCATEL ANNECY 110713-A 110986
ALCATEL ANNECY 114507
ALCATEL ANNECY 121971
ALCATEL ANNECY P0263
ASM 03-20497-03
B&R AUTOMATION PC 5PC810.SX02-00
CASUH DSRC REV 1.1 DSRC REV 11
ConDOR POWER SUPLLYS 24V 6.7A GPM140-24
DAEDONG SAVV 10.3" DIGITAL TFT LCD COLOR TV LTV-1040/NTSC
EPICO Treadmill Inverter ETI-371I
ESI VME/MMB INTERFACE CKA 77288D
FUJI IS70B JZMMC-IS70B DF9200143-B0
FUJIKIN T1000L MASS FLOW FCST1005LUC-4J2-F100-N2
GO ELEMENT GO-PT101
HANYONG AREA SENSOR PAN20-TR16N
ICP POWER SUPPLY ACE-870A
KDT SYSTEMS CYMON CM1-AD08V
KDT SYSTEMS CYMON CM1-TC04A
KDT SYSTEMS CYMON CM1-XA08A
KODAK EKTASCAN KEYPAD 3140
LS ENET I/F XGL-EFMT
LUST KP200
MITSUBISHI AC SERVO MR-J2S-100B-EG
MUSASHI CB-PG4
NEMIC-LAMBDA CKS-5-150A
NSK ESB SERVO DRIVER ESB-YSB2020AB300-00.1
OMRON NC UNIT C200H-NC211 C200HNC211