系统程序是PLC赖以工作的基础，采用汇编语言编写，在PLC出厂时就已固化于ROM型系统程序存储器中。
系统程序分为系统监控程序和解释程序。
系统监控程序用于监视并控制PLC的工作，如诊断PLC系统工作是否正常，对PLC各模块的工作进行控制，与处设交换信息，根据用户的设定使PLC比处在编制用户程序状态或者处在运行用户程序状态等。
解释程序用于把用户程序解释成微处理器能够执行的程序。来自PLC之家
输入接口 用于接收输入设备（如：按钮、行程开关、传感器等）的控制信号。
Graco, Bulldog Pump Repair Kit
TELTEC REV Y REV K BOARD
Murr, , Elektronik Exact 8 Profibus Module Devicenet Block
IFM Efector E10731 Proximity Switch Sensor Mounting Bracket
OMRON R88M-U20030HA-BS1 (BROKEN) AC SERVO MOTOR
RORZE RC-234 GENERATE MASTER
HAKKO GD-80E020J-G-08 TOUCH SCREEN
YASKAWA SGD-01BPY10 SERVOPACK
Ohmite lug resistor L100J15k 100w 15000 ohm 100 watt
Baldor, 34AG3, Motor .5HP 1/2hp 208v 200v 1725rpm 3PH TEFC CM3538
PCB Piezotronics 352A76 Accelerometer Vibration Sensor 56970
Motorola, MC68010L10, Microprocessor Microcontroller 32bit Chip
YASKAWA SGM-01A314B AC SERVO MOTOR
Keyence, FS2-60, Proximity Switch Photoelectric Sensor
Yaskawa, JARCR-XOI01B, XOIO1B, XOI01B Input Output Motoman Robot PC Board Rev. B
GE Fanuc A16BB PMC Card PCB control Board
Square D 9001K1L Push Button Ser.J
Watts Fluidair EK602VB Purge Air Particulate Element Filter 5 micron pneumatic
SHINANO STH-56D118 MOTOR
Allen Bradley, 42KB-S2LPSA-A5, Photoelectric Sensor Switch
Falk Input Coupling Kit CKTC
Turck BC10-M30-VN4X Inductive Proximity Switch Sensor Position 25021 10-65VDC
ABB Sace Tmax T2H Circuit Breaker 3Pole TMF 100a 100 amp
ATLAS AHD70C4-44S GPL.5:1 AC SERVO MOTOR
TELTEC REV D REV A BOARD
IFM, IA-3010-BPKG, Efector Proximity Sensor Switch
NISSEI F2SMT60T (BROKEN) INDUCTION MOTOR
Copeland, , Contactor 30Amp
Yokogawa 254 Percent Tension Panel Meter 0-10VDC 0-100% 046441 RAM
Exlar, GSDM-MD1-M6, 15075, 0DM Linear Servo Actuator Motor Drive 2400rp
Square D 9999R8 Disconnect Interlock Switch 9999-R8
Hubbell HBL5965VYCN 5965VYCN Plug Valise 15A 125V 120v Extension Cord Male Cable
PITTMAN GM9413C292 (UNCLEAN) MOTOR
Siko MSK Position Sensor 24VDC
Siemens, 6ESBB50-0XA0, Simatic Bus Connector
ORIENTAL PH569-A VEXTA STEPPING MOTOR
Moeller, DP-32DI/P-ECO, Profibus DP WINBloc ECO Compact Module
Square D EK1020-2 Electrical Interlock Switch Kit
