IC693MDL940RR
PLC的工作方式为扫描加中断，这既可保证它能有序地工作，避免继电控制系统常出现的"冒险竞争"，其控制结果总是确定的；而且又能应急处理急于处理的控制，保证了PLC对应急情况的及时响应，使PLC能可靠地工作。
为监控PLC运行程序是否正常，PLC系统都设置了"看门狗"（Watchingdog）监控程序。运行用户程序开始时，先清"看门狗"定时器，并开始计时。当用户程序一个循环运行完了，则查看定时器的计时值。若超时（一般不超过100ms），则报警。严重超时，还可使PLC停止工作。用户可依报警信号采取相应的应急措施。定时器的计时值若不超时，则重复起始的过程，PLC将正常工作。显然，有了这个"看门狗"监控程序，可保证PLC用户程序的正常运行，可避免出现"死循环"而影响其工作的可靠性。
PLC还有很多防止及检测故障的指令，以产生各重要模块工作正常与否的提示信号。可通过编制相应的用户程序，对PLC的工作状况，以及PLC所控制的系统进行监控，以确保其可靠工作。
PLC每次上电后，还都要运行自检程序及对系统进行初始化。这是系统程序配置了的，用户可不干预。出现故障时有相应的出错信号提示。
正是PLC在软、硬件诸方面有强有力的可靠性措施，才确保了PLC具有可靠工作的特点。它的平均无故障时间可达几万小时以上；出了故障平均修复时间也很短，几小时以至于几分钟即可。
曾有人做过为什么要使用PLC的问卷调查。在回答中，多数用户把PLC工作可靠作为选用它的主要原因，即把PLC能可靠工作，作为它的**指标。
机型选择的基本原则是在满足功能要求及保证可靠、维护方便的前提下，力争**的性能价格比。
Weinschel 24-3-55 DC to 8.5 GHz, 3 dB, 50 Watts, APC-7 to APC-7 Attenuator
Weinschel 24-3-55 DC to 8.5 GHz, 3 dB, 50 Watts, APC-7 to APC-7 Attenuator
Weinschel 24-6-11 DC to 8.5 GHz, 6 dB, 50 Watts, 2.92 mm (F-F) Coax Attenuator
Weinschel 24-6-55 DC to 8.5 GHz, 6 dB, 50 Watts, APC-7 to APC-7 Coax Attenuator
Weinschel 3200-1, DC to 2 GHz, 127 dB, 50 Ohm, SMA (F) Programamble Attenuator
Weinschel 3200-1, DC to 2 GHz, 127 dB, 50 Ohm, SMA (F) Programamble Attenuator
Weinschel 3201-4, DC to 2 GHz, 0 to 1.2 dB, SMA (F) Programmable Step Attenuator
Weinschel 3206-1E-2 0 to 2000 MHz, 50W Attenuator (Pins Broken Off)
Weinschel 3210 Attenuator Controller
Weinschel 33-15-43, DC to 8 GHz, 15 dB, 25 W, 1.3 VSWR, Type N (M-F) Attenuator
Weinschel 37-10-34, DC to 8.5 GHz, 10 dB, 10 W, Type N (M-F) Coax Attenuator
Weinschel 37-20-34, DC to 8.5 GHz, 20 dB, 10 W, Type N (F-M) Coax Attenuator
Weinschel 3M-8, DC to 12.4 GHz, 8 dB, 2 Watts, SMA (M-F) Coaxial Attenuator
Weinschel 3M-8, DC to 12.4 GHz, 8 dB, 2 Watts, SMA (M-F) Coaxial Attenuator
Weinschel 3T-3, DC to 12.4 GHz, 3 dB, 2 W, SMA (M-F) Fixed Coaxial Attenuator
Weinschel 3T-4, DC to 12.4 GHz, 4 dB, 2 W, SMA (M-F) Fixed Coaxial Attenuator
Weinschel 41-8-12, DC to 18 GHz, 8 dB, 10 W, 50 Ohm SMA (M-F) Coaxial Attenuator
Weinschel 45-40-33, DC to 1.5 GHz, 40 dB, Type N (F) Coaxial Attenuator, !
Weinschel 46-20-34, DC to 18 GHz, 20 dB, 25 W, Type N (F-M) Coax Attenuator
Weinschel 49-40-43 DC to 8.5 GHz,150 W, 40 dB, High Power Attenuator, N (m-f)
Weinschel 4M (1 dB) DC to 18 GHz, 1 dB, 2W, SMA, Fixed Coaxial Attenuator
Weinschel 50-10 DC to 3 GHz, 10 dB, 1 W, 50 Ohm,Type N (M-F) Fixed Attenuator
Weinschel 50-2 DC to 3 GHz, 2 dB, 2 Watts, 50 Ohm, Type N (M-F) Fixed Attenuator
Weinschel 50-20 DC to 3 GHz, 20 dB,1 W, 50 Ohm,Type N (M-F) Fixed Attenuator
Weinschel 50-3 DC to 3 GHz,3 dB, 2 Watts, 50 Ohm, Type N(M-F) Coaxial Attenuator
Weinschel 50-30, DC to 3 GHz, 30 dB, 1 W, 50 Ohm, Type N (M-F), Fixed Attenuator
Weinschel 50-5 DC to 3 GHz, 5 dB, 2 Watts, 50 Ohm,Type N (M-F) Fixed Attenuator
Weinschel 50-6 DC to 3 GHz, 6 dB, 2 Watts, 50Ω, Type N (M-F) Fixed Attenuator
Weinschel 530-6, 1.0 to 10.0 GHz, 6 dB, 2.5 W, Type N, Fixed Coaxial Attenuator
Weinschel 530A-10 1.0 to 12.4 GHz,10 dB, 2 Watts, Type N (M-F) Fixed Attenuator
Weinschel 530A-2, 0.5 to 10 GHz, 2 dB, 5 W, Type N (M-F) Coaxial Attenuator,
Weinschel 535-FN DC to 12.4 GHz, 1 Watt, Type N (F), Coaxial Termination
Weinschel 535-MN, DC to 12.4 GHz, 1 W, 50 Ohm, Type N (M), Coaxial Termination
Weinschel 55-10 DC to 18 GHz, 5 Watt, 1 KW Peak, 10 dB, TNC (M-F) Attenuator
Weinschel 5873A, DC to 4 GHz, 0 to 70 dB, 12 VDC SMA (F) Programmable Attenuator
Weinschel 650-15, DC to 5 GHz, 15 dB, Type N (M-F) Fixed Coaxial Attenuator
Weinschel 73-30-33 DC to 8.5 GHz, 30 dB, 100 Watts, Type N (F-F) Coax Attenuator
Weinschel 74-10-12, DC to 28 GHz, 10 dB, 25 W, 3.5mm (M-F) Coax Attenuator
Weinschel 74-10-12, DC to 28 GHz, 10 dB, 25 W, 3.5mm (M-F) Coax Attenuator
Weinschel 907A-10-11, DC to 2 GHz, 10 dB, SMA (F-F) Variable Attenuator
Weinschel 936N 10 MHz to 12.4 GHz, Noise Suppressor
Weinschel 9426, DC to 1.0 GHz, 0 to 15 dB, 1W, SMA, 50 ohm, Variable Attenuator
Weinschel 953-10, 2.5 to 11 GHz, 10 dB, 1 W, Type N (M-F), Variable Attenuator
Weinschel 973-20, 1.5 to 11 GHz, 20 dB, 1 W, Type N (M-F) Variable Attenuator
Weinschel 973-20, 1.5 to 11 GHz, 20 dB, 1 W, Type N (M-F) Variable Attenuator
Weinschel LN-10 DC to 1 GHz, 10 dB, 1 Watt, Type N (M-F), Coax Fixed Attenuator
Weinschel M1418 DC to 18 GHz, 10 Watts, Type N (M) Coaxial Load
Weinschel M1418 DC to 18 GHz, 10 Watts, Type N (M) Coaxial Load
Weinschel M1426 DC to 8.5 GHz, 50 Watt, Medium Power Coaxial Termination (!)
Weinschel M1426 DC to 8.5 GHz, 50 Watt, Medium Power Coaxial Termination (!)
Weinschel Model 6, DC to 8 GHz, 10 dB, 20 W, Type N (M-F) Coaxial Attenuator
Weinschel Model 6, DC to 8 GHz, 10 dB, 20 W, Type N (M-F) Coaxial Attenuator
Weinschel WA40-40-12 DC to 8.5 GHz, 150 Watts, 40 dB, SMA (M-F) Coax Attenuator
Weinschel WA49-20-34, DC to 8.5 GHz, 20 dB, 150 W, Type N, Coaxial Attenuator
Weinschel WA49-40-34, DC to 8.5 GHz, 150 Watts, 40 dB, Type N (F-M) Attenuator
Weinschel WA49-40-34, DC to 8.5 GHz, 150 Watts, 40 dB, Type N (F-M) Attenuator
Weller WRS1002 120 VAC, 50/60Hz, 175 Watt, Self Contained Hot Air Rework Station
Weller WSA350, 120 VAC, 20W, 50/60 Hz, ESD Safe, Benchtop Smoke Absorber + Box
Weller WSA350, ESD Safe, Smoke Absorber, For Solder Fumes + Filter & Manual
Weller/Ungar 4024-0 120 VAC, 50/60Hz, 1 Amp In, 24V 2 Amp Out, Soldering Station
Weller/Ungar 4024-0 120 VAC, 50/60Hz, 1 Amp In, 24V 2 Amp Out, Soldering Station
Wentworth PV0195RH Vacuum base, Right Handed, XYZ, High Res Micropositioner
Wesco Monogram MRT550BF Pneumatic Right Angle Torque Responsive Tool w/Adapter
Wester Digital Caviar 31200 (99-004181-000), 1.2 GB, AT / IDE, 3.5" Hard Drive
Western Digital Caviar 28400 (AC28400-32RTT2) 8.4 GB, ATA / IDE, 3.5" Hard Drive
Western Digital Caviar WD100, 10 GB, 7200 RPM, ATA / IDE, 3.5" Hard Drive
Western Digital Caviar WD200 (WD200BB-75AUA1), 20 GB, ATA / IDE, 3.5" Hard Drive
Western Digital Caviar WD400, 40 GB, ATA / IDE, 3.5" Hard Drive, -Refurb!
Western Digital WD400 Caviar, WD400BB-75FJA1, 7200 RPM, 3.5", 40 GB Hard Drive
Western Electric (IFI) 242-03, Psychro-Dyne Wet/Dry Bulb + Case, 2 Bulbs, Wick
Western Electric 1BXDCR, 4.9 to 7.05 GHz, WR159, Waveguide to Coaxial Adapter
Western Electric 1DXDCR, 4.9 to 7.05 GHz, WR159, Waveguide to Coaxial Adapter
Western Industrial Products (WIP) Ser 200 "Strip-Pro" Air Powered Wire Stripper
Westinghouse SureTest 2400 MIL-STD-1553 Bus Analyzer/Emulator, Complete + Accy's
Westinghouse SureTest 2400 MIL-STD-1553 Bus Analyzer/Emulator, Complete + Accy's
Weston KS9442-L2, 25 Amp / 50 mV, 50 Amp / 100 mV, Current Shunt
Whitey (Swagelok) SS-63TSW12T, 3/4", 316SS, Series 60 Ball Valve, in Box
Whitey Swagelok SS-62XTF4, 1/4" FNPT, 316 SS, 3 Way Ball Valve Assy, in Box
Whitman Controls J205G-5S-C12L-X 3000 psig Max, 1/8" NPT Pressure Switch
Whitney Tool 96005 Series 3 9", 3/8 SH x 9/16 Exterior Diameter Drill Extension
Wika 113.13 + 990.TA, 3000 psi, 2.5" Dia, 0.25" NPT Gauge + Diaphragm Seal, !
Wild / Leitz MPS46 Photoautomat Camera Control Unit, Digital Display, No Accy's
Wild Heerbrugg M5A, 6x, 12x, 25x, 50x Microscope + (2) UWF15x Eyepieces + Stand
Wild Heerbrugg MPS 52 Microscope Camera Attachment/Adapter
Wild M4A, 1.2 to 80X Stereo Microscope, Built-in Mag Changers + 2 20X Eyepieces
Wild MPS 51 S Camera System. Consists of Wild Focusing Magnifier & Leitz Camera
Wild MPS 51 S Camera System. Consists of Wild Focusing Magnifier & Leitz Camera
Wilkerson Instrument Co. MM4001, RTD Input to DC Transmitter Mighty Module,
