若主机单元的I/O数量不够用，可通过I/O扩展接口电缆与I/O扩展单元(不带CPU)相接进行扩充。 PLC还常配置连接各种外围设备的接口，可通过电缆实现串行通信、EPROM写入等功能。
编程器作用是将用户编写的程序至PLC的用户程序存储器，并利用编程器检查、修改和调试用户程序，监视用户程序的执行过程，显示PLC状态、内部器件及系统的参数等。
编程器有简易编程器和图形编程器两种。简易编程器体积小，携带方便，但只能用语句形式进行联机编程，适合小型PLC的编程及现场调试。图形编程器既可用语句形式编程，又可用梯形图编程，同时还能进行脱机编程。
Banner, T30UDPAQ, 55545, T30U Ultrasonic Proximity Switch Sensor
Allen Bradley, 42GRR-9000-QD, Photoswitch Transbeam Receiver
Siemens, RHOH4, MCCB Rotary Handle for Circuit Breaker
Watlow, 988A-10FD-AARG, Temperature Controller
Square D, 9007 EA-1, Lever Arm 3" Steel Roller
SANYO DENKI PMM-BA-5601 CONTROLLER
Advance, VCN-4P32, Centium Electronic Ballast 277V
Keyence GT-71A Gauge Sensor 24VDC
Turck, T8 L2 122 2211 0005, G Flow Amplifier
TOEI VLBST-Z04030-GU VRKF-LB-15C-400 (UNCLEAN) MOTOR
Parker 925520 Hydraulic Filter Element
ORIENTAL PH266-01M2 MOTOR
ORIENTAL BM MOTOR
Kooltronic, KB650S, Thin Fan 115V 50/60Hz
Nordson Corp Glue-OPS Nozzle dispenser
ORIENTAL SBMR501 BRAKE PACK
Kellems Strain Relief Wire Cable Grip .97-1.25" 1-1/4" Hubbell
SUPERIOR SS221 (UNCLEAN) MOTOR
Square D, 9070TF150D1, Industrial Control Transformer 150VA v
HARMONIC FHA-25C-100-E250-C AC SERVO ACTUATOR
Pilz, PZE9 VAC 8n/o 1n/c, Expansion Module
OMRON E5CS-R1G TEMPERATURE CONTROLLER
Allen Bradley, 800T-Q24A, Pilot Light Full Voltage 24V Amber Orange
Fanuc A20BA Circuit Board A20B
Advantech PCA-6157 P54 CPU Card
SUNX DPX-210B CONTOLLER
Telemecanique, GV2ME14, Circuit Breaker 600VAC 10Amp Schneider Square D
IFM Efector OGE701 Through-Beam Sensor Reciever Photoelectric 0GE701 OGELFPKG
Siemens, 3RK1301-0DB00-0AA2, DS1-X Motor Starter
Red Lion P Temperature Controller P48Series
ORIENTAL UPH566TG10-B2 MOTOR
PANASONIC M9MC90GB4CE M9GC150B (WITHOUT CONNECTOR) MOTOR
Allen Bradley, 800MR-D6AK, Pushbutton Mushroom Head Red Stop D6
Kooltronic, KB650S, Thin Fan 115V 50/60Hz
RKC REX-F400 CONTROLLER
Fanuc, A03B-0807-C011, PLC Interface Module AIF01A
UniPulse F366 Digital Indicator Control 10V Uni-Pulse Controller Display
Allen Bradley 836T-T253JX19 Pressure Switch Ser.A
Allen Bradley, 800T-XD2, Contact Block Shallow Block Push Button Switch