PLC是采用“顺序扫描,不断循环”的方式进行工作的。即在PLC运行时,CPU根据用户按控制要求编制好并存于用户存储器中的程序,按指令步序号(或地址号)作周期性循环扫描,如无跳转指令,则从**条指令开始逐条顺序执行用户程序,直至程序结束。然后重新返回**条指令,开始下一轮新的扫描。在每次扫描过程中,还要完成对输入信号的采样和对输出状态的刷新等工作。
PLC的一个扫描周期必经输入采样、程序执行和输出刷新三个阶段。
PLC在输入采样阶段:首先以扫描方式按顺序将所有暂存在输入锁存器中的输入端子的通断状态或输入数据读入,并将其写入各对应的输入状态寄存器中,即刷新输入。随即关闭输入端口,进入程序执行阶段。
Mondi Apttee 250DI 3 Flanged Straight Tee 7-1/2 OD 4 Bolt
Moon J-81 Straight Tooth Milling Cutter 4 x1 Bore 1 Width
Moons Hybrid Stepping Motor 2-Phase BI-Polar 1.8 Deg Angle 1/4 Shaft Dia 23HM
Moore 13660-1 Linear Transducer Probe Gage Sensor w/ 5 pin Male End
Moore 13660-1 Linear Transducer Probe Gauge Sensor w/ 5 Pin Female Plug
Mori Seiki AP-DTP-AD2 E76042A01 Circuit Control Board
Mori Seiki G21034A Gear 33mm dia 16mm wide 13mm shaft size
Mori Seiki SL200 Ballscrew & Nut W/End Bearing & Servo Housing CNC Lathe
Morris BL6 46-1/2 Steel Leaf Chain Standard Riveted Chain ANSI Size 3/4 Pitch
Morse .9928 HSS straight 8 flute chucking reamer 10-1/2 OAL re-sharp
Morse 100-1 C/L 332283 Roller Chain Connecting Link C/L C/P S/F 1.1250 Pitch
Morse 100-1 C/L 332283 Roller Chain Connecting Link C/L C/P S/F 1.1250 Pitch
Morse 100523 500TL 2-15/16 ID Disk Spring Limiter Clutch/Brake
Morse 1008x15/16 Taper-Lock Bushing 15/16 Bore NIB
Morse 1008x15/16 Taper-Lock Bushing 15/16 Bore NIB
Morse 120 C/L 332284 Roller Chain connecting Link C/P S/F 1-1/2 Pitch Cottered
Morse 15GED ED Series Speed Reducer Gear Box 10:1 Ratio 175 RPM 56C Frame
Morse 15GED ED Series Speed Reducer Gear Box 10:1 Ratio 175 RPM 56C Frame
Morse 175Q56LR60 Raider 60:1 Dual output 56C Gear Box Speed Reducer Worm Gear
Morse 18GED Speed Reducer Gear Box 15:1 Ratio 117 RPM 56C Frame Right Hand
Morse 21L-T 1-LR Speed Reducer Gearbox 29:1 Ratio 3/4 Dual Output
Morse 80 Single Strand Riveted Roller Chain 1 Pitch 10' Length
Morse BL-6 Leaf Chain 4x6 Lacing 3/4 Pitch 5Ft Length
Morse Tape Inspection Gauges 1MT - 4MT Male & Female Plug Gauge Tool 8pc Set
Morse Taper Extension Sleeve MT4 to MT4
MORSE/AP 3/4 #2 MT SS SF Chucking Reamers Lot/7 Various Mfg.
Motorschutz Kriwan 13A127S21 Motor Protector
Motovario PH/083 C-Face In-Line Helical Gear Reducer Box 195:1 Ratio 56C
MPB Andrews Bearing CO. RTL9 Bearing
MRC 206SH201C3 Bearing
MRC 206SH201C3 Bearing
MRC R4AFF Radial/Deep Groove Ball Bearing Doubled Shielded Lot of 2
MRC R4Z H401 Sealed Ball Bearing
MSC PIC645 Switching Regulator
MTE P201-3386 Four Section Rotary Gear Hydraulic Flow Divider 1/4 Inlet
MTH Pumps 142IA BF Regenerative Turbine Pump 1-1/4 Intake & Outlet 3/4 Shaft
Mueller AC17864 7/8 Ball Valve Assy w/Access Solder Connections
Muller Galvanized Pipe Nipple, 1/2 npt x 5 Long Schedule 40 Lot of 11
Muller Galvanized Pipe Nipple, 1/2 npt x 5 Long Schedule 40 Lot of 11
Multi Purpose White Rubber Conveyor Belt 1-13/16 x20' Long 0.10 Thick
Multi-Wing 32 Medium Volume 6 Blade Axial Fan 40 Deg. W/ Taper Lock Mount Hub
Murr Electronik MCS5 Art No 85084 Switch Mode Power Supply Parts or Repair
MW Hydraulik 351-115 Type HMS-V20 Hydraulic Axial Piston Motor HMSV-20
Myron Zucker 243VLM Calvault Capacitor 480V 3Ph 60Hz 2KVR
Myron Zucker KIM43003-3 Ser.Calmount Power Factor Correction Capacitor 3PH 480V
Nachi BT50-JTA6-105 BT50 Jacobs Taper Adapter 105mm Projection w/ Chuck
Nachi S-1491-5 Single Position Hydraulic Manifold / Valve Block
Nagano Keiki CQ20 Pressure Switch
Namco CA210-40012 Absolute Encoder Digital LED Display Module ABS/ENC 115/230VAC
Napa 1069 Gold Oil Filter |