每种型号的PLC的输入点数量是有规定的。对每一个尚未使用的输入点，它不耗电，因此在这种情况下，24伏电源端子向外供电流的能力可以增加般接受行程开关、限位开关等输入的开关量信号。输入接线端子是PLC与外部传感器负载转换信号的端口。输入接线，一般指外部传感器与输入端口的接线输入器件可以是任何无源的触点或集电极开路的NPN管。输入器件接通时，输入端接通，输入线路闭合，同时输入指示的发光二极管亮输入端的一次电路与二次电路之间，采用光电耦合隔离。二次电路带RC滤波器，以防止由于输入触点抖动或从输入线路串入的电噪声引起PLC误动作。
ADVANTEST R3261A SPECTRUM ANALYZER 9 kHz to 2.6 GHz     
      
 HP 8643A 0.26-1030MHz SYNTHESIZED SIGNAL GENERATOR w/OP     
      
 LIGHTPOINTE FLIGHT STRATA LFSA-0155-4KS-M3S WIRELESS     
      
 SONY TEKTRONIX AFG2020 ARBITRARY FUNCTION GENERATOR     
 250MS/s synthesized FUNCTION GENERATOR WITH OPT 02     
      
 HP 8349B 2GHz-20GHz MICROWAVE AMPLIFIER NICE CONDITION     
      
 JDS FITEL SB SERIES FIBER OPTIC  ABB DSQC129  SWITCH100-240V 50/60MHz     
      
 Hewlett-Packard / Agilent E5272A FRAME WITH E5281A UNIT     
      
 ALCATEL ATH Turbomolecular Pump     
      
 Tektronix SJ300E Sonet SDH Jitter Wander Analyzer      
      
 Hewlett Packard E8403A 75000 C-SIZE VXI MAINFRAME     
      
 Hewlett Packard E8403A 75000 ABB DSQC129   C-SIZE VXI MAINFRAME     
      
 ADVANTEST R3261A SPECTRUM ANALYZER 9kHz to 2.6GHz OPT15     
      
 HP 83430A LIGHTWAVE TRANSMITTER 1310.5nm W/ OPTION 130     
      
 HP 21242A 3.5/2.7MHz ULTRASOUND TRANSDUCER PROBE     
      
 HP 21200B 2.5MHz ULTRASONIC TRANSDUCER ULTRASOUND     
      
 HP 83430A LIGHTWAVE TRANSMITTER 1309.7nm W/ OPTION 130     
      
 AGILENT HP 85046B S-PARAMETER ABB DSQC129  TEST SET 300KHZ-2GHZ     
      
 ROHDE & SCHWARZ SMX SIGNAL GENERATOR 100KHz - 1000MHz     
      
 STROMAG STROMATIC ADC 012.3 V DIGITAL SERVO CONTOLLER      
      
 HP S5010 21347A 3.7/5.0 MHz Phased Array Sector      
      
 ANRITSU MS2601K SPECTRUM ANALYZER 9KHz-2.2GHz      
      
 KEPCO BOIPOLAR OPERATIONAL POWER SUPPLY BOP 500M     
      
 PENTAX EC-3400F VIDEO  ABB DSQC129  COLONOSCOPE FLAXIBLE ENDSCOPE      
      
 AGILENT 86061C 2x8 LIGHTWAVE SWITCH,115/230V, 50/60MHz.     
      
 HP 70004A DISPLAY FRAME AND HP70311A CLOCK SOURCE     
      
 HP AGILENT E6392B GSM MOBILE MS TEST SET WITH OPT 002     
      
 OLYMPUS CV-200 ENDOSCOPY VIDEO PROCESSOR UNIT WITH WIRE     
      
 BALDOR AC SERVO DRIVER SBSC2035 IN 320VDC OUT 0-250VAC      
      
 PHILIPS 21245A 5.0/3.7MHz ULTRASOUND TRANSDUCER PROBE     
      
 HP 70001A 8 SLOT SYSTEM  ABB DSQC129  MAINFRAME CHASIS WITH 70311A      
      
          TEKTRONIX TDS 520A TWO CHANNEL DIGITIZING 500MHz       
      
 OMRON CS1H-CPU66H PROGRAMMABLE CONTROLLER WITH MODULES      
      
 0.4X-2.5X KAPS BINOCULAR STEREOZOOM MICROSCOPE W/EYES.     
      
 Omron R88D-UA20HA AC ABB DSQC129  Servo driver 200V 11.0A 750W     
      
 ET EURO TEST EHV10/SL HIGH VOLTAGE TESTER